- Email: [email protected]
2009 Seasonal and H1N1 influenza vaccination compliance in asthmatic children and adults
Letters to the Editor 2009 Seasonal and H1N1 influenza vaccination compliance in asthmatic children and adults To the Editor: Seasonal influenza has been associated with increased morbidity and poor outcomes in asthmatic patients, including superinfection with bacterial pneumonia, respiratory compromise, and hospitalization.1-3 Vaccination against seasonal influenza remains the most efficient and cost-effective method of management for the general public and asthmatic subjects.4 Despite campaigns by public health officials to promote seasonal influenza vaccination, there remains significant public reluctance among persons in high-risk groups.5 In 2009, the global rise of novel H1N1 influenza has caused significant medical and public health concerns. The World Health Organization and Centers for Disease Control and Prevention considered addressing pandemic H1N1 vaccination as a major priority of world health in an effort to control future outbreaks. Particularly concerning is the morbidity and mortality associated with children with chronic respiratory diseases, such as asthma.6 The C. S. Mott Children’s Hospital National Poll on Children’s Health (NPCH) is designed to measure public opinion, perceptions and priorities regarding major health care issues and trends for US children. The goal of the NPCH is to assess issues in a timely fashion using nationally representative scientific probability sample of US households. Periodic surveys are conducted by using an innovative, rigorous, established, Web-based survey technology provided by a private vendor (Knowledge Networks [KN]). KN has established the first online research panel based on probability sampling that covers both the online and offline populations in the United States. The panel members are randomly recruited by telephone, and households are provided with access to the Internet and hardware if needed. The field period for Web-based surveys is short (3-4 weeks). NPCH surveys address a wide variety of children’s health issues, including asthma. In all cases adults are the respondents, and 1 adult is selected per household. The NPCH design oversamples households with parents so that more precise estimates can be made of parental opinions. KN calculates initial weights by using national demographic distributions, as per the most recent Current Population Survey. These weights are adjusted to reduce the effects of potential nonresponse and noncoverage. By using these methods, generalizations can be made from these survey samples to the national US population of parents and to the US population of all adults. Questions focused on previous influenza vaccination in 2008 and the likelihood of vaccination for H1N1 and seasonal influenza in 2009-2010. Subgroup analyses were performed on subjects with a physician’s diagnosis of asthma or who are parents of children with physician-diagnosed asthma. Respondents were asked whether they had a physician’s diagnosis of asthma based on spirometric results, wheezing on multiple occasions, or treatment with long-term controller medications for asthma to determine whether a respondent or parent of a child had asthma. Deidentified weighted survey and demographic data were received from KN. All analyses were conducted with STATA version 10 (StataCorp, College Station, Tex). Frequencies for each survey item were generated and weighted to provide national 166
TABLE I. Intent to vaccinate against influenza: Adults with versus without asthma Did you get the seasonal flu vaccine last year (in the fall/winter of 20082009)?
Yes, flu shot Yes, nasal spray flu vaccine (FluMist) No P 5 .0001
No asthma
Asthma
Overall
36% 1%
54% <1%
39% 1%
63%
46%
60%
Are you planning to get the seasonal flu vaccine this year (in the fall/ winter of 2009-2010)?
Definitely yes or probably yes (combined) Not sure Probably no or definitely no (combined) P 5 .0004
No asthma
Asthma
Overall
42%
61%
44%
16% 42%
14% 25%
16% 40%
Are you planning to get the new H1N1 influenza (‘‘swine flu’’) vaccine this year (in the fall/winter of 2009-2010) for yourself?
Definitely yes or probably yes (combined) Not sure Probably no or definitely no (combined) P 5 .0017
No asthma
Asthma
Overall
33%
44%
35%
26% 41%
32% 24%
26% 39%
estimates, and margins of error were calculated for each item. x2 Analyses were used to test for differences among survey responses. The Medical School Institutional Review Board of the University of Michigan approved the NPCH in July 2009. The survey was fielded from August 13 to 31, 2009. The overall response rate was 68% for all households (n 5 2,365) and 62% in the subset of households with at least 1 child (n 5 1,678). The prevalence of physician-diagnosed asthma was 15% among adults and 18% among parents reporting that 1 or more of their children had a physician’s diagnosis of asthma. This is higher compared with other national reported prevalences of 9.3% in children and 7.9% in adults in 2006, respectively.3 Descriptors of socioeconomic status, race, insurance status, and sex were obtained but on further analysis did not affect the findings of the sample. Both asthmatic adults and parents of asthmatic children do appear to have higher rates of influenza vaccination and vaccination intent for H1N1 than do other subjects (Tables I and II). In this most recent NPCH polling for 2008-2009, there is an improved rate of vaccination (>50%), with improved intent to vaccinate for H1H1 influenza in asthmatic subjects and children (>40%) compared with nonasthmatic subjects. Despite significant vaccination rates in asthmatic adults and children compared with their nonasthmatic counterparts, there still remain large proportions of adults and children who are unlikely to receive
LETTERS TO THE EDITOR 167
J ALLERGY CLIN IMMUNOL VOLUME 126, NUMBER 1
TABLE II. Intent to vaccinate against influenza: Children with versus without asthma
TABLE IV. Respondent reasons for deferring on seasonal influenza vaccination for their child
Did (your child/1 or more of your child[ren]) get the seasonal flu vaccine last year (in the fall/winter of 2008-2009)?
Why are you not planning to get the seasonal flu vaccine for your child(ren) this year?
Families in which no child in the family has asthma Families in which a child in the family has asthma P < .0001
Yes
No asthma
41% 63%
Are you planning on having (your child/1 or more of your children) get seasonal flu vaccine this year (in the fall/winter of 2009-2010)? No asthma Asthma Overall
Definitely yes or probably yes (combined) Not sure Probably no or definitely no (combined) P 5 .006
51% 20% 29%
66% 17% 17%
54% 19% 27%
Are you planning on having (your child/1 or more of your children) get the new H1N1 influenza (‘‘swine flu’’) vaccine this year (in the fall/winter of 2009-2010)? No asthma
No asthma Asthma Overall
Definitely yes or Probably yes (combined) Not sure Probably no or definitely no (combined) P 5 .03
38% 30% 32%
45% 35% 20%
40% 31% 29%
TABLE III. Respondent reasons for deferring seasonal influenza vaccination Why are you not planning to get the seasonal flu vaccine for yourself this year? No asthma
Asthma
Over all
P value
60
52
59
.31
Not worried about getting seasonal influenza
54
45
53
.26
50
39
48
.16
Can take medications to treat it Worried about side effects of the seasonal flu vaccine
Numbers shown are percentages selecting this response among adults who are not planning to get the seasonal flu vaccine (n 5 1,301).
seasonal, H1N1, or both influenza vaccinations. The reasons for vaccination avoidance are remarkably similar across asthma status in adults, as well as in parents of asthmatic children (Tables III and IV). About half of the respondents in the NPCH noted that there was little concern of infection by the viruses, as well as an expectation that medical treatment is widely available for the conditions. These attitudes remained the same across asthma status. About 50% of respondents had concerns about the side effects of vaccination as a major reason to avoid influenza vaccination. For more than 40 years, the Advisory Committee on Immunization Practices has recommended seasonal influenza vaccination for asthmatic subjects because of their higher risk of medical complications and morbidity.1 The burden of influenza on asthmatic subjects has been well documented from the economic burden, medical resource burden, and effect on specific subjects and
Asthma
Over all
P values
52
64
54
.07
Not worried about getting seasonal influenza
60
60
60
.96
52
47
51
.56
Can take medications to treat it Worried about side effects of the seasonal flu vaccine
Numbers shown are percentages selecting this response among parents who do not plan to get seasonal flu vaccine for their children (n 5 800).
their families. Particularly in children, the effect of influenza illness increases health care use and the burden of disease on the child and his or her family.2-4 The NPCH has identified an increased rate of influenza vaccination in asthmatic adults and children compared with that seen in the general population. This is a similar finding to the Centers for Disease Control and Prevention report regarding the 2004-2005 influenza season.7-9 We suspect that public health efforts, continued education, and vaccine access have improved this rate in the last decade. Although the full burden of H1N1 influenza was not yet known at the time this survey was originally fielded in August 2009, public health authorities were concerned that H1N1 flu would particularly threaten the well-being of young patients with respiratory and cardiac comorbidities. A significant limitation of this study was that respondents were queried regarding vaccine intention, and the limited respondent access study mechanism does not permit follow-up to confirm whether respondents were actually vaccinated against either seasonal or H1N1 influenza as the influenza season progressed. Furthermore, the respondent sample, despite being weighted to reflect US Census data, has limitations in terms of the ability to draw conclusions regarding the population with other chronic diseases (ie, the investigators did not oversample based on the presence of chronic conditions). For 2009-2010, the looming H1N1 influenza pandemic added additional urgency to vaccination of the asthmatic population. Even with improved levels of seasonal influenza vaccination approaching the Advisory Committee on Immunization Practices’s Healthy People 2010 goal of 60% vaccination, very few subjects were planning on obtaining H1N1 influenza vaccination despite the risks of infection. In fact, in the NPCH less than 40% of both asthmatic and nonasthmatic respondents intended to receive the vaccination. The discrepancies between seasonal influenza vaccination and pandemic H1N1 vaccination might be due principally to lack of education and to concerns about the vaccine because of its rapid development and deployment on the world stage. The recent appearance of H1N1 influenza has added to the complexity of administering vaccines to the most vulnerable populations. Global issues on vaccine development, pandemic spread, and the influence of rapid media sources for laypeople can greatly influence health perceptions. There are many lessons that can be taken from the H1N1 pandemic, particularly in asthmatic subjects and the general public. Findings in this study about
168 LETTERS TO THE EDITOR
J ALLERGY CLIN IMMUNOL JULY 2010
factors influencing subjects’ intent regarding future influenza vaccination might guide education efforts to improve immunization campaigns for future influenza seasons. Harvey L. Leo, MDa Sarah J. Clark, MPHb Amy T. Butchart, MPHb Dianne C. Singer, MPHb Noreen M. Clark, PhDa Matthew M. Davis, MAPP, MDb From athe School of Public Health Center for Managing Chronic Disease and bthe Department of Pediatrics, Child Health Evaluation and Research Unit (CHEAR), University of Michigan, Ann Arbor, Mich. E-mail: [email protected]. Disclosure of potential conflict of interest: The authors have declared that they have no conflict of interest. REFERENCES 1. Centers for Disease Control and Prevention. Prevention and control of influenza: recommendations of the Advisory Committee on Immunization Practices. MMWR Morb Mortal Wkly Rep 2007;56(RR08):1-54. 2. Hassan F, Lewis TC, Davis MM, Gebremariam A, Dombkowski K. Hospital utilization and costs among children with influenza, 2003. Am J Prev Med 2009;36:292-6. 3. Miller EK, Griffin MR, Edwards KM, Weinberg GA, Szilagyi PG, Staat MA, et al. Influenza burden for children with asthma. Pediatrics 2008;121:1-8. 4. Ampofo K, Gesteland PH, Bender J. Epidemiology, complications, and cost of hospitalization in children with laboratory-confirmed influenza infection. Pediatrics 2006;118:2409-17. 5. Dombkowski KJ, Leung SW, Clark SJ. Physician perspectives regarding annual influenza vaccination among children with asthma. Ambul Pediatr 2008;8:294-9. 6. Jain S, Kamimoto L, Bramley AM, Schmitz AM, Benoit SR, Louie J, et al. Hospitalized patients with 2009 H1N1 influenza in the United States, April-June 2009. N Engl J Med 2009;36:1935-44. 7. Lu PJ, Euler GL, Callahan DB. Influenza vaccination among adults with asthma findings from the 2007 BRFSS survey. Am J Prev Med 2009;37:109-15. 8. Centers for Disease Control and Prevention. Influenza vaccination coverage among children with asthma—United States, 2004-05 influenza season. MMWR Morb Mortal Wkly Rep 2007;56:193-6. 9. Centers for Disease Control and Prevention. Influenza vaccination coverage among persons with asthma—United States, 2005-06 influenza season. MMWR Morb Mortal Wkly Rep 2008;57:653-7. Available online May 24, 2010. doi:10.1016/j.jaci.2010.03.040
Acute exacerbations of chronic rhinosinusitis occur in a distinct seasonal pattern To the Editor: Chronic rhinosinusitis (CRS) is a common and debilitating problem that involves inflammation of the mucosal surfaces lining the nose and sinuses.1 Triggers leading to CRS disease exacerbation are not well characterized. Previous epidemiologic studies have focused on identification of risk factors for having a diagnosis of CRS rather than on risk factors that lead to disease exacerbation in those with an established CRS diagnosis.2,3 Given the insights gained from examining seasonal patterns of asthma exacerbations (a disease often linked to CRS),4 we performed a study that examined the seasonal pattern of CRS exacerbation visits using a unique database that electronically links residents of a single county in southeastern Minnesota (Olmsted County). We performed a retrospective cohort study following patients for up to 2 years (2003-2004) using existing medical records. Patients were identified by using the Rochester Epidemiology Project, an electronically linked medical record system that allows for examination of nearly all health care encounters in Olmsted County, Minnesota. Both sexes and all ages were included. Patients with a diagnosis of specific immune deficiency were excluded. A CRS exacerbation was defined as any visit with
FIG 1. Seasonal pattern of CRS exacerbation visits (n 5 1217). Each bar represents 1 week.
an International Classification of Diseases–Ninth Revisions (ICD-9) code of 473.xx and at least 1 of the following: a prescription for systemic antibiotics, systemic corticosteroid, plans for a semiurgent surgical intervention, emergency department or urgent care visit, or a hospitalization for CRS. Each medical record was reviewed to ensure subjects met inclusion criteria and that the prescribed medications were directly linked with the diagnosis of CRS. The study was approved by the Institutional Review Board of the Olmsted Medical Center and Mayo Clinic Rochester. Descriptive statistics were tabulated for subject demographics and visit frequencies. Seasonality was confirmed by defining 4 equal-length calendar seasons and comparing visit frequencies for equality across seasons with a x2 test. For graphic displays, visit frequencies were smoothed by using a kernel smoother with a Parzen kernel and a bandwidth chosen empirically. One thousand one hundred four patients with a diagnosis of 473.xx were screened, and 800 patients had at least 1 visit that met our definition of a CRS exacerbation. Most subjects were female (65.6%) and white (94%). The mean age of the patients was 37 years, with 17.8% of the subjects defined as children (<18 years old). A total of 1217 CRS exacerbation visits were analyzed. The number of visits per subject over 2003-2004 ranged from 1 to 16, and 607 (75.9%) patients had only 1 CRS exacerbation visit. Primary care provider visits accounted for 55.7% of the visits, whereas allergy (13.7%), otolaryngology (13.1%), and emergency department/urgent care (13.1%) accounted for the nearly all of the remaining visits. Subjects were approximately twice as likely to present for a CRS exacerbation in winter months compared with spring, summer, or fall (P < .0001, Fig 1). The seasonal pattern of increased CRS exacerbation visits in winter was consistent between 2003 and 2004. Age and sex did not significantly affect the seasonal pattern of CRS exacerbation visits, although in both 2003 and 2004, the CRS exacerbation visit frequency of children began to increase earlier (more in fall than winter) compared with that seen in adults (Fig 2). The findings from this study suggest that patients with CRS are most likely to present for disease exacerbation in the winter months in the upper Midwestern United States than in spring, summer, or fall seasons. Using the linked electronic medical
TABLE I. Intent to vaccinate against influenza: Adults with versus without asthma Did you get the seasonal flu vaccine last year (in the fall/winter of 20082009)?
Yes, flu shot Yes, nasal spray flu vaccine (FluMist) No P 5 .0001
No asthma
Asthma
Overall
36% 1%
54% <1%
39% 1%
63%
46%
60%
Are you planning to get the seasonal flu vaccine this year (in the fall/ winter of 2009-2010)?
Definitely yes or probably yes (combined) Not sure Probably no or definitely no (combined) P 5 .0004
No asthma
Asthma
Overall
42%
61%
44%
16% 42%
14% 25%
16% 40%
Are you planning to get the new H1N1 influenza (‘‘swine flu’’) vaccine this year (in the fall/winter of 2009-2010) for yourself?
Definitely yes or probably yes (combined) Not sure Probably no or definitely no (combined) P 5 .0017
No asthma
Asthma
Overall
33%
44%
35%
26% 41%
32% 24%
26% 39%
estimates, and margins of error were calculated for each item. x2 Analyses were used to test for differences among survey responses. The Medical School Institutional Review Board of the University of Michigan approved the NPCH in July 2009. The survey was fielded from August 13 to 31, 2009. The overall response rate was 68% for all households (n 5 2,365) and 62% in the subset of households with at least 1 child (n 5 1,678). The prevalence of physician-diagnosed asthma was 15% among adults and 18% among parents reporting that 1 or more of their children had a physician’s diagnosis of asthma. This is higher compared with other national reported prevalences of 9.3% in children and 7.9% in adults in 2006, respectively.3 Descriptors of socioeconomic status, race, insurance status, and sex were obtained but on further analysis did not affect the findings of the sample. Both asthmatic adults and parents of asthmatic children do appear to have higher rates of influenza vaccination and vaccination intent for H1N1 than do other subjects (Tables I and II). In this most recent NPCH polling for 2008-2009, there is an improved rate of vaccination (>50%), with improved intent to vaccinate for H1H1 influenza in asthmatic subjects and children (>40%) compared with nonasthmatic subjects. Despite significant vaccination rates in asthmatic adults and children compared with their nonasthmatic counterparts, there still remain large proportions of adults and children who are unlikely to receive
LETTERS TO THE EDITOR 167
J ALLERGY CLIN IMMUNOL VOLUME 126, NUMBER 1
TABLE II. Intent to vaccinate against influenza: Children with versus without asthma
TABLE IV. Respondent reasons for deferring on seasonal influenza vaccination for their child
Did (your child/1 or more of your child[ren]) get the seasonal flu vaccine last year (in the fall/winter of 2008-2009)?
Why are you not planning to get the seasonal flu vaccine for your child(ren) this year?
Families in which no child in the family has asthma Families in which a child in the family has asthma P < .0001
Yes
No asthma
41% 63%
Are you planning on having (your child/1 or more of your children) get seasonal flu vaccine this year (in the fall/winter of 2009-2010)? No asthma Asthma Overall
Definitely yes or probably yes (combined) Not sure Probably no or definitely no (combined) P 5 .006
51% 20% 29%
66% 17% 17%
54% 19% 27%
Are you planning on having (your child/1 or more of your children) get the new H1N1 influenza (‘‘swine flu’’) vaccine this year (in the fall/winter of 2009-2010)? No asthma
No asthma Asthma Overall
Definitely yes or Probably yes (combined) Not sure Probably no or definitely no (combined) P 5 .03
38% 30% 32%
45% 35% 20%
40% 31% 29%
TABLE III. Respondent reasons for deferring seasonal influenza vaccination Why are you not planning to get the seasonal flu vaccine for yourself this year? No asthma
Asthma
Over all
P value
60
52
59
.31
Not worried about getting seasonal influenza
54
45
53
.26
50
39
48
.16
Can take medications to treat it Worried about side effects of the seasonal flu vaccine
Numbers shown are percentages selecting this response among adults who are not planning to get the seasonal flu vaccine (n 5 1,301).
seasonal, H1N1, or both influenza vaccinations. The reasons for vaccination avoidance are remarkably similar across asthma status in adults, as well as in parents of asthmatic children (Tables III and IV). About half of the respondents in the NPCH noted that there was little concern of infection by the viruses, as well as an expectation that medical treatment is widely available for the conditions. These attitudes remained the same across asthma status. About 50% of respondents had concerns about the side effects of vaccination as a major reason to avoid influenza vaccination. For more than 40 years, the Advisory Committee on Immunization Practices has recommended seasonal influenza vaccination for asthmatic subjects because of their higher risk of medical complications and morbidity.1 The burden of influenza on asthmatic subjects has been well documented from the economic burden, medical resource burden, and effect on specific subjects and
Asthma
Over all
P values
52
64
54
.07
Not worried about getting seasonal influenza
60
60
60
.96
52
47
51
.56
Can take medications to treat it Worried about side effects of the seasonal flu vaccine
Numbers shown are percentages selecting this response among parents who do not plan to get seasonal flu vaccine for their children (n 5 800).
their families. Particularly in children, the effect of influenza illness increases health care use and the burden of disease on the child and his or her family.2-4 The NPCH has identified an increased rate of influenza vaccination in asthmatic adults and children compared with that seen in the general population. This is a similar finding to the Centers for Disease Control and Prevention report regarding the 2004-2005 influenza season.7-9 We suspect that public health efforts, continued education, and vaccine access have improved this rate in the last decade. Although the full burden of H1N1 influenza was not yet known at the time this survey was originally fielded in August 2009, public health authorities were concerned that H1N1 flu would particularly threaten the well-being of young patients with respiratory and cardiac comorbidities. A significant limitation of this study was that respondents were queried regarding vaccine intention, and the limited respondent access study mechanism does not permit follow-up to confirm whether respondents were actually vaccinated against either seasonal or H1N1 influenza as the influenza season progressed. Furthermore, the respondent sample, despite being weighted to reflect US Census data, has limitations in terms of the ability to draw conclusions regarding the population with other chronic diseases (ie, the investigators did not oversample based on the presence of chronic conditions). For 2009-2010, the looming H1N1 influenza pandemic added additional urgency to vaccination of the asthmatic population. Even with improved levels of seasonal influenza vaccination approaching the Advisory Committee on Immunization Practices’s Healthy People 2010 goal of 60% vaccination, very few subjects were planning on obtaining H1N1 influenza vaccination despite the risks of infection. In fact, in the NPCH less than 40% of both asthmatic and nonasthmatic respondents intended to receive the vaccination. The discrepancies between seasonal influenza vaccination and pandemic H1N1 vaccination might be due principally to lack of education and to concerns about the vaccine because of its rapid development and deployment on the world stage. The recent appearance of H1N1 influenza has added to the complexity of administering vaccines to the most vulnerable populations. Global issues on vaccine development, pandemic spread, and the influence of rapid media sources for laypeople can greatly influence health perceptions. There are many lessons that can be taken from the H1N1 pandemic, particularly in asthmatic subjects and the general public. Findings in this study about
168 LETTERS TO THE EDITOR
J ALLERGY CLIN IMMUNOL JULY 2010
factors influencing subjects’ intent regarding future influenza vaccination might guide education efforts to improve immunization campaigns for future influenza seasons. Harvey L. Leo, MDa Sarah J. Clark, MPHb Amy T. Butchart, MPHb Dianne C. Singer, MPHb Noreen M. Clark, PhDa Matthew M. Davis, MAPP, MDb From athe School of Public Health Center for Managing Chronic Disease and bthe Department of Pediatrics, Child Health Evaluation and Research Unit (CHEAR), University of Michigan, Ann Arbor, Mich. E-mail: [email protected]. Disclosure of potential conflict of interest: The authors have declared that they have no conflict of interest. REFERENCES 1. Centers for Disease Control and Prevention. Prevention and control of influenza: recommendations of the Advisory Committee on Immunization Practices. MMWR Morb Mortal Wkly Rep 2007;56(RR08):1-54. 2. Hassan F, Lewis TC, Davis MM, Gebremariam A, Dombkowski K. Hospital utilization and costs among children with influenza, 2003. Am J Prev Med 2009;36:292-6. 3. Miller EK, Griffin MR, Edwards KM, Weinberg GA, Szilagyi PG, Staat MA, et al. Influenza burden for children with asthma. Pediatrics 2008;121:1-8. 4. Ampofo K, Gesteland PH, Bender J. Epidemiology, complications, and cost of hospitalization in children with laboratory-confirmed influenza infection. Pediatrics 2006;118:2409-17. 5. Dombkowski KJ, Leung SW, Clark SJ. Physician perspectives regarding annual influenza vaccination among children with asthma. Ambul Pediatr 2008;8:294-9. 6. Jain S, Kamimoto L, Bramley AM, Schmitz AM, Benoit SR, Louie J, et al. Hospitalized patients with 2009 H1N1 influenza in the United States, April-June 2009. N Engl J Med 2009;36:1935-44. 7. Lu PJ, Euler GL, Callahan DB. Influenza vaccination among adults with asthma findings from the 2007 BRFSS survey. Am J Prev Med 2009;37:109-15. 8. Centers for Disease Control and Prevention. Influenza vaccination coverage among children with asthma—United States, 2004-05 influenza season. MMWR Morb Mortal Wkly Rep 2007;56:193-6. 9. Centers for Disease Control and Prevention. Influenza vaccination coverage among persons with asthma—United States, 2005-06 influenza season. MMWR Morb Mortal Wkly Rep 2008;57:653-7. Available online May 24, 2010. doi:10.1016/j.jaci.2010.03.040
Acute exacerbations of chronic rhinosinusitis occur in a distinct seasonal pattern To the Editor: Chronic rhinosinusitis (CRS) is a common and debilitating problem that involves inflammation of the mucosal surfaces lining the nose and sinuses.1 Triggers leading to CRS disease exacerbation are not well characterized. Previous epidemiologic studies have focused on identification of risk factors for having a diagnosis of CRS rather than on risk factors that lead to disease exacerbation in those with an established CRS diagnosis.2,3 Given the insights gained from examining seasonal patterns of asthma exacerbations (a disease often linked to CRS),4 we performed a study that examined the seasonal pattern of CRS exacerbation visits using a unique database that electronically links residents of a single county in southeastern Minnesota (Olmsted County). We performed a retrospective cohort study following patients for up to 2 years (2003-2004) using existing medical records. Patients were identified by using the Rochester Epidemiology Project, an electronically linked medical record system that allows for examination of nearly all health care encounters in Olmsted County, Minnesota. Both sexes and all ages were included. Patients with a diagnosis of specific immune deficiency were excluded. A CRS exacerbation was defined as any visit with
FIG 1. Seasonal pattern of CRS exacerbation visits (n 5 1217). Each bar represents 1 week.
an International Classification of Diseases–Ninth Revisions (ICD-9) code of 473.xx and at least 1 of the following: a prescription for systemic antibiotics, systemic corticosteroid, plans for a semiurgent surgical intervention, emergency department or urgent care visit, or a hospitalization for CRS. Each medical record was reviewed to ensure subjects met inclusion criteria and that the prescribed medications were directly linked with the diagnosis of CRS. The study was approved by the Institutional Review Board of the Olmsted Medical Center and Mayo Clinic Rochester. Descriptive statistics were tabulated for subject demographics and visit frequencies. Seasonality was confirmed by defining 4 equal-length calendar seasons and comparing visit frequencies for equality across seasons with a x2 test. For graphic displays, visit frequencies were smoothed by using a kernel smoother with a Parzen kernel and a bandwidth chosen empirically. One thousand one hundred four patients with a diagnosis of 473.xx were screened, and 800 patients had at least 1 visit that met our definition of a CRS exacerbation. Most subjects were female (65.6%) and white (94%). The mean age of the patients was 37 years, with 17.8% of the subjects defined as children (<18 years old). A total of 1217 CRS exacerbation visits were analyzed. The number of visits per subject over 2003-2004 ranged from 1 to 16, and 607 (75.9%) patients had only 1 CRS exacerbation visit. Primary care provider visits accounted for 55.7% of the visits, whereas allergy (13.7%), otolaryngology (13.1%), and emergency department/urgent care (13.1%) accounted for the nearly all of the remaining visits. Subjects were approximately twice as likely to present for a CRS exacerbation in winter months compared with spring, summer, or fall (P < .0001, Fig 1). The seasonal pattern of increased CRS exacerbation visits in winter was consistent between 2003 and 2004. Age and sex did not significantly affect the seasonal pattern of CRS exacerbation visits, although in both 2003 and 2004, the CRS exacerbation visit frequency of children began to increase earlier (more in fall than winter) compared with that seen in adults (Fig 2). The findings from this study suggest that patients with CRS are most likely to present for disease exacerbation in the winter months in the upper Midwestern United States than in spring, summer, or fall seasons. Using the linked electronic medical