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Hyperimmune IV Immunoglobulin Treatment
CHEST
Original Research CRITICAL CARE
Hyperimmune IV Immunoglobulin Treatment A Multicenter Double-Blind Randomized Controlled Trial for Patients With Severe 2009 Influenza A(H1N1) Infection Ivan F. N. Hung, MD; Kelvin K. W. To, MD; Cheuk-Kwong Lee, MD; Kar-Lung Lee, MD; Wing-Wa Yan, MD; Kenny Chan, MD; Wai-Ming Chan, MD; Chun-Wai Ngai, MD; Kin-Ip Law, MD; Fu-Loi Chow, MD; Raymond Liu, MD; Kang-Yiu Lai, MD; Candy C. Y. Lau, PhD; Shao-Haei Liu, MD; Kwok-Hung Chan, PhD; Che-Kit Lin, MD; and Kwok-Yung Yuen, MD
Background: Experience from influenza pandemics suggested that convalescent plasma treatment given within 4 to 5 days of symptom onset might be beneficial. However, robust treatment data are lacking. Methods: This is a multicenter, prospective, double-blind, randomized controlled trial. Convalescent plasma from patients who recovered from the 2009 pandemic influenza A(H1N1) (A[H1N1]) infection was fractionated to hyperimmune IV immunoglobulin (H-IVIG) by CSL Biotherapies (now BioCSL). Patients with severe A(H1N1) infection on standard antiviral treatment requiring intensive care and ventilatory support were randomized to receive H-IVIG or normal IV immunoglobulin manufactured before 2009 as control. Clinical outcome and adverse effects were compared. Results: Between 2010 and 2011, 35 patients were randomized to receive H-IVIG (17 patients) or IV immunoglobulin (18 patients). One defaulted patient was excluded from analysis. No adverse events related to treatment were reported. Baseline demographics and viral load before treatment were similar between the two groups. Serial respiratory viral load demonstrated that H-IVIG treatment was associated with significantly lower day 5 and 7 posttreatment viral load when compared with the control (P 5 .04 and P 5 .02, respectively). The initial serum cytokine level was significantly higher in the H-IVIG group but fell to a similar level 3 days after treatment. Subgroup multivariate analysis of the 22 patients who received treatment within 5 days of symptom onset demonstrated that H-IVIG treatment was the only factor that independently reduced mortality (OR, 0.14; 95% CI, 0.02-0.92; P 5 .04). Conclusions: Treatment of severe A(H1N1) infection with H-IVIG within 5 days of symptom onset was associated with a lower viral load and reduced mortality. Trial Registry: ClinialTrials.gov; No.: NCT01617317; URL: www.clinicaltrials.gov CHEST 2013; 144(2):464–473 Abbreviations: A(H1N1) 5 2009 influenza A(H1N1); H-IVIG 5 hyperimmune IV immunoglobulin; IQR 5 interquartile range; IVIG 5 IV immunoglobulin; NAT 5 neutralizing antibody titer; RT-PCR 5 reverse transcription polymerase chain reaction
influenza A(H1N1) (A[H1N1]) was the Thefirst2009 influenza pandemic of the new millennium,
causing . 18,000 deaths worldwide.1 Children and young adults were most affected because of the antigenic and structural difference between the A(H1N1) virus and seasonal H1N1 viruses.2,3 Nevertheless, extremes of age, pregnancy, and chronic underlying medical illness remained to be the main risk factors for severe disease.4 Immunodysregulation, especially
in pregnancy and obesity, was associated with high fatalities. Low serum IgG2 level was linked to severe disease associated with cytokine dysregulation.5,6 Genetic predisposition, such as polymorphism in the CD55 gene, is important for some individuals.7 Early initiation of treatment with neuraminidase inhibitors, including oseltamivir, peramivir, and zanamivir, remained the only specific treatment of severe A(H1N1) infection.1,8 Intensive care, ventilator, and extracorporeal membrane
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Original Research
oxygenation are the supportive treatments.9,10 Metaanalysis of reports from A/1918/H1N1 pandemic,11 a case report on the treatment of severe H5N1 infection,12 and a prospective cohort study on the treatment of severe A(H1N1) infection all suggested that convalescent plasma might be an effective treatment option for these severe cases.13 Nevertheless, robust data are lacking. We therefore performed a multicenter prospective double-blind randomized controlled trial by using hyperimmune IV immunoglobulin (H-IVIG) fractionated from plasma of convalescent donors to treat patients with severe A(H1N1) infection. Materials and Methods This study was a multicenter, prospective, double-blind, randomized controlled clinical trial, which included ICUs of five hospital clusters under the Hospital Authority of Hong Kong. The study was approved by the Institutional Review Board of the University of Hong Kong and the Hospital Authority (UW09-330) and registered at ClinialTrials.gov (NCT01617317). Between the period of August and October 2009, patients who had recovered from A(H1N1) infection were invited by the Hong Kong Red Cross Blood Transfusion Service to give informed consent for the donation of their convalescent plasma.13,14 All potential donors had the diagnosis of A(H1N1) infection confirmed by positive reverse transcription-polymerase chain reactions (RT-PCRs) for the influenza A virus M and pandemic H1 genes and negative RT-PCRs for the seasonal influenza A virus H1 and H3 genes in nasopharyngeal specimens. All donors must have been fully recovered from the infection for at least 2 weeks and met the current Hong Kong Red Cross Blood Transfusion Service blood donor eligibility criteria as described,14,15 with a neutralizing antibody titer (NAT) to Manuscript received December 3, 2012; revision accepted January 30, 2013. Affiliations: From the Carol Yu Center for Infection and Division of Infectious Diseases (Drs Hung, To, Lau, K.-H. Chan, and Yuen), State Key Laboratory of Emerging Infectious Diseases, the Department of Medicine (Dr Hung), and the Department of Anaesthesia and Intensive Care Unit (Drs W.-M. Chan and Ngai), Queen Mary Hospital, The University of Hong Kong, Hong Kong, China; the Hong Kong Red Cross Blood Transfusion Service (Drs C.-K. Lee and Lin); the Department of Intensive Care Unit (Drs K.-L. Lee and Law), United Christian Hospital; the Department of Intensive Care Unit (Drs Yan and K. Chan), Pamela Youde Nethersole Eastern Hospital; the Department of Medicine and Geriatrics (Dr Chow), Intensive Care Unit, Caritas Medical Centre; the Department of Medicine (Dr R. Liu), Ruttonjee Hospital and Tang Shiu Kin Hospitals; the Department of Intensive Care Medicine (Dr Lai), Queen Elizabeth Hospital, Hong Kong; and the Department of Infection (Dr S.-H. Liu), Emergency and Contingency, Hospital Authority of Hong Kong Special Administrative Region, China. Funding/Support: This study was supported by the Research Fund for the Control of Infectious Diseases, the Providence Foundation Limited in memory of the late Lui Hac Minh, and the Hospital Authority. Correspondence to: Kwok-Yung Yuen, MD, Carol Yu Center for Infection and Division of Infectious Diseases, The University of Hong Kong, Queen Mary Hospital, Pokfulam Rd, Hong Kong SAR, China; e-mail: [email protected] © 2013 American College of Chest Physicians. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details. DOI: 10.1378/chest.12-2907
A(H1N1) ⱖ 1:40. Five hundred milliliters of convalescent plasma by apheresis or whole blood was obtained from each donor and was frozen at 240°C. As previously stated, a total of 9,101 people with A(H1N1) infection confirmed by positive nasopharyngeal RT-PCR were contacted.14 Screening appointments were made for 1,309 potential donors, but only 786 attended, of whom 684 passed the health screening for the blood and plasma donation. However, 191 potential donors were subsequently excluded because of unfavorable vein size (62 of 191), inadequate hemoglobin level (55 of 191) and platelet count (16 of 191) for plasma donation, deranged liver function with high alanine transaminase level (9 of 191), failed laboratory screening for infectious diseases (18 of 191), and insufficient NAT (62 of 191). As a result, 493 potential donors were eligible for plasma donation, but only 301 attended the apheresis plasma donation appointment and donated 500 mL of plasma. Another 379 donors with NAT ⱖ 1:40 who satisfied the laboratory screening criteria also donated one unit of whole blood each. A total of 276 L of convalescent plasma was eventually shipped to CSL Biotherapies (now BioCSL) in November 2009 for fractionation to H-IVIG. Each vial of H-IVIG has a concentration of 6% (60 g/L) normal human immunoglobulin, which contains 3 g of human IgG prepared in 50 mL solution. The level of NAT to A(H1N1) in each vial of H-IVIG was confirmed to be 1:640, and this level of NAT was maintained from January 2010 to November 2011. The control IV immunoglobulin (IVIG) was manufactured from the plasma of local Chinese donors before April 2009 by CSL Biotherapies (now BioCSL). The control IVIG was tested to have NAT to A(H1N1) ⱕ 1:20, which otherwise contains an identical concentration of human immunoglobulin as the H-IVIG. Recruited patients were randomized to receive either one dose of 0.4 g/kg of H-IVIG (treatment) or 0.4 g/kg normal IVIG (control) prepared by pharmacists from the Queen Mary Hospital. The immunoglobulin solution was administered IV over a period of 4 h. Patients were closely monitored for adverse events during and after the infusion. Patients recruited were monitored by multiple clinical parameters until discharge from the ICU or death. Randomization was performed by means of a computer-generated randomization schedule, and the pharmacists had knowledge of the randomization code. During the study, neither the patients nor the physicians were aware of the types of treatment allocated. After completion of the clinical part of the study and closure of data collection, the randomization code was broken, and the physicians were notified of the actual treatment. Patients with severe A(H1N1) infection were recruited if they fulfilled the following inclusion criteria: adult patients ⱖ 18 years old with written informed consent given by patients or next-ofkin; a laboratory confirmatory diagnosis of A(H1N1) infection by positive RT-PCR from respiratory specimens, with a clinical diagnosis of severe community-acquired pneumonia as defined by a CURB-65 (severity score for community-acquired pneumonia) score ⱖ 3; deterioration despite standard enteral or oro-inhaled antiviral treatment requiring intensive care and positive pressure ventilatory support; and admission to ICU within 7 days of symptom onset. Patients were excluded if they were aged , 18 years; had known hypersensitivity to immunoglobulin or any components of the formulation; had known IgA deficiency; were moribund, with a Charlson comorbidity score . 1; they or their next-of-kin refused to give informed consent; were admitted to ICU beyond 7 days of symptom onset; or received IV antiviral therapy. Details of the data collection and microbiologic workup are found in e-Appendix 1 as previously described.13,16 Clinical and laboratory parameters were compared by Fisher exact test for categorical variables and Mann-Whitney U test for continuous variables. Significant risk factors for death were further analyzed by binary logistic regressions to identify independent
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risk factors. Log-rank test was used to evaluate the overall survival over a period of 21 days after treatment. Mann-Whitney U test was performed to assess serial viral load and cytokine level. Linear regression was used to determine the rate of viral load reduction. SPSS 17.0 for Windows (IBM) was used for statistical computation. P value , .05 was considered to represent significant difference.
Results A total of 35 patients were recruited between January 2009 and November 2011 (Fig 1). Seventeen patients (48.6%) received the H-IVIG treatment, and 18 patients (51.4%) received the IVIG treatment. One patient in the control arm who refused serial nasopharyngeal sampling and blood taking was excluded from subsequent analysis. None of the patients in the treatment or control groups developed adverse events. The two groups were well matched in their demographic and clinical characteristics (Table 1). Nineteen patients were men, and the median age was 49 years (interquartile range [IQR], 39-56.3 years). The median interval from symptom onset to ICU admission was 3 days (IQR, 1-5 days). None of the recruited patients were pregnant. Most patients had few underlying diseases and a median APACHE (Acute Physiology and Chronic Health Evaluation) II score of 12 (IQR, 8.8-18.3). Eight patients (23.5%) were
obese, and five patients (14.7%) were smokers. A majority of 32 patients (94.1%) required mechanical ventilation. Twelve patients (35.3%) required CPAP ventilation, of whom 10 (29.4%) required both CPAP and mechanical ventilation. Twelve patients (35.3%) received extracorporeal membrane oxygenation support. The use of antiviral treatment was not different between the two groups. All 34 patients received standard doses of enteral oseltamivir (75 mg/12 h), and three patients (8.8%) received standard doses of inhaled zanamivir (10 mg/12 h). Nine of the 34 patients (26.5%) died (Table 1). Univariate analysis showed no difference in mortality or length of ICU and hospital stay between the two groups. However, subgroup multivariate analysis of the 22 patients who received H-IVIG/IVIG treatment within 5 days of symptom onset showed that only H-IVIG treatment independently reduced mortality (0% vs 40%) (OR, 0.14; 95% CI, 0.02-0.92; P 5 .04) (Tables 2, 3). The log-rank test also showed that H-IVIG treatment within 5 days of symptom onset was associated with significantly better survival than IVIG treatment over a period of 21 days after treatment (P 5 .02) (Fig 2). Viral load on day 5 (3.3 vs 4.67 log10 copies/mL; P 5 .04) (Figs 3-5, Table 4) and day 7 (undetectable
Figure 1. Recruitment flowchart of the 35 patients. H-IVIG 5 hyperimmune IV immunoglobulin; IVIG 5 IV immunoglobulin. 466
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Table 1—Comparison of Demographic, Clinical, and Laboratory Factors Between the Treatment (H-IVIG) Group and the Control (IVIG) Group H-IVIG Treatment Factors Male sex Age, median (IQR), y Days of admission from symptom onset, median (IQR) Smoker Alcohol Obesity (BMI . 27) APACHE II score upon ICU admission, median (IQR) Underlying diseases Hypertension Coronary artery disease COPD Asthma Bronchiectasis Diabetes mellitus Hemoglobinopathy Schizophrenia Rheumatologic disease Presenting symptoms Fever Cough Sputum Hemoptysis Rhinorrhea Sore throat Headache Pleuritic chest pain Myalgia Dyspnea Vomiting Diarrhea Complications Ventilator-associated pneumonia Myocarditis ARDS Acute coronary syndrome Acute renal failure Treatment Mechanical ventilation CPAP ventilation ECMO Antiviral treatment Oseltamivir Inhaled zanamivir Laboratory parameters upon ICU admission, median (IQR) Hemoglobin, 109/L Neutrophil, 109/L Lymphocyte, 109/L Platelet, 109/L Bilirubin, U/L ALT, U/L Creatinine, mmol/L Sodium, mmol/L Potassium, mmol/L Outcome Mortality Length of ICU stay, d Length of hospital stay, d
Yes (n 5 17) 12 (70.6) 43 (36.5-56) 2 (1-4) 3 (17.6) 1 (5.9) 5 (29.4) 12 (8-17.5)
No (n 5 17)
P Value
7 (41.2) 52 (40.5-58.5) 3 (2-5) 2 (11.8) 1 (5.9) 3 (17.6) 13 (9-19)
NS NS NS NS NS NS NS
4 (23.5) 1 (5.9) 1 (5.9) 0 (0) 1 (5.9) 3 (17.6) 1 (5.9) 1 (5.9) 1 (5.9)
6 (35.3) 0 (0) 0 (0) 1 (5.9) 1 (5.9) 5 (29.4) 0 (0) 2 (11.8) 2 (11.8)
NS NS NS NS NS NS NS NS NS
11 (64.7) 16 (94.1) 15 (88.2) 3 (17.6) 3 (17.6) 3 (17.6) 0 (0) 1 (5.9) 1 (5.9) 14 (82.4) 1 (5.9) 0 (0)
15 (88.2) 15 (88.2) 14 (82.4) 3 (17.6) 3 (17.6) 3 (17.6) 1 (5.9) 2 (11.8) 1 (5.9) 15 (88.2) 2 (11.8) 3 (17.6)
NS NS NS NS NS NS NS NS NS NS NS NS
4 (23.5) 2 (11.8) 9 (52.9) 1 (5.9) 5 (29.4)
3 (17.6) 2 (11.8) 7 (41.2) 1 (5.9) 5 (29.4)
NS NS NS NS NS
16 (94.1) 8 (47.1) 7 (41.2)
16 (94.1) 4 (23.5) 5 (29.4)
NS NS NS
17 (100) 1 (5.9)
17 (100) 2 (11.8)
NS NS
13.2 (11-14.5) 4 (2.3-11.1) 0.7 (0.4-1.1) 171 (123.5-257) 10.8 (4.5-12.15) 54 (38.5-70.5) 76 (61.5-102.5) 137 (135.5-138.5) 3.9 (3.7-4.2)
13 (10.3-14.5) 4.3 (2.6-11.6) 0.6 (0.4-2) 166 (98.5-220) 8 (6.5-9.5) 45 (29.5-57.5) 90 (81-133.5) 135 (129.5-139) 3.9 (3.1-4.2)
NS NS NS NS NS NS NS NS NS
5 (29.4) 11 (4-13.5) 16 (11.5-13.5)
4 (23.5) 10 (4.5-13.5) 16 (7-29)
NS NS NS
Data are presented as No. (%) unless otherwise noted. ALT 5 alanine transaminase; APACHE 5 Acute Physiology and Chronic Health Evaluation; ECMO 5 extracorporeal membrane oxygenation; H-IVIG 5 hyperimmune IV immunoglobulin; IQR 5 interquartile range; IVIG 5 IV immunoglobulin, NS 5 not significant. journal.publications.chestnet.org
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Table 2—Subgroup Univariate Analysis of the 22 Patients Who Received H-IVIG/IVIG Treatment Within 5 d of Symptom Onset Patient Outcomes Factors
Survived (n 5 18)
Male sex Age, median (IQR), y Days of admission from symptoms onset, median (IQR) Smoker Alcohol Obesity (BMI . 27) APACHE II score upon ICU admission, median (IQR) Underlying diseases Hypertension Coronary artery disease Bronchiectasis Diabetes mellitus Hemoglobinopathy Schizophrenia Rheumatologic disease Presenting symptoms Fever Cough Sputum Hemoptysis Rhinorrhea Sore throat Pleuritic chest pain Myalgia Dyspnea Vomiting Diarrhea Complications Ventilator-associated pneumonia Myocarditis ARDS Acute coronary syndrome Acute renal failure Treatment Mechanical ventilation CPAP ventilation ECMO Antiviral treatment Oseltamivir Inhaled zanamivir H-IVIG Laboratory parameters upon ICU admission, median (IQR) Hemoglobin, 109/L Neutrophil, 109/L Lymphocyte, 109/L Platelet, 109/L Bilirubin, U/L ALT, U/L Creatinine, mmol/L Sodium, mmol/L Potassium, mmol/L
10 (55.6) 44 (38-56) 2 (1-3) 1 (5.6) 1 (5.6) 5 (27.8) 10.5 (8-18.3)
Died (n 5 4) 1 (25) 66.5 (45-73.8) 3 (2-5) 1 (25) 0 (0) 0 (0) 12.5 (9.3-24)
P Value NS NS NS NS NS NS NS
5 (27.8) 1 (5.6) 0 (0) 5 (27.8) 1 (5.6) 1 (5.6) 2 (11.1)
2 (50) 0 (0) 1 (25) 1 (25) 0 (0) 0 (0) 1 (25)
NS NS NS NS NS NS NS
14 (77.8) 16 (88.9) 14 (77.8) 3 (16.7) 3 (16.7) 3 (16.7) 1 (5.6) 1 (5.6) 14 (77.8) 1 (5.6) 1 (5.6)
3 (75) 4 (100) 4 (100) 1 (25) 0 (0) 0 (0) 2 (50) 0 (0) 4 (100) 0 (0) 0 (0)
NS NS NS NS NS NS NS NS NS NS NS
4 (22.2) 4 (22.2) 9 (50) 1 (5.6) 5 (27.8)
1 (25) 0 (0) 1 (25) 1 (25) 2 (50)
NS NS NS NS NS
17 (94.4) 8 (44.4) 9 (50)
4 (100) 1 (25) 0 (0)
NS NS NS
18 (100) 1 (5.6) 12 (66.7)
4 (100) 1 (25) 0 (0)
NS NS .03
12.8 (10.3-14.5) 4.6 (2.3-12.8) 0.7 (0.4-1.2) 181 (150.5-250.8) 7.5 (4.8-11.1) 53.5 (27.5-68.3) 76 (61.5-102.5) 137 (133.5-140.5) 3.9 (3.7-4.1)
12.8 (9.2-15.9) 2.4 (0.9-14.5) 0.5 (0.3-2.1) 92 (89-335) 7.7 (7-8.8) 43.5 (30.3-84.5) 78.5 (63.5-88.3) 129.5(126.8- 137.5) 4.1 (3.3-4.1)
NS NS NS NS NS NS NS NS NS
Data are presented as No. (%) unless otherwise noted. See Table 1 legend for expansion of abbreviations.
vs 4.53 log10 copies/mL; P 5 .02) (not shown) after treatment was significantly lower in the H-IVIG than the IVIG group. The viral load in the H-IVIG group was undetectable on day 6 of treatment. A greater rate of viral load reduction in the H-IVIG group (20.329
[95% CI, 20.337 to 20.322] vs 20.188 [95% CI, 20.204 to 20.177] log10 copies/mL/d) than the IVIG group was observed. The initial IL-10, IL-1 receptor antagonist, and macrophage inflammatory protein-1a levels were significantly higher in the H-IVIG group
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Table 3—Multivariate Analysis of Clinical Factors Independently Associated With Death Variable
OR
95% CI
P Value
H-IVIG treatment within 5 d of symptom onset
0.14
0.02-0.92
.04
See Table 1 legend for expansion of abbreviations.
but fell to similar levels by day 2 after treatment when compared with the IVIG group, whereas the tumor necrosis factor-a level in the H-IVIG group was significantly lower than the IVIG group by day 3 after treatment (Table 4). Subgroup analysis of the 22 patients who received H-IVIG/ IVIG treatment within 5 days of symptom onset demonstrated that mortality was associated with higher day 5 viral load (succumbed vs survived: 4.82 vs 3.53 log10 copies/mL; P 5 .062). However, there was no significant difference in the cytokine profile between the two treatment groups.
Discussion Convalescent blood products treatment during the Spanish influenza pandemic11 and the more recent A(H1N1) pandemic15 have demonstrated a significant survival benefit. Findings from this multicenter prospective double-blind randomized controlled trial provide robust evidence that treatment of severe A(H1N1) infection with H-IVIG within 5 days of symptom onset independently reduced mortality. The superior clinical outcome in the H-IVIG group correlated well with the effectively suppressed viral load and cytokine pro-
Figure 2. Kaplan-Meier estimates of 22 patients who received treatment within 5 days of symptoms onset. See Figure 1 legend for expansion of abbreviations.
Figure 3. Temporal changes of viral load and IL-6 level in treatment and control groups. See Figure 1 legend for expansion of abbreviations.
file. Despite the higher initial respiratory viral load in the H-IVIG group, the rate of viral load reduction was much more rapid when compared with the IVIG group. Serial nasopharyngeal viral load demonstrated that H-IVIG treatment was associated with significantly lower day 5 and 7 posttreatment viral load when compared with the control (P 5 .04 and P 5 .02, respectively). The initial cytokine level was also significantly higher in the H-IVIG group but fell to a level similar to the IVIG group by day 3 after treatment, suggesting that these patients may have started off with more severe disease. Previous study has reported similar findings and severity of A(H1N1) infection correlated with increased plasma level of IL-1 receptor antagonist, IL-6, and IL-10.16,17 Human models have also suggested that IL-6 induces the release of IL-10,18 which may be important in counteracting the effects of the inflammatory cytokines. Multivariate analysis of the 22 patients who received the H-IVIG/IVIG treatment within 5 days of symptom onset demonstrated that H-IVIG treatment was
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Figure 4. Temporal changes of viral load and IL-10 level in treatment and control groups. See Figure 1 legend for expansion of abbreviations.
Figure 5. Temporal changes of viral load and TNF-a level in treatment and control groups. TNF 5 tumor necrosis factor. See Figure 1 legend for expansion of other abbreviations.
the only factor that independently reduced mortality. Log-rank test also showed that H-IVIG treatment was associated with significantly better survival than IVIG treatment over a period of 21 days after treatment. These finding are comparable with those of the previous study on convalescent plasma treatment.13 Patients tolerated the H-IVIG/IVIG well. The H-IVIG has several important advantages over the convalescent plasma. First, the high level of NAT of 640 in the H-IVIG given as 0.4 g/kg provided a much more concentrated and higher level of NAT when compared with a previous case report of A/H5N1 treated by 600 mL of convalescent plasma with NAT of 80 and the case control treatment study of A(H1N1) using 500 mL of convalescent plasma with NAT ⱖ 160.12,13 Second, the convalescent plasma recipients have to match their donor’s ABO blood group and rhesus status to avoid potential transfusion reaction, whereas H-IVIG recipients do not. Third, the plasma regimen is higher in infusion volume, which may have detrimental effects in the critically ill patients. Fourth, H-IVIG/IVIG is prepared from fractionation with additional path-
ogen reduction steps by adding the methylene blue or solvent detergent, whereas the convalescent or control plasma did not undergo the steps for concentration and pathogen reduction. The amount and antibody concentration of H-IVIG/IVIG can be easily controlled during manufacturing, which is not feasible for the convalescent plasma. Therefore, the use of 0.4 g/kg of H-IVIG with NAT of 640 would balance well between donor tolerability, volume overload, and sufficient antibody delivery in recipients. The only advantage of convalescent plasma treatment is the shorter production time of about 6 weeks from convalescence to predonation screening and apheresis, whereas the production of H-IVIG from pooled convalescent plasma took about 6 months and missed the first peak of the pandemic. The convalescent whole blood transfusion used for the treatment in the 1918 influenza pandemic consisted of plasma and formed elements including monocytes and lymphocytes, which are important in both antigen presentation and adaptive immune response to influenza.11 However, the formed elements are unlikely to function in the recipients because of allo-rejection.
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Table 4—Comparison of Viral Load and Cytokine Level Between Treatment (H-IVIG) and Control (IVIG) Groups After ICU Admission in All 34 Patients Median Viral load Treatment Control P value IFN-a2 Treatment Control P value IL-1a Treatment Control P value IL-6 Treatment Control P value IL-10 Treatment Control P value IL-15 Treatment Control P value IL-1ra Treatment Control P value MCP-1 Treatment Control P value MIP-1a Treatment Control P value GM-CSF Treatment Control P value TNF-a Treatment Control P value
Day 0
Day 1
Day 2
Day 3
Day 5
5.83 5.34 .45
5.45 5.27 .14
4.46 4.66 .51
4.00 4.58 .06
3.30 4.67 .04
1.53 1.50 .19
1.44 1.30 .09
1.21 1.15 .25
1.28 1.10 .03
0.16 0.16 1.00
1.92 1.79 .61
1.92 1.59 .16
1.58 1.53 .70
1.34 1.43 .57
0.96 1.18 .30
2.15 1.75 .36
1.65 1.65 .52
1.24 1.34 .87
1.00 1.36 .35
0.65 0.98 .22
1.75 1.46 .11
1.63 1.13 .04
1.22 0.97 .06
1.07 1.09 .57
0.79 0.90 .52
1.20 1.15 .26
1.15 1.04 .36
1.11 0.87 .23
1.09 0.82 .07
0.87 0.78 .33
2.07 1.63 .26
1.68 1.36 .04
1.48 1.27 .60
1.29 1.14 .37
0.59 0.79 .83
3.51 3.11 .21
3.49 2.98 .09
2.98 2.94 .67
2.77 2.87 .16
2.67 2.69 .87
1.03 1.02 .31
0.48 0.85 .03
0.48 0.84 .98
0.63 0.88 .78
0.79 0.62 .33
1.70 1.53 .41
1.61 1.33 .07
1.35 1.25 .35
1.23 1.24 .62
1.02 1.07 .72
1.36 1.36 .84
1.22 1.34 .71
1.12 1.33 .048
1.12 1.29 .049
1.15 1.34 .14
Treatment group (H-IVIG): 17 patients; Control group (IVIG): 17 patients. Viral load: log10 copies/mL (lowest detection limit, 900 copies/mL); cytokine/chemokine concentration: log10 pg/mL. GM-CSF 5 granulocyte macrophage colony-stimulating factor, IFN-a2 5 interferon-a2, IL-1ra 5 interleukin 1 receptor antagonist; MCP-1 5 monocyte chemotactic protein-1; MIP-1a 5 macrophage inflammatory protein 1a; TNF-a 5 tumor necrosis factor-a. See Table 1 legend for expansion of other abbreviations.
Therefore, studies have turned to the use of convalescent plasma in human or specific monoclonal antibody in mice models. Convalescent plasma contains factors of the complement cascade, antimicrobial peptides and antibodies. Complement-dependent lytic antibodies can be induced by influenza virus19 and
its vaccine, which may help to control the infection or induce unwanted host cell damage. Plasma also contains important complement regulatory proteins such as CD55, which decreases host cell damage by inhibiting C3 and C5 activation and accelerating their decay.7 Moreover, it contains nonspecific inhibitor of influenza hemagglutinating activity, such as mannose-binding lectin and a-globulins. In addition, the most important component with possible effects on the outcome of severe influenza is the g-globulin fraction, which contains high-avidity neutralizing antibody against the hemagglutinin of the virus,20 nonneutralizing antibodies against other viral components, and IgG2 with opsonizing activity for encapsulated bacteria associated with secondary bacterial pneumonia. H-IVIG may augment antibody-dependent cell-mediated cytotoxicity to suppress viral load and dampen the cytokine/chemokine overactive response. Because the exact components and specificity of the g-globulin fraction of patients recovering from influenza may be different from that of vaccination, convalescent H-IVIG was used instead of postvaccination H-IVIG. The choice was also dictated by the unavailability of vaccine during the period of harvesting plasma in this study. Neuraminidase inhibitors active against the A(H1N1) are the antivirals given to the patients in this study.8 Although enteral oseltamivir and oro-inhaled zanamivir can shorten symptoms by 1 to 2 days in a normal host with nonpneumonic influenza if initiated within 48 h of symptom onset,21 it has never been shown to reduce viral load and mortality in patients with severe influenza pneumonia with respiratory failure. The efficacy of these antiviral agents in these patients with severe late-presenting disease with immunodysregulation is limited. In one of the prospective cohort studies, it was clearly shown that severe cases had delayed clearance of viral load despite treatment by enteral oseltamivir in 34 cases.16 Oseltamivir resistance can quickly develop even in treatment-naive immunosuppressed hosts with high viral load, due to the poor host immune response.22 Thus, passive immunotherapy of H-IVIG or convalescent plasma may be the other feasible treatment option. The main advantage of H-IVIG over normal IVIG is the presence of a high titer of neutralizing antibody, which can neutralize the cell-free virus and inhibit the cell-to-cell spread and cell-associated transmission. In addition, H-IVIG or IVIG could inhibit neutrophil adhesion to endothelium stimulated with IL-1a, thereby preventing endothelial activation.23 The antiinflammatory properties of immunoglobulins may in part be related to blocking IL-1a-dependent leukocyte recruitment and reduction of cytokine mRNA levels. All these mechanisms could have contributed to the prevention of ARDS developing in our patients and explain the more rapid reduction of viral load in the H-IVIG group than the IVIG group.
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Although severe A(H1N1) infection with viremia or extrapulmonary spread was more often reported in patients infected by virus with D222G mutation,24 the majority of such severe disease occurs at the extremes of age and in immunosuppressed, obese, pregnant, and poor premorbid patients.4 Immunodysregulation appears to be the predominant feature shared among these patients. In a mouse model, pregnancy was associated with severe pulmonary damage and cytokine dysregulation.25 Additionally, an IgG2 subclass deficiency has been linked to severe pandemic influenza, especially in pregnant women,6 and lower IgG2 levels in severe disease may be associated with cytokine dysregulation.5 Obesity has been found to be associated with immunodysregulation involving adipokines.26 Immunosuppressive therapy was reported to be an important cause of death for severe A(H1N1) infection in North America.27 Integrated network analyses in a macaque model demonstrated that the mechanism that normally suppresses immune cell signaling and inflammation is ineffective in the A(H1N1) virus infection.28 Moreover, lethal 1918 influenza virus infection in macaques was associated with early dysregulation of the antiviral response and atypical host innate immune response, a feature that may be shared among other virulent influenza viruses.29 Therefore, the presently reported treatment using H-IVIG may achieve both antiviral and immunomodulatory activity, which may be additive to or synergize with the treatment with neuraminidase inhibitors alone in patients with immaturity, dysregulation, and senescence of their immune system. Limitations of the present study included the relatively small number of patients recruited because of the early decline of the A(H1N1) pandemic and the relatively long period required in fractionation of convalescent plasma to H-IVIG. Potential candidates were often excluded because of late presentation to the ICU. Although there were more men in the treatment arm (but not a significant number), data from the Centre for Health Protection showed that more men developed severe diseases from the A(H1N1) pandemic in Hong Kong.30 Nevertheless, the prospective multicenter randomized double-blind nature of this study and the availability of serial viral load and cytokine profiles before and after treatment allowed a robust comparison with the control. This present study is a very unique and valuable opportunity offered by this pandemic, because our comparison is only valid if the control IVIG has only low background antibodies against A(H1N1). In conclusion, the beneficial effects demonstrated in this study appear to be related to the A(H1N1) antibody in the convalescent H-IVIG. This modality of treatment should be considered in future pandemics.11,31
Acknowledgments Author contributions: Drs Hung and Yuen had full access to the data and take responsibility for the manuscript. Dr Hung: contributed to study design, data collection, data analysis, data interpretation, and writing and revision of the manuscript. Dr To: contributed to data analysis, data interpretation, and writing and revision of the manuscript. Dr C.-K. Lee: contributed to study design, data collection, data interpretation, and writing and revision of the manuscript. Dr K.-L. Lee: contributed to data collection and writing of the manuscript. Dr Yan: contributed to study design, data collection, and writing of the manuscript. Dr K. Chan: contributed to data collection and writing of the manuscript. Dr W.-M. Chan: contributed to data collection and writing of the manuscript. Dr Ngai: contributed to data collection and writing of the manuscript. Dr Law: contributed to data collection and writing of the manuscript. Dr Chow: contributed to data collection and writing of the manuscript. Dr R. Liu: contributed to data collection and writing of the manuscript. Dr Lai: contributed to data collection and writing of the manuscript. Dr Lau: contributed to data analysis and writing of the manuscript. Dr S.-H. Liu: contributed to study design and writing of the manuscript. Dr K.-H. Chan: contributed to data collection, data analysis, and writing and revision of the manuscript. Dr Lin: contributed to study design, data collection, and writing of the manuscript. Dr Yuen: contributed to study design, data analysis, data interpretation, and writing and revision of the manuscript. Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article. Role of sponsors: The sponsor had no role in the design of the study, the collection and analysis of the data, or the preparation of the manuscript. Other contributions: We thank the Research Fund for the Control of Infectious Diseases, the Providence Foundation Limited in memory of the late Lui Hac Minh, and the Hospital Authority for supporting this study. We also thank the convalescent plasma donors and colleagues from the Hospital Authority, the Hong Kong Red Cross and Blood Transfusion Service, and the University of Hong Kong who participated in this study. We thank Patrick Li, BSc; Clara Li, BSc; Whitney Ip, BSc; Peggy Chan, BSc; Linda Cheung, BSc; Kiki Yeung, BSc; Cecilia Koo, BSc; and William Chui, BSc, for their important assistance in this study. Additional information: The e-Appendix can be found in the “Supplemental Materials” area of the online article.
References 1. Cheng VC, To KK, Tse H, Hung IF, Yuen KY. Two years after pandemic influenza A/2009/H1N1: what have we learned? Clin Microbiol Rev. 2012;25(2):223-263. 2. To KK, Wong SS, Li IW, et al. Concurrent comparison of epidemiology, clinical presentation and outcome between adult patients suffering from the pandemic influenza A (H1N1) 2009 virus and the seasonal influenza A virus infection. Postgrad Med J. 2010;86(1019):515-521. 3. Hancock K, Veguilla V, Lu X, et al. Cross-reactive antibody responses to the 2009 pandemic H1N1 influenza virus. N Engl J Med. 2009;361(20):1945-1952.
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4. Louie JK, Acosta M, Winter K, et al; California Pandemic (H1N1) Working Group. Factors associated with death or hospitalization due to pandemic 2009 influenza A(H1N1) infection in California. JAMA. 2009;302(17):1896-1902. 5. Chan JF, To KK, Tse H, et al. The lower serum immunoglobulin G2 level in severe cases than in mild cases of pandemic H1N1 2009 influenza is associated with cytokine dysregulation. Clin Vaccine Immunol. 2011;18(2):305-310. 6. Gordon CL, Johnson PD, Permezel M, et al. Association between severe pandemic 2009 influenza A (H1N1) virus infection and immunoglobulin G(2) subclass deficiency. Clin Infect Dis. 2010;50(5):672-678. 7. Zhou J, To KK, Dong H, et al. A functional variation in CD55 increases the severity of 2009 pandemic H1N1 influenza A virus infection. J Infect Dis. 2012;206(4):495-503. 8. Li IW, Hung IF, To KK, et al. The natural viral load profile of patients with pandemic 2009 influenza A(H1N1) and the effect of oseltamivir treatment. Chest. 2010;137(4): 759-768. 9. Davies A, Jones D, Bailey M, et al; Australia and New Zealand Extracorporeal Membrane Oxygenation (ANZ ECMO) Influenza Investigators. Extracorporeal membrane oxygenation for 2009 influenza A(H1N1) acute respiratory distress syndrome. JAMA. 2009;302(17):1888-1895. 10. Chan KK, Lee KL, Lam PK, Law KI, Joynt GM, Yan WW. Hong Kong’s experience on the use of extracorporeal membrane oxygenation for the treatment of influenza A (H1N1). Hong Kong Med J. 2010;16(6):447-454. 11. Luke TC, Kilbane EM, Jackson JL, Hoffman SL. Metaanalysis: convalescent blood products for Spanish influenza pneumonia: a future H5N1 treatment? Ann Intern Med. 2006; 145(8):599-609. 12. Zhou B, Zhong N, Guan Y. Treatment with convalescent plasma for influenza A (H5N1) infection. N Engl J Med. 2007; 357(14):1450-1451. 13. Hung IF, To KK, Lee CK, et al. Convalescent plasma treatment reduced mortality in patients with severe pandemic influenza A (H1N1) 2009 virus infection. Clin Infect Dis. 2011; 52(4):447-456. 14. Wong HK, Lee CK, Hung IF, et al. Practical limitations of convalescent plasma collection: a case scenario in pandemic preparation for influenza A (H1N1) infection. Transfusion. 2010;50(9):1967-1971. 15. Hung IF, To KK, Lee CK, et al. Effect of clinical and virological parameters on the level of neutralizing antibody against pandemic influenza A virus H1N1 2009. Clin Infect Dis. 2010; 51(3):274-279. 16. To KK, Hung IF, Li IW, et al. Delayed clearance of viral load and marked cytokine activation in severe cases of pandemic H1N1 2009 influenza virus infection. Clin Infect Dis. 2010; 50(6):850-859.
17. Arankalle VA, Lole KS, Arya RP, et al. Role of host immune response and viral load in the differential outcome of pandemic H1N1 (2009) influenza virus infection in Indian patients. PLoS One. 2010;5(10).pii:e13099. 18. Steensberg A, Fischer CP, Keller C, Møller K, Pedersen BK. IL-6 enhances plasma IL-1ra, IL-10, and cortisol in humans. Am J Physiol Endocrinol Metab. 2003;285(2):E433-E437. 19. Monsalvo AC, Batalle JP, Lopez MF, et al. Severe pandemic 2009 H1N1 influenza disease due to pathogenic immune complexes. Nat Med. 2011;17(2):195-199. 20. To KK, Zhang AJ, Hung IF, et al. High titer and avidity of nonneutralizing antibodies against influenza vaccine antigen are associated with severe influenza. Clin Vaccine Immunol. 2012;19(7):1012-1018. 21. Jefferson T, Demicheli V, Deeks J, Rivetti D. Neuraminidase inhibitors for preventing and treating influenza in healthy adults. Cochrane Database Syst Rev. 2000;(2):CD001265. 22. Inoue M, Barkham T, Leo YS, et al. Emergence of oseltamivirresistant pandemic (H1N1) 2009 virus within 48 hours. Emerg Infect Dis. 2010;16(10):1633-1636. 23. Macmillan HF, Rowter D, Lee T, Issekutz AC. Intravenous immunoglobulin G selectively inhibits IL-1a-induced neutrophil-endothelial cell adhesion. Autoimmunity. 2010; 43(8):619-627. 24. Tse H, To KK, Wen X, et al. Clinical and virological factors associated with viremia in pandemic influenza A/H1N1/2009 virus infection. PLoS ONE. 2011;6(9):e22534. 25. Chan KH, Zhang AJ, To KK, et al. Wild type and mutant 2009 pandemic influenza A (H1N1) viruses cause more severe disease and higher mortality in pregnant BALB/c mice. PLoS ONE. 2010;5(10):e13757. 26. Nave H, Beutel G, Kielstein JT. Obesity-related immunodeficiency in patients with pandemic influenza H1N1. Lancet Infect Dis. 2011;11(1):14-15. 27. Fowlkes AL, Arguin P, Biggerstaff MS, et al. Epidemiology of 2009 pandemic influenza A (H1N1) deaths in the United States, April-July 2009. Clin Infect Dis. 2011;52(suppl 1):S60-S68. 28. Shoemaker JE, Fukuyama S, Eisfeld AJ, et al. Integrated network analysis reveals a novel role for the cell cycle in 2009 pandemic influenza virus-induced inflammation in macaque lungs. BMC Syst Biol. 2012;6:117. 29. Kobasa D, Jones SM, Shinya K, et al. Aberrant innate immune response in lethal infection of macaques with the 1918 influenza virus. Nature. 2007;445(7125):319-323. 30. Swine and Seasonal Flu Monitor. Centre for Health Protection website. http://www.chp.gov.hk/files/pdf/revised_SSFM_7_ 10_2010.pdf. Accessed September 25, 2012. 31. Wu JT, Lee CK, Cowling BJ, Yuen KY. Logistical feasibility and potential benefits of a population-wide passive-immunotherapy program during an influenza pandemic. Proc Natl Acad Sci U S A. 2010;107(7):3269-3274.
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Original Research CRITICAL CARE
Hyperimmune IV Immunoglobulin Treatment A Multicenter Double-Blind Randomized Controlled Trial for Patients With Severe 2009 Influenza A(H1N1) Infection Ivan F. N. Hung, MD; Kelvin K. W. To, MD; Cheuk-Kwong Lee, MD; Kar-Lung Lee, MD; Wing-Wa Yan, MD; Kenny Chan, MD; Wai-Ming Chan, MD; Chun-Wai Ngai, MD; Kin-Ip Law, MD; Fu-Loi Chow, MD; Raymond Liu, MD; Kang-Yiu Lai, MD; Candy C. Y. Lau, PhD; Shao-Haei Liu, MD; Kwok-Hung Chan, PhD; Che-Kit Lin, MD; and Kwok-Yung Yuen, MD
Background: Experience from influenza pandemics suggested that convalescent plasma treatment given within 4 to 5 days of symptom onset might be beneficial. However, robust treatment data are lacking. Methods: This is a multicenter, prospective, double-blind, randomized controlled trial. Convalescent plasma from patients who recovered from the 2009 pandemic influenza A(H1N1) (A[H1N1]) infection was fractionated to hyperimmune IV immunoglobulin (H-IVIG) by CSL Biotherapies (now BioCSL). Patients with severe A(H1N1) infection on standard antiviral treatment requiring intensive care and ventilatory support were randomized to receive H-IVIG or normal IV immunoglobulin manufactured before 2009 as control. Clinical outcome and adverse effects were compared. Results: Between 2010 and 2011, 35 patients were randomized to receive H-IVIG (17 patients) or IV immunoglobulin (18 patients). One defaulted patient was excluded from analysis. No adverse events related to treatment were reported. Baseline demographics and viral load before treatment were similar between the two groups. Serial respiratory viral load demonstrated that H-IVIG treatment was associated with significantly lower day 5 and 7 posttreatment viral load when compared with the control (P 5 .04 and P 5 .02, respectively). The initial serum cytokine level was significantly higher in the H-IVIG group but fell to a similar level 3 days after treatment. Subgroup multivariate analysis of the 22 patients who received treatment within 5 days of symptom onset demonstrated that H-IVIG treatment was the only factor that independently reduced mortality (OR, 0.14; 95% CI, 0.02-0.92; P 5 .04). Conclusions: Treatment of severe A(H1N1) infection with H-IVIG within 5 days of symptom onset was associated with a lower viral load and reduced mortality. Trial Registry: ClinialTrials.gov; No.: NCT01617317; URL: www.clinicaltrials.gov CHEST 2013; 144(2):464–473 Abbreviations: A(H1N1) 5 2009 influenza A(H1N1); H-IVIG 5 hyperimmune IV immunoglobulin; IQR 5 interquartile range; IVIG 5 IV immunoglobulin; NAT 5 neutralizing antibody titer; RT-PCR 5 reverse transcription polymerase chain reaction
influenza A(H1N1) (A[H1N1]) was the Thefirst2009 influenza pandemic of the new millennium,
causing . 18,000 deaths worldwide.1 Children and young adults were most affected because of the antigenic and structural difference between the A(H1N1) virus and seasonal H1N1 viruses.2,3 Nevertheless, extremes of age, pregnancy, and chronic underlying medical illness remained to be the main risk factors for severe disease.4 Immunodysregulation, especially
in pregnancy and obesity, was associated with high fatalities. Low serum IgG2 level was linked to severe disease associated with cytokine dysregulation.5,6 Genetic predisposition, such as polymorphism in the CD55 gene, is important for some individuals.7 Early initiation of treatment with neuraminidase inhibitors, including oseltamivir, peramivir, and zanamivir, remained the only specific treatment of severe A(H1N1) infection.1,8 Intensive care, ventilator, and extracorporeal membrane
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oxygenation are the supportive treatments.9,10 Metaanalysis of reports from A/1918/H1N1 pandemic,11 a case report on the treatment of severe H5N1 infection,12 and a prospective cohort study on the treatment of severe A(H1N1) infection all suggested that convalescent plasma might be an effective treatment option for these severe cases.13 Nevertheless, robust data are lacking. We therefore performed a multicenter prospective double-blind randomized controlled trial by using hyperimmune IV immunoglobulin (H-IVIG) fractionated from plasma of convalescent donors to treat patients with severe A(H1N1) infection. Materials and Methods This study was a multicenter, prospective, double-blind, randomized controlled clinical trial, which included ICUs of five hospital clusters under the Hospital Authority of Hong Kong. The study was approved by the Institutional Review Board of the University of Hong Kong and the Hospital Authority (UW09-330) and registered at ClinialTrials.gov (NCT01617317). Between the period of August and October 2009, patients who had recovered from A(H1N1) infection were invited by the Hong Kong Red Cross Blood Transfusion Service to give informed consent for the donation of their convalescent plasma.13,14 All potential donors had the diagnosis of A(H1N1) infection confirmed by positive reverse transcription-polymerase chain reactions (RT-PCRs) for the influenza A virus M and pandemic H1 genes and negative RT-PCRs for the seasonal influenza A virus H1 and H3 genes in nasopharyngeal specimens. All donors must have been fully recovered from the infection for at least 2 weeks and met the current Hong Kong Red Cross Blood Transfusion Service blood donor eligibility criteria as described,14,15 with a neutralizing antibody titer (NAT) to Manuscript received December 3, 2012; revision accepted January 30, 2013. Affiliations: From the Carol Yu Center for Infection and Division of Infectious Diseases (Drs Hung, To, Lau, K.-H. Chan, and Yuen), State Key Laboratory of Emerging Infectious Diseases, the Department of Medicine (Dr Hung), and the Department of Anaesthesia and Intensive Care Unit (Drs W.-M. Chan and Ngai), Queen Mary Hospital, The University of Hong Kong, Hong Kong, China; the Hong Kong Red Cross Blood Transfusion Service (Drs C.-K. Lee and Lin); the Department of Intensive Care Unit (Drs K.-L. Lee and Law), United Christian Hospital; the Department of Intensive Care Unit (Drs Yan and K. Chan), Pamela Youde Nethersole Eastern Hospital; the Department of Medicine and Geriatrics (Dr Chow), Intensive Care Unit, Caritas Medical Centre; the Department of Medicine (Dr R. Liu), Ruttonjee Hospital and Tang Shiu Kin Hospitals; the Department of Intensive Care Medicine (Dr Lai), Queen Elizabeth Hospital, Hong Kong; and the Department of Infection (Dr S.-H. Liu), Emergency and Contingency, Hospital Authority of Hong Kong Special Administrative Region, China. Funding/Support: This study was supported by the Research Fund for the Control of Infectious Diseases, the Providence Foundation Limited in memory of the late Lui Hac Minh, and the Hospital Authority. Correspondence to: Kwok-Yung Yuen, MD, Carol Yu Center for Infection and Division of Infectious Diseases, The University of Hong Kong, Queen Mary Hospital, Pokfulam Rd, Hong Kong SAR, China; e-mail: [email protected] © 2013 American College of Chest Physicians. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details. DOI: 10.1378/chest.12-2907
A(H1N1) ⱖ 1:40. Five hundred milliliters of convalescent plasma by apheresis or whole blood was obtained from each donor and was frozen at 240°C. As previously stated, a total of 9,101 people with A(H1N1) infection confirmed by positive nasopharyngeal RT-PCR were contacted.14 Screening appointments were made for 1,309 potential donors, but only 786 attended, of whom 684 passed the health screening for the blood and plasma donation. However, 191 potential donors were subsequently excluded because of unfavorable vein size (62 of 191), inadequate hemoglobin level (55 of 191) and platelet count (16 of 191) for plasma donation, deranged liver function with high alanine transaminase level (9 of 191), failed laboratory screening for infectious diseases (18 of 191), and insufficient NAT (62 of 191). As a result, 493 potential donors were eligible for plasma donation, but only 301 attended the apheresis plasma donation appointment and donated 500 mL of plasma. Another 379 donors with NAT ⱖ 1:40 who satisfied the laboratory screening criteria also donated one unit of whole blood each. A total of 276 L of convalescent plasma was eventually shipped to CSL Biotherapies (now BioCSL) in November 2009 for fractionation to H-IVIG. Each vial of H-IVIG has a concentration of 6% (60 g/L) normal human immunoglobulin, which contains 3 g of human IgG prepared in 50 mL solution. The level of NAT to A(H1N1) in each vial of H-IVIG was confirmed to be 1:640, and this level of NAT was maintained from January 2010 to November 2011. The control IV immunoglobulin (IVIG) was manufactured from the plasma of local Chinese donors before April 2009 by CSL Biotherapies (now BioCSL). The control IVIG was tested to have NAT to A(H1N1) ⱕ 1:20, which otherwise contains an identical concentration of human immunoglobulin as the H-IVIG. Recruited patients were randomized to receive either one dose of 0.4 g/kg of H-IVIG (treatment) or 0.4 g/kg normal IVIG (control) prepared by pharmacists from the Queen Mary Hospital. The immunoglobulin solution was administered IV over a period of 4 h. Patients were closely monitored for adverse events during and after the infusion. Patients recruited were monitored by multiple clinical parameters until discharge from the ICU or death. Randomization was performed by means of a computer-generated randomization schedule, and the pharmacists had knowledge of the randomization code. During the study, neither the patients nor the physicians were aware of the types of treatment allocated. After completion of the clinical part of the study and closure of data collection, the randomization code was broken, and the physicians were notified of the actual treatment. Patients with severe A(H1N1) infection were recruited if they fulfilled the following inclusion criteria: adult patients ⱖ 18 years old with written informed consent given by patients or next-ofkin; a laboratory confirmatory diagnosis of A(H1N1) infection by positive RT-PCR from respiratory specimens, with a clinical diagnosis of severe community-acquired pneumonia as defined by a CURB-65 (severity score for community-acquired pneumonia) score ⱖ 3; deterioration despite standard enteral or oro-inhaled antiviral treatment requiring intensive care and positive pressure ventilatory support; and admission to ICU within 7 days of symptom onset. Patients were excluded if they were aged , 18 years; had known hypersensitivity to immunoglobulin or any components of the formulation; had known IgA deficiency; were moribund, with a Charlson comorbidity score . 1; they or their next-of-kin refused to give informed consent; were admitted to ICU beyond 7 days of symptom onset; or received IV antiviral therapy. Details of the data collection and microbiologic workup are found in e-Appendix 1 as previously described.13,16 Clinical and laboratory parameters were compared by Fisher exact test for categorical variables and Mann-Whitney U test for continuous variables. Significant risk factors for death were further analyzed by binary logistic regressions to identify independent
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risk factors. Log-rank test was used to evaluate the overall survival over a period of 21 days after treatment. Mann-Whitney U test was performed to assess serial viral load and cytokine level. Linear regression was used to determine the rate of viral load reduction. SPSS 17.0 for Windows (IBM) was used for statistical computation. P value , .05 was considered to represent significant difference.
Results A total of 35 patients were recruited between January 2009 and November 2011 (Fig 1). Seventeen patients (48.6%) received the H-IVIG treatment, and 18 patients (51.4%) received the IVIG treatment. One patient in the control arm who refused serial nasopharyngeal sampling and blood taking was excluded from subsequent analysis. None of the patients in the treatment or control groups developed adverse events. The two groups were well matched in their demographic and clinical characteristics (Table 1). Nineteen patients were men, and the median age was 49 years (interquartile range [IQR], 39-56.3 years). The median interval from symptom onset to ICU admission was 3 days (IQR, 1-5 days). None of the recruited patients were pregnant. Most patients had few underlying diseases and a median APACHE (Acute Physiology and Chronic Health Evaluation) II score of 12 (IQR, 8.8-18.3). Eight patients (23.5%) were
obese, and five patients (14.7%) were smokers. A majority of 32 patients (94.1%) required mechanical ventilation. Twelve patients (35.3%) required CPAP ventilation, of whom 10 (29.4%) required both CPAP and mechanical ventilation. Twelve patients (35.3%) received extracorporeal membrane oxygenation support. The use of antiviral treatment was not different between the two groups. All 34 patients received standard doses of enteral oseltamivir (75 mg/12 h), and three patients (8.8%) received standard doses of inhaled zanamivir (10 mg/12 h). Nine of the 34 patients (26.5%) died (Table 1). Univariate analysis showed no difference in mortality or length of ICU and hospital stay between the two groups. However, subgroup multivariate analysis of the 22 patients who received H-IVIG/IVIG treatment within 5 days of symptom onset showed that only H-IVIG treatment independently reduced mortality (0% vs 40%) (OR, 0.14; 95% CI, 0.02-0.92; P 5 .04) (Tables 2, 3). The log-rank test also showed that H-IVIG treatment within 5 days of symptom onset was associated with significantly better survival than IVIG treatment over a period of 21 days after treatment (P 5 .02) (Fig 2). Viral load on day 5 (3.3 vs 4.67 log10 copies/mL; P 5 .04) (Figs 3-5, Table 4) and day 7 (undetectable
Figure 1. Recruitment flowchart of the 35 patients. H-IVIG 5 hyperimmune IV immunoglobulin; IVIG 5 IV immunoglobulin. 466
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Table 1—Comparison of Demographic, Clinical, and Laboratory Factors Between the Treatment (H-IVIG) Group and the Control (IVIG) Group H-IVIG Treatment Factors Male sex Age, median (IQR), y Days of admission from symptom onset, median (IQR) Smoker Alcohol Obesity (BMI . 27) APACHE II score upon ICU admission, median (IQR) Underlying diseases Hypertension Coronary artery disease COPD Asthma Bronchiectasis Diabetes mellitus Hemoglobinopathy Schizophrenia Rheumatologic disease Presenting symptoms Fever Cough Sputum Hemoptysis Rhinorrhea Sore throat Headache Pleuritic chest pain Myalgia Dyspnea Vomiting Diarrhea Complications Ventilator-associated pneumonia Myocarditis ARDS Acute coronary syndrome Acute renal failure Treatment Mechanical ventilation CPAP ventilation ECMO Antiviral treatment Oseltamivir Inhaled zanamivir Laboratory parameters upon ICU admission, median (IQR) Hemoglobin, 109/L Neutrophil, 109/L Lymphocyte, 109/L Platelet, 109/L Bilirubin, U/L ALT, U/L Creatinine, mmol/L Sodium, mmol/L Potassium, mmol/L Outcome Mortality Length of ICU stay, d Length of hospital stay, d
Yes (n 5 17) 12 (70.6) 43 (36.5-56) 2 (1-4) 3 (17.6) 1 (5.9) 5 (29.4) 12 (8-17.5)
No (n 5 17)
P Value
7 (41.2) 52 (40.5-58.5) 3 (2-5) 2 (11.8) 1 (5.9) 3 (17.6) 13 (9-19)
NS NS NS NS NS NS NS
4 (23.5) 1 (5.9) 1 (5.9) 0 (0) 1 (5.9) 3 (17.6) 1 (5.9) 1 (5.9) 1 (5.9)
6 (35.3) 0 (0) 0 (0) 1 (5.9) 1 (5.9) 5 (29.4) 0 (0) 2 (11.8) 2 (11.8)
NS NS NS NS NS NS NS NS NS
11 (64.7) 16 (94.1) 15 (88.2) 3 (17.6) 3 (17.6) 3 (17.6) 0 (0) 1 (5.9) 1 (5.9) 14 (82.4) 1 (5.9) 0 (0)
15 (88.2) 15 (88.2) 14 (82.4) 3 (17.6) 3 (17.6) 3 (17.6) 1 (5.9) 2 (11.8) 1 (5.9) 15 (88.2) 2 (11.8) 3 (17.6)
NS NS NS NS NS NS NS NS NS NS NS NS
4 (23.5) 2 (11.8) 9 (52.9) 1 (5.9) 5 (29.4)
3 (17.6) 2 (11.8) 7 (41.2) 1 (5.9) 5 (29.4)
NS NS NS NS NS
16 (94.1) 8 (47.1) 7 (41.2)
16 (94.1) 4 (23.5) 5 (29.4)
NS NS NS
17 (100) 1 (5.9)
17 (100) 2 (11.8)
NS NS
13.2 (11-14.5) 4 (2.3-11.1) 0.7 (0.4-1.1) 171 (123.5-257) 10.8 (4.5-12.15) 54 (38.5-70.5) 76 (61.5-102.5) 137 (135.5-138.5) 3.9 (3.7-4.2)
13 (10.3-14.5) 4.3 (2.6-11.6) 0.6 (0.4-2) 166 (98.5-220) 8 (6.5-9.5) 45 (29.5-57.5) 90 (81-133.5) 135 (129.5-139) 3.9 (3.1-4.2)
NS NS NS NS NS NS NS NS NS
5 (29.4) 11 (4-13.5) 16 (11.5-13.5)
4 (23.5) 10 (4.5-13.5) 16 (7-29)
NS NS NS
Data are presented as No. (%) unless otherwise noted. ALT 5 alanine transaminase; APACHE 5 Acute Physiology and Chronic Health Evaluation; ECMO 5 extracorporeal membrane oxygenation; H-IVIG 5 hyperimmune IV immunoglobulin; IQR 5 interquartile range; IVIG 5 IV immunoglobulin, NS 5 not significant. journal.publications.chestnet.org
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Table 2—Subgroup Univariate Analysis of the 22 Patients Who Received H-IVIG/IVIG Treatment Within 5 d of Symptom Onset Patient Outcomes Factors
Survived (n 5 18)
Male sex Age, median (IQR), y Days of admission from symptoms onset, median (IQR) Smoker Alcohol Obesity (BMI . 27) APACHE II score upon ICU admission, median (IQR) Underlying diseases Hypertension Coronary artery disease Bronchiectasis Diabetes mellitus Hemoglobinopathy Schizophrenia Rheumatologic disease Presenting symptoms Fever Cough Sputum Hemoptysis Rhinorrhea Sore throat Pleuritic chest pain Myalgia Dyspnea Vomiting Diarrhea Complications Ventilator-associated pneumonia Myocarditis ARDS Acute coronary syndrome Acute renal failure Treatment Mechanical ventilation CPAP ventilation ECMO Antiviral treatment Oseltamivir Inhaled zanamivir H-IVIG Laboratory parameters upon ICU admission, median (IQR) Hemoglobin, 109/L Neutrophil, 109/L Lymphocyte, 109/L Platelet, 109/L Bilirubin, U/L ALT, U/L Creatinine, mmol/L Sodium, mmol/L Potassium, mmol/L
10 (55.6) 44 (38-56) 2 (1-3) 1 (5.6) 1 (5.6) 5 (27.8) 10.5 (8-18.3)
Died (n 5 4) 1 (25) 66.5 (45-73.8) 3 (2-5) 1 (25) 0 (0) 0 (0) 12.5 (9.3-24)
P Value NS NS NS NS NS NS NS
5 (27.8) 1 (5.6) 0 (0) 5 (27.8) 1 (5.6) 1 (5.6) 2 (11.1)
2 (50) 0 (0) 1 (25) 1 (25) 0 (0) 0 (0) 1 (25)
NS NS NS NS NS NS NS
14 (77.8) 16 (88.9) 14 (77.8) 3 (16.7) 3 (16.7) 3 (16.7) 1 (5.6) 1 (5.6) 14 (77.8) 1 (5.6) 1 (5.6)
3 (75) 4 (100) 4 (100) 1 (25) 0 (0) 0 (0) 2 (50) 0 (0) 4 (100) 0 (0) 0 (0)
NS NS NS NS NS NS NS NS NS NS NS
4 (22.2) 4 (22.2) 9 (50) 1 (5.6) 5 (27.8)
1 (25) 0 (0) 1 (25) 1 (25) 2 (50)
NS NS NS NS NS
17 (94.4) 8 (44.4) 9 (50)
4 (100) 1 (25) 0 (0)
NS NS NS
18 (100) 1 (5.6) 12 (66.7)
4 (100) 1 (25) 0 (0)
NS NS .03
12.8 (10.3-14.5) 4.6 (2.3-12.8) 0.7 (0.4-1.2) 181 (150.5-250.8) 7.5 (4.8-11.1) 53.5 (27.5-68.3) 76 (61.5-102.5) 137 (133.5-140.5) 3.9 (3.7-4.1)
12.8 (9.2-15.9) 2.4 (0.9-14.5) 0.5 (0.3-2.1) 92 (89-335) 7.7 (7-8.8) 43.5 (30.3-84.5) 78.5 (63.5-88.3) 129.5(126.8- 137.5) 4.1 (3.3-4.1)
NS NS NS NS NS NS NS NS NS
Data are presented as No. (%) unless otherwise noted. See Table 1 legend for expansion of abbreviations.
vs 4.53 log10 copies/mL; P 5 .02) (not shown) after treatment was significantly lower in the H-IVIG than the IVIG group. The viral load in the H-IVIG group was undetectable on day 6 of treatment. A greater rate of viral load reduction in the H-IVIG group (20.329
[95% CI, 20.337 to 20.322] vs 20.188 [95% CI, 20.204 to 20.177] log10 copies/mL/d) than the IVIG group was observed. The initial IL-10, IL-1 receptor antagonist, and macrophage inflammatory protein-1a levels were significantly higher in the H-IVIG group
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Table 3—Multivariate Analysis of Clinical Factors Independently Associated With Death Variable
OR
95% CI
P Value
H-IVIG treatment within 5 d of symptom onset
0.14
0.02-0.92
.04
See Table 1 legend for expansion of abbreviations.
but fell to similar levels by day 2 after treatment when compared with the IVIG group, whereas the tumor necrosis factor-a level in the H-IVIG group was significantly lower than the IVIG group by day 3 after treatment (Table 4). Subgroup analysis of the 22 patients who received H-IVIG/ IVIG treatment within 5 days of symptom onset demonstrated that mortality was associated with higher day 5 viral load (succumbed vs survived: 4.82 vs 3.53 log10 copies/mL; P 5 .062). However, there was no significant difference in the cytokine profile between the two treatment groups.
Discussion Convalescent blood products treatment during the Spanish influenza pandemic11 and the more recent A(H1N1) pandemic15 have demonstrated a significant survival benefit. Findings from this multicenter prospective double-blind randomized controlled trial provide robust evidence that treatment of severe A(H1N1) infection with H-IVIG within 5 days of symptom onset independently reduced mortality. The superior clinical outcome in the H-IVIG group correlated well with the effectively suppressed viral load and cytokine pro-
Figure 2. Kaplan-Meier estimates of 22 patients who received treatment within 5 days of symptoms onset. See Figure 1 legend for expansion of abbreviations.
Figure 3. Temporal changes of viral load and IL-6 level in treatment and control groups. See Figure 1 legend for expansion of abbreviations.
file. Despite the higher initial respiratory viral load in the H-IVIG group, the rate of viral load reduction was much more rapid when compared with the IVIG group. Serial nasopharyngeal viral load demonstrated that H-IVIG treatment was associated with significantly lower day 5 and 7 posttreatment viral load when compared with the control (P 5 .04 and P 5 .02, respectively). The initial cytokine level was also significantly higher in the H-IVIG group but fell to a level similar to the IVIG group by day 3 after treatment, suggesting that these patients may have started off with more severe disease. Previous study has reported similar findings and severity of A(H1N1) infection correlated with increased plasma level of IL-1 receptor antagonist, IL-6, and IL-10.16,17 Human models have also suggested that IL-6 induces the release of IL-10,18 which may be important in counteracting the effects of the inflammatory cytokines. Multivariate analysis of the 22 patients who received the H-IVIG/IVIG treatment within 5 days of symptom onset demonstrated that H-IVIG treatment was
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Figure 4. Temporal changes of viral load and IL-10 level in treatment and control groups. See Figure 1 legend for expansion of abbreviations.
Figure 5. Temporal changes of viral load and TNF-a level in treatment and control groups. TNF 5 tumor necrosis factor. See Figure 1 legend for expansion of other abbreviations.
the only factor that independently reduced mortality. Log-rank test also showed that H-IVIG treatment was associated with significantly better survival than IVIG treatment over a period of 21 days after treatment. These finding are comparable with those of the previous study on convalescent plasma treatment.13 Patients tolerated the H-IVIG/IVIG well. The H-IVIG has several important advantages over the convalescent plasma. First, the high level of NAT of 640 in the H-IVIG given as 0.4 g/kg provided a much more concentrated and higher level of NAT when compared with a previous case report of A/H5N1 treated by 600 mL of convalescent plasma with NAT of 80 and the case control treatment study of A(H1N1) using 500 mL of convalescent plasma with NAT ⱖ 160.12,13 Second, the convalescent plasma recipients have to match their donor’s ABO blood group and rhesus status to avoid potential transfusion reaction, whereas H-IVIG recipients do not. Third, the plasma regimen is higher in infusion volume, which may have detrimental effects in the critically ill patients. Fourth, H-IVIG/IVIG is prepared from fractionation with additional path-
ogen reduction steps by adding the methylene blue or solvent detergent, whereas the convalescent or control plasma did not undergo the steps for concentration and pathogen reduction. The amount and antibody concentration of H-IVIG/IVIG can be easily controlled during manufacturing, which is not feasible for the convalescent plasma. Therefore, the use of 0.4 g/kg of H-IVIG with NAT of 640 would balance well between donor tolerability, volume overload, and sufficient antibody delivery in recipients. The only advantage of convalescent plasma treatment is the shorter production time of about 6 weeks from convalescence to predonation screening and apheresis, whereas the production of H-IVIG from pooled convalescent plasma took about 6 months and missed the first peak of the pandemic. The convalescent whole blood transfusion used for the treatment in the 1918 influenza pandemic consisted of plasma and formed elements including monocytes and lymphocytes, which are important in both antigen presentation and adaptive immune response to influenza.11 However, the formed elements are unlikely to function in the recipients because of allo-rejection.
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Table 4—Comparison of Viral Load and Cytokine Level Between Treatment (H-IVIG) and Control (IVIG) Groups After ICU Admission in All 34 Patients Median Viral load Treatment Control P value IFN-a2 Treatment Control P value IL-1a Treatment Control P value IL-6 Treatment Control P value IL-10 Treatment Control P value IL-15 Treatment Control P value IL-1ra Treatment Control P value MCP-1 Treatment Control P value MIP-1a Treatment Control P value GM-CSF Treatment Control P value TNF-a Treatment Control P value
Day 0
Day 1
Day 2
Day 3
Day 5
5.83 5.34 .45
5.45 5.27 .14
4.46 4.66 .51
4.00 4.58 .06
3.30 4.67 .04
1.53 1.50 .19
1.44 1.30 .09
1.21 1.15 .25
1.28 1.10 .03
0.16 0.16 1.00
1.92 1.79 .61
1.92 1.59 .16
1.58 1.53 .70
1.34 1.43 .57
0.96 1.18 .30
2.15 1.75 .36
1.65 1.65 .52
1.24 1.34 .87
1.00 1.36 .35
0.65 0.98 .22
1.75 1.46 .11
1.63 1.13 .04
1.22 0.97 .06
1.07 1.09 .57
0.79 0.90 .52
1.20 1.15 .26
1.15 1.04 .36
1.11 0.87 .23
1.09 0.82 .07
0.87 0.78 .33
2.07 1.63 .26
1.68 1.36 .04
1.48 1.27 .60
1.29 1.14 .37
0.59 0.79 .83
3.51 3.11 .21
3.49 2.98 .09
2.98 2.94 .67
2.77 2.87 .16
2.67 2.69 .87
1.03 1.02 .31
0.48 0.85 .03
0.48 0.84 .98
0.63 0.88 .78
0.79 0.62 .33
1.70 1.53 .41
1.61 1.33 .07
1.35 1.25 .35
1.23 1.24 .62
1.02 1.07 .72
1.36 1.36 .84
1.22 1.34 .71
1.12 1.33 .048
1.12 1.29 .049
1.15 1.34 .14
Treatment group (H-IVIG): 17 patients; Control group (IVIG): 17 patients. Viral load: log10 copies/mL (lowest detection limit, 900 copies/mL); cytokine/chemokine concentration: log10 pg/mL. GM-CSF 5 granulocyte macrophage colony-stimulating factor, IFN-a2 5 interferon-a2, IL-1ra 5 interleukin 1 receptor antagonist; MCP-1 5 monocyte chemotactic protein-1; MIP-1a 5 macrophage inflammatory protein 1a; TNF-a 5 tumor necrosis factor-a. See Table 1 legend for expansion of other abbreviations.
Therefore, studies have turned to the use of convalescent plasma in human or specific monoclonal antibody in mice models. Convalescent plasma contains factors of the complement cascade, antimicrobial peptides and antibodies. Complement-dependent lytic antibodies can be induced by influenza virus19 and
its vaccine, which may help to control the infection or induce unwanted host cell damage. Plasma also contains important complement regulatory proteins such as CD55, which decreases host cell damage by inhibiting C3 and C5 activation and accelerating their decay.7 Moreover, it contains nonspecific inhibitor of influenza hemagglutinating activity, such as mannose-binding lectin and a-globulins. In addition, the most important component with possible effects on the outcome of severe influenza is the g-globulin fraction, which contains high-avidity neutralizing antibody against the hemagglutinin of the virus,20 nonneutralizing antibodies against other viral components, and IgG2 with opsonizing activity for encapsulated bacteria associated with secondary bacterial pneumonia. H-IVIG may augment antibody-dependent cell-mediated cytotoxicity to suppress viral load and dampen the cytokine/chemokine overactive response. Because the exact components and specificity of the g-globulin fraction of patients recovering from influenza may be different from that of vaccination, convalescent H-IVIG was used instead of postvaccination H-IVIG. The choice was also dictated by the unavailability of vaccine during the period of harvesting plasma in this study. Neuraminidase inhibitors active against the A(H1N1) are the antivirals given to the patients in this study.8 Although enteral oseltamivir and oro-inhaled zanamivir can shorten symptoms by 1 to 2 days in a normal host with nonpneumonic influenza if initiated within 48 h of symptom onset,21 it has never been shown to reduce viral load and mortality in patients with severe influenza pneumonia with respiratory failure. The efficacy of these antiviral agents in these patients with severe late-presenting disease with immunodysregulation is limited. In one of the prospective cohort studies, it was clearly shown that severe cases had delayed clearance of viral load despite treatment by enteral oseltamivir in 34 cases.16 Oseltamivir resistance can quickly develop even in treatment-naive immunosuppressed hosts with high viral load, due to the poor host immune response.22 Thus, passive immunotherapy of H-IVIG or convalescent plasma may be the other feasible treatment option. The main advantage of H-IVIG over normal IVIG is the presence of a high titer of neutralizing antibody, which can neutralize the cell-free virus and inhibit the cell-to-cell spread and cell-associated transmission. In addition, H-IVIG or IVIG could inhibit neutrophil adhesion to endothelium stimulated with IL-1a, thereby preventing endothelial activation.23 The antiinflammatory properties of immunoglobulins may in part be related to blocking IL-1a-dependent leukocyte recruitment and reduction of cytokine mRNA levels. All these mechanisms could have contributed to the prevention of ARDS developing in our patients and explain the more rapid reduction of viral load in the H-IVIG group than the IVIG group.
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Although severe A(H1N1) infection with viremia or extrapulmonary spread was more often reported in patients infected by virus with D222G mutation,24 the majority of such severe disease occurs at the extremes of age and in immunosuppressed, obese, pregnant, and poor premorbid patients.4 Immunodysregulation appears to be the predominant feature shared among these patients. In a mouse model, pregnancy was associated with severe pulmonary damage and cytokine dysregulation.25 Additionally, an IgG2 subclass deficiency has been linked to severe pandemic influenza, especially in pregnant women,6 and lower IgG2 levels in severe disease may be associated with cytokine dysregulation.5 Obesity has been found to be associated with immunodysregulation involving adipokines.26 Immunosuppressive therapy was reported to be an important cause of death for severe A(H1N1) infection in North America.27 Integrated network analyses in a macaque model demonstrated that the mechanism that normally suppresses immune cell signaling and inflammation is ineffective in the A(H1N1) virus infection.28 Moreover, lethal 1918 influenza virus infection in macaques was associated with early dysregulation of the antiviral response and atypical host innate immune response, a feature that may be shared among other virulent influenza viruses.29 Therefore, the presently reported treatment using H-IVIG may achieve both antiviral and immunomodulatory activity, which may be additive to or synergize with the treatment with neuraminidase inhibitors alone in patients with immaturity, dysregulation, and senescence of their immune system. Limitations of the present study included the relatively small number of patients recruited because of the early decline of the A(H1N1) pandemic and the relatively long period required in fractionation of convalescent plasma to H-IVIG. Potential candidates were often excluded because of late presentation to the ICU. Although there were more men in the treatment arm (but not a significant number), data from the Centre for Health Protection showed that more men developed severe diseases from the A(H1N1) pandemic in Hong Kong.30 Nevertheless, the prospective multicenter randomized double-blind nature of this study and the availability of serial viral load and cytokine profiles before and after treatment allowed a robust comparison with the control. This present study is a very unique and valuable opportunity offered by this pandemic, because our comparison is only valid if the control IVIG has only low background antibodies against A(H1N1). In conclusion, the beneficial effects demonstrated in this study appear to be related to the A(H1N1) antibody in the convalescent H-IVIG. This modality of treatment should be considered in future pandemics.11,31
Acknowledgments Author contributions: Drs Hung and Yuen had full access to the data and take responsibility for the manuscript. Dr Hung: contributed to study design, data collection, data analysis, data interpretation, and writing and revision of the manuscript. Dr To: contributed to data analysis, data interpretation, and writing and revision of the manuscript. Dr C.-K. Lee: contributed to study design, data collection, data interpretation, and writing and revision of the manuscript. Dr K.-L. Lee: contributed to data collection and writing of the manuscript. Dr Yan: contributed to study design, data collection, and writing of the manuscript. Dr K. Chan: contributed to data collection and writing of the manuscript. Dr W.-M. Chan: contributed to data collection and writing of the manuscript. Dr Ngai: contributed to data collection and writing of the manuscript. Dr Law: contributed to data collection and writing of the manuscript. Dr Chow: contributed to data collection and writing of the manuscript. Dr R. Liu: contributed to data collection and writing of the manuscript. Dr Lai: contributed to data collection and writing of the manuscript. Dr Lau: contributed to data analysis and writing of the manuscript. Dr S.-H. Liu: contributed to study design and writing of the manuscript. Dr K.-H. Chan: contributed to data collection, data analysis, and writing and revision of the manuscript. Dr Lin: contributed to study design, data collection, and writing of the manuscript. Dr Yuen: contributed to study design, data analysis, data interpretation, and writing and revision of the manuscript. Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article. Role of sponsors: The sponsor had no role in the design of the study, the collection and analysis of the data, or the preparation of the manuscript. Other contributions: We thank the Research Fund for the Control of Infectious Diseases, the Providence Foundation Limited in memory of the late Lui Hac Minh, and the Hospital Authority for supporting this study. We also thank the convalescent plasma donors and colleagues from the Hospital Authority, the Hong Kong Red Cross and Blood Transfusion Service, and the University of Hong Kong who participated in this study. We thank Patrick Li, BSc; Clara Li, BSc; Whitney Ip, BSc; Peggy Chan, BSc; Linda Cheung, BSc; Kiki Yeung, BSc; Cecilia Koo, BSc; and William Chui, BSc, for their important assistance in this study. Additional information: The e-Appendix can be found in the “Supplemental Materials” area of the online article.
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