- Email: [email protected]
Prevalence of nosocomial infections in hospitals in Norway, 2002 and 2003
Journal of Hospital Infection (2005) 60, 40–45
www.elsevierhealth.com/journals/jhin
Prevalence of nosocomial infections in hospitals in Norway, 2002 and 2003 H.M. Eriksena,b,*, B.G. Iversena, P. Aavitslanda a
Norwegian Institute of Public Health, P. O. Box 4404, Nydalen 0403 Oslo, Norway The European Programme for Intervention Epidemiology Training, Stockholm, Sweden
b
Received 28 May 2004; accepted 23 September 2004
KEYWORDS Nosocomial infections; Hospital infections; Prevalence; Norway
Summary The Norwegian Institute of Public Health initiated a national surveillance system for nosocomial infections in 2002. The system is based on two annual one-day prevalence surveys recording the four most common types of nosocomial infection: urinary tract infections; lower respiratory tract infections; surgical site infections and septicaemia. All acute care hospitals in Norway (NZ76) were invited to participate in the four surveys in 2002 and 2003. The total prevalence of the four recorded nosocomial infections varied between 5.1% and 5.4% in the four surveys. In all surveys, nosocomial infections were located most frequently in the urinary tract (34%), followed by the lower respiratory tract (29%), surgical sites (28%) and septicaemia (8%). The prevalence surveys give a brief overview of the burden and distribution of nosocomial infections. The results can be used to prioritize further infection control measures and more detailed incidence surveillance of nosocomial infections. Q 2004 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.
Introduction Nosocomial infections are common causes of illness and death among hospitalized patients. Surveillance of nosocomial infections is regarded as an essential part of infection control.1 In Norway in
* Corresponding author. Address: Norwegian Institute of Public Health, P. O. Box 4404, Nydalen 0403 Oslo, Norway. Tel.: C47 22 04 26 25. E-mail address: [email protected]
1996, health authorities considered it desirable to assess the problem of nosocomial infections in health institutions on a regular, national basis. A regulation was passed that all healthcare institutions should have a surveillance system for nosocomial infections. Due to resource limitations, a decision was made to implement a surveillance system based on two one-day prevalence surveys per year. The objectives were to measure the baseline prevalence of infections, monitor trends and identify the distribution of nosocomial infections in hospitals in Norway, and to study the
0195-6701/$ - see front matter Q 2004 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2004.09.038
Prevalence of nosocomial infections in Norway Table I
41
Modified Centers for Disease Control and Prevention case definitions of hospital infections
Hospital infection: an infection that is associated with a stay in a health institution and that was not present or in the incubation period (Z48 h) at the time of admission. Urinary tract infection: clinical signs plus at least one of the following criteria: 1. More than 10 000 bacteria/mL urine and not more than two species of bacteria identified by a qualitative technique; 2. Positive bacterial culture in urine collected by sterile suprapubic technique. Clinical signs include: fever O38 8C, urgency, frequency, dysuria or subrapubic tenderness. Lower respiratory tract infection: cough, fever and purulent sputum independent of result of culture from sputum and/or chest radiographic examination. If no purulent sputum but chest radiographic examination shows typical signs of infection, the condition should be reported as lower respiratory tract infection. Superficial surgical site infection: visible purulent draining from the skin or subcutaneous tissue of the incision and independent from results of culture. It is not a surgical site infection if the only signs are redness and localized swelling. In addition, purulent discharge must be demonstrated by spontaneous drainage or incision. Deep surgical site infection: an inflammatory reaction or purulent drainage from the deep incision (under fascial layer, intra-abdominal, intramuscular, osteitis, arteritis, etc.) diagnosed invasively (operation) or non-invasively (ultrasound, X-ray). Reporting instructions: note that surgical site infection occurs within 30 days of the operative procedure if no implant is left in place or within one year if implant is in place and the infection appears to be related to the operative procedure. Sepsis: defined by clinical picture with reduced general condition and fever, possible central nervous system symptoms (stupor, confusion, hyperventilation etc.) and/or haemodynamic symptoms (hypotension and shock).
further need for infection control measures and areas where incidence surveillance would be more sufficient. The Norwegian Institute of Public Health (NIPH) co-ordinated the surveillance. This paper presents the results of the four surveys performed in 2002 and 2003.
Methods All acute care hospitals (NZ76), except those exclusively for psychiatric patients, in Norway were invited to participate in two prevalence surveys each year. The surveys were limited to the four most common types of nosocomial infection: urinary tract infections; lower respiratory tract infections; surgical site infections and septicaemia. The NIPH supplied the hospitals with forms, written instructions and case definitions prior to each survey. The surveys were conducted on a Wednesday in the second week of June and the third week of October. All inpatients in the institution at 8 a.m. were included. In each ward, a physician and a nurse were assigned to collect data on the day of survey. They were to confirm the presence of nosocomial infections by on-site observation. The hospitals’ infection control nurses, all of whom had been trained at the NIPH, were responsible for local training sessions in the surveillance methodology. They also controlled the quality of the data recorded in the wards.
The infections were defined based on a slight modification of the Centers for Disease Control and Prevention (CDC)’s criteria (see Table I). These definitions have been used in previous prevalence surveys in Norway. We chose the modified version to allow better comparison of new and old data. Only symptomatic urinary tract infections were recorded. Infections present or in the incubation period (Z48 h) at the time of hospital admission were not recorded as nosocomial. Infections at more than one site on the patient were reported as separate infections. On the day of each survey, the total number of inpatients and the number of patients who had undergone an operation within the last 30 days (one year if an implant was inserted) was recorded. The number of nosocomial infections was identified. It was also recorded whether the infection was associated with current hospital stay or a previous stay in another health institution. On a voluntary basis, hospitals may record data on medical device utilization and other individual risk factors for use in the local infection control efforts. These data, however, are not part of the national surveys and are not transmitted to the NIPH. Nosocomial infections were recorded separately for the different medical specialities. Epidemiological data such as the size of the hospital were also recorded. Summary records for each hospital were made by an infection control nurse and sent to the NIPH for processing. Obvious errors in the records were discussed with the infection control nurse in
42 Table II 2003
H.M. Eriksen et al. Prevalence (%) of nosocomial infections with 95% confidence intervals in hospitals in Norway, 2002 and
Site of infection Urinary tract Surgical site (denominator: all patients) Surgical site (denominator: those operated) Lower respiratory tract Septicaemia Total prevalence Number of patients
June 2002
October 2002
June 2003
October 2003
1.8 (1.5–2.0) 1.5 (1.3–1.7)
1.9 (1.6–2.1) 1.5 (1.3–1.7)
2.0 (1.8–2.2) 1.5 (1.3–1.7)
1.7 (1.5–1.9) 1.4 (1.2–1.6)
5.3 (4.5–6.2)
6.1 (5.3–7.0)
5.7 (4.9–6.5)
5.8 (5.0–6.7)
1.7 (1.5–1.9) 0.5 (0.4–0.6) 5.3 (4.9–5.7) 11 517
1.6 (1.3–1.8) 0.5 (0.4–0.6) 5.4 (5.1–5.8) 12 736
1.5 (1.3–1.7) 0.5 (0.4–0.6) 5.4 (5.0–5.8) 12 747
1.6 (1.3–1.8) 0.4 (0.3–0.5) 5.1 (4.7–5.5) 12 257
the reporting hospitals and corrected by comparison with the hospitals’ original data. We recorded, controlled and analysed the data in a custom-made database in EpiInfo version 6.0. This programme was used to calculate prevalence and 95% confidence intervals (CI). Shortly after each survey, the main results were published in a newsletter to participating hospitals and on the NIPH website. An annual report is also distributed to all hospitals. Infection control personnel are responsible for assessing and responding to the results for their hospital.
Results The number of hospitals participating in the four surveys in 2002 and 2003 varied from 59 to 71. Between 11 517 and 12 747 patients were included in each of the surveys. The national prevalence of the four recorded nosocomial infections varied between 5.1% and 5.4% (Table II). The prevalence ranged from 0 to 16.7% between facilities, and the largest range was found in small hospitals. The total prevalence varied with the size of the hospital (Table III). Most nosocomial infections (80%) were associated with the current hospital stay. In all surveys, nosocomial infections were located most frequently in the urinary tract (34%), followed by the lower respiratory tract (about 29%), surgical sites (28%) and septicaemia (between 8% and 9.2%). Prevalence varied between the different specialities frequently found in hospitals (Table IV). Table IV shows the results from the June 2003 survey; results from the other surveys showed a similar pattern and there were no significant differences. The total prevalence of nosocomial infections was greatest in intensive care wards, and the lowest prevalence was found in psychiatric wards.
Discussion The overall prevalence of the four most common nosocomial infections in non-psychiatric hospitals in Norway in 2002 and 2003 was between 5.1% and 5.4%. Urinary tract infections accounted for 34% of the infections. Prevalence varied between the different medical specialities. Differences in methodologies and patient population do not allow for stringent comparison of prevalence between hospitals in Norway and those in other countries. However, results from elsewhere can indicate consistency of data. The prevalence rate of nosocomial infections in Norway appears to be of the same magnitude as that reported in surveys in other European countries.2–6 Regardless of methodological differences, urinary tract infections were the most frequent nosocomial infection followed by lower respiratory tract infection and surgical site infection, as found in our survey data. These similarities indicate that the prevalence identified is typical.2–6 An objective of repeated prevalence surveys is to identify changes in distribution and prevalence of nosocomial infections over time. Between 1979 and 2001, four nationwide prevalence surveys were conducted in Norway. The total prevalence of the four main types of infection was 6.9% in 1979 and 6.1% in 1997. The prevalence of urinary tract infections decreased from 3.8 (95% CIZ3.4–4.2) in 1979 to 2.1 (95% CIZ1.9–2.4) in 1997, while the prevalence of septicaemia increased from 0.2 (95% CIZ0.1–0.3) in 1979 to 0.8% (95% CIZ0.7–1.0) in 1997. In 1985 and 1997, surgical site infections were found in 4.6% and 6.3% of patients who had undergone surgery, respectively. The prevalence of lower respiratory tract infections was of the same magnitude in all four surveys.7–10 This change in trends in total infections and urinary tract infections from 1979 to the present time may be due to improved infection control.
24 9 15a 5 7 60 (0–9.3) (1.7–12.2) (1.5–6.7) (3.2–8.9) (2.9–6.7) (0-12.2) 3.6 3.8 5.5 5.0 4.8 5.1 a
Three hospitals had just below 200 patients in all other surveys, but just above 200 patients in this survey.
35 12 11 6 7 71 4.1 (0–16.7) 5.7 (2.7–11.9) 5.6 (2.7–9.9) 5.6 (2.5–10.0) 5.7 (3.5–7.1) 5.4 (0–16.7) 32 12 12 5 7 68 (0–14.7) (1.6–9.5) (1.9–8.4) (3.1–7.0) (4.5–6.8) (0–14.7) 5.9 4.7 5.6 5.3 5.4 5.4 4.2 (0–16.7) 4.4 (0.9–8.7) 4.5 (0.9–7.4) 6.2 (3.5–8.0) 5.7 (3.5–9.2) 5.3 (0–16.7) 0–99 100–199 200–299 300–399 More than 400 Total prevalence
32 12 12 4 7 67
No. of hospitals Prevalence (range) in October 2003 (%) No. of hospitals Prevalence (range) in June 2003 (%) No. of hospitals Prevalence (range) in October 2002 (%) No. of hospitals Prevalence (range) in June 2002 (%) Groups of hospitals by number of patients
Table III
Average (range) prevalence of nosocomial infections by size (number of patients on the day of survey) in hospitals in Norway, 2002 and 2003
Prevalence of nosocomial infections in Norway
43 However, changes in the patient case mix and shortening of hospital stays may also have contributed to the change in trends. Also, the survey method changed slightly during the period. Prevalence seemed to plateau in 2002 and 2003. A potential weakness of our surveillance system is that several people are involved in registration. We have not held national training courses to ensure similar understanding of the survey protocol, and definitions of the nosocomial infections. However, all the infection control nurses were trained at the NIPH in surveillance methodology. Also, in most hospitals, infection control nurses hold a training session, and are available on the day of the survey to help interpret the definitions of infections. In addition, the same set of definitions and case finding methods were used by all institutions in our study. Gastmeier et al. showed that despite the use of very specific CDC criteria, there could still be subjectivity in the diagnosis of nosocomial infections. They suggested that even the use of less specific criteria than those of the CDC, or if the investigators are less qualified or well trained, could result in the investigator effect being even more marked.11 If, and to what degree, our modified definitions are less specific than the originals, is not known, but the main features of the CDC case definitions are included. The investigator effect is not known. Thus, the CDC case definitions subdivide surgical site infections into three categories. In our modified version, although only superficial and deep surgical site infections are recorded, the definition of deep surgical site infections includes both deep infections and infections in organs and spaces. The main advantage of our surveys is the high response rate. This excludes one major potential source of bias in the results. We believe that this high response rate was made possible through the quality of the instructions and the limited number of data elements to be recorded for each patient. A wide range of prevalence was reported from the different hospitals (0–16.7%). The widest range was found within institutions with less than 100 patients. Prevalence surveys thus seem most suitable for larger institutions. All patients were registered in the department in which they were resident on the day of the survey, irrespective of patient transfer since onset of infection. We made no attempt to assign infected patients retrospectively to the ward, department or hospital where the infections were most probably acquired. Such a procedure would have added complexity and potential for bias to the system. Thus, some departments or hospitals that receive
Number of nosocomial infections by type of infection and speciality in hospitals in Norway, June 2003
Department typea
Number of patients
Number of operations
Number of UTIs
Number of LRTIs
Number of superficial SSIs
Number of deep SSIs
Number of septicaemias
1973 172 100 175 204 659 232 359 206 468 1068 43 622 236 1224 100 320 75 4 126
116 6 3 2 23 34 22 11 8 60 529 14 252 126 800 66 151 50 4 53 62 19 133 89 147 107 62 13 34 4 93 54 41 82 1
44 5 0 3 12 12 2 3 8 11 22 0 9 7 40 1 10 2 0 2 5 1 0 1 1 1 1 1 16 3 17 9 0 0 5
36 1 4 0 8 13 4 10 2 7 12 0 8 5 12 1 0 0 0 4 16 11 14 1 0 0 2 0 6 1 4 2 0 4 0
3 1 0 0 0 1 1 4 0 2 7 0 4 5 12 0 2 1 0 0 2 0 0 1 1 4 2 1 1 0 1 3 0 1 0
12 1 0 1 2 1 6 1 0 3 15 0 14 4 42 1 0 1 0 0 5 2 5 0 2 0 4 0 4 0 1 0 0 0 0
6 1 0 2 1 1 3 0 3 1 1 0 2 1 3 0 1 0 0 0 5 1 4 0 2 1 7 7 0 1 0 0 0 0 0
3271
254
188
60
127
60
187 167 408 278 752 473 176 348 62 434 294 86 187 399 12 747
CI, confidence interval; UTI, urinary tract infection; LRTI, lower respiratory tract infection; SSI, surgical site infection; ENT, ear, nose and throat. a Hospitals that did not provide results by speciality are included in the total prevalence.
Total prevalence (%) (95% CI) 5.1 8.7 4.0 3.4 11.3 4.2 6.9 5.0 6.3 5.1 5.3 5.9 9.3 8.9 3.0 4.0 5.3 4.8 25.4 8.0 13.8 0.7 2.2 0.8 3.4 5.1 7.6 8.1 5.3 4.8 2.7 1.3
(4.1–6.1) (4.5–12.9) (0.2–7.8) (0.7–6.1) (6.9–15.6) (2.7–5.8) (3.6–10.1) (2.8–7.3) (3.0–9.6) (3.1–7.1) (4.0–6.7) – (4.1–7.8) (5.6–13.0) (7.3–10.5) (0.0–6.3) (1.9–6.2) (0.3–10.4) – (1.0–8.5) (17.9–32.9) (4.1–11.9) (8.6–19.0) (0.0–1.6) (0.5–3.9) (0.2–1.4) (1.8–5.0) (1.9–8.4) (5.0–10.6) (1.3–14.8) (3.2–7.4) (2.3–7.2) – (0.4–5.0) (0.2–2.3)
5.4 (5.0–5.8)
H.M. Eriksen et al.
General medicine Haematology Endocrinology Gastroenterology Geriatric Cardiovascular diseases Infectious diseases Pulmonary diseases Nephrology Oncology General surgery Paediatric surgery Gastroenterological surgery Cardiovascular surgery Orthopaedic surgery Thoracic surgery Urology Plastic surgery Maxillofacial surgery Neurosurgery Intensive medicine Medical intensive care Surgical intensive care Gynaecology/obstetric Gynaecology Newborn ward General paediatrics Neonatal ward Neurology Skin diseases Rehabilitation Rheumatology Ophthalmology ENT ward Psychiatry Totala
44
Table IV
Prevalence of nosocomial infections in Norway infected patients may feel that their rates are distorted. We explain this caveat when we present the data. Health authorities used the results from the June 2003 survey to rank hospital quality and for interhospital comparison. This may be misleading due to factors such as differences in case mix between hospitals and transfers of infected patients, which are not adjusted in these surveys. Many hospitals felt that they were wrongly designated as a hospital with an infection problem. This may be why fewer hospitals participated in the following survey. We argue that results from prevalence surveys are useful to gain an overview of the distribution and magnitude of nosocomial infections, but that the results must be compared with caution. If ranking hospitals by infection and control measures, results from incidence surveillance or indicators such as ratio of infection control personnel:patient beds and implementation of infection control programmes might give a more accurate picture than using results from prevalence surveys. We found prevalence surveys to be an acceptable, cheap and easy way of assessing nosocomial infection rates in Norwegian hospitals. Nurses and physicians reported that an additional benefit of the surveys involved staff education and awareness of the local problem with nosocomial infections. The surveys have been a contributing factor to implementing infection control measures such as infection control programmes and incidence surveillance systems. The data have also been used for political and administrative purposes, and as an argument for more resources for infection control in hospitals. The Government’s recent ‘Plan of action to prevent nosocomial infections 2004–2006’ made extensive use of the results from the prevalence surveys.
45
Acknowledgements We thank all the physicians and nurses who contributed to these surveys.
Reference 1. Mayhall CG. In: Mayhall CG, editor. Hospital epidemiology and infection control. Philadelphia, PA: Lippincott Williams & Wilkins; 1999. p. 157—247. 2. The French Prevalence Group. Prevalence of nosocomial infections in France: results of the nationwide survey in 1996. J Hosp Infect 2000;46:186—93. 3. Sax H. Nationwide surveillance of nosocomial infections in Switzerland-methods and results of the Swiss Nosocomial Infection Prevalence Studies (SNIP) in 1999 and 2002. Ther Umsch 2004;61:197—203. 4. Nicastri E, Petrosillo N, Martini L, Larosa M, Gesu GP, Ippolito G. Prevalence of nosocomial infections in 15 Italian hospitals: first point prevalance study for the INF-NOS project. Infection 2003;31(Suppl. 2):10—15. 5. Vaque J, Rossello J, Arribas JL. Prevalence of nosocomial infections in Spain: EPINE study 1990–1997. EPINE working group. J Hosp Infect 1999;43:S105—S111. 6. Gastmeier P, Kampf G, Wischnewski N, et al. Prevalence of nosocomial infections in representative German hospitals. J Hosp Infect 1998;38:37—49. 7. Aavitsland P, Stormark M, Lystad A. Hospital-acquired infections in Norway: a national prevalence survey in 1991. Scand J Infect Dis 1992;24:477—483. 8. Hovig B, Lystad A, Opsjon H. A prevalence survey of infections among hospitalized patients in Norway. NIPH Ann 1981;4:49—60. 9. Lystad A, Stormark M. A national prevalence study of hospital acquired infections in Norway. Edizioni riviste scientifiche. Acts from the International Symposium on the Control of Hospital Infections. Firenze, Italy, 1987. p. 25—27. 10. Scheel O, Stormark M. National prevalence survey on hospital infections in Norway. J Hosp Infect 1999;41: 331—335. 11. Gastmeier P, Kampf G, Hauer T, et al. Experience with two validation methods in a prevalence survey on nosocomial infections. Infect Control Hosp Epidemiol 1998;19:668—673.
www.elsevierhealth.com/journals/jhin
Prevalence of nosocomial infections in hospitals in Norway, 2002 and 2003 H.M. Eriksena,b,*, B.G. Iversena, P. Aavitslanda a
Norwegian Institute of Public Health, P. O. Box 4404, Nydalen 0403 Oslo, Norway The European Programme for Intervention Epidemiology Training, Stockholm, Sweden
b
Received 28 May 2004; accepted 23 September 2004
KEYWORDS Nosocomial infections; Hospital infections; Prevalence; Norway
Summary The Norwegian Institute of Public Health initiated a national surveillance system for nosocomial infections in 2002. The system is based on two annual one-day prevalence surveys recording the four most common types of nosocomial infection: urinary tract infections; lower respiratory tract infections; surgical site infections and septicaemia. All acute care hospitals in Norway (NZ76) were invited to participate in the four surveys in 2002 and 2003. The total prevalence of the four recorded nosocomial infections varied between 5.1% and 5.4% in the four surveys. In all surveys, nosocomial infections were located most frequently in the urinary tract (34%), followed by the lower respiratory tract (29%), surgical sites (28%) and septicaemia (8%). The prevalence surveys give a brief overview of the burden and distribution of nosocomial infections. The results can be used to prioritize further infection control measures and more detailed incidence surveillance of nosocomial infections. Q 2004 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.
Introduction Nosocomial infections are common causes of illness and death among hospitalized patients. Surveillance of nosocomial infections is regarded as an essential part of infection control.1 In Norway in
* Corresponding author. Address: Norwegian Institute of Public Health, P. O. Box 4404, Nydalen 0403 Oslo, Norway. Tel.: C47 22 04 26 25. E-mail address: [email protected]
1996, health authorities considered it desirable to assess the problem of nosocomial infections in health institutions on a regular, national basis. A regulation was passed that all healthcare institutions should have a surveillance system for nosocomial infections. Due to resource limitations, a decision was made to implement a surveillance system based on two one-day prevalence surveys per year. The objectives were to measure the baseline prevalence of infections, monitor trends and identify the distribution of nosocomial infections in hospitals in Norway, and to study the
0195-6701/$ - see front matter Q 2004 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2004.09.038
Prevalence of nosocomial infections in Norway Table I
41
Modified Centers for Disease Control and Prevention case definitions of hospital infections
Hospital infection: an infection that is associated with a stay in a health institution and that was not present or in the incubation period (Z48 h) at the time of admission. Urinary tract infection: clinical signs plus at least one of the following criteria: 1. More than 10 000 bacteria/mL urine and not more than two species of bacteria identified by a qualitative technique; 2. Positive bacterial culture in urine collected by sterile suprapubic technique. Clinical signs include: fever O38 8C, urgency, frequency, dysuria or subrapubic tenderness. Lower respiratory tract infection: cough, fever and purulent sputum independent of result of culture from sputum and/or chest radiographic examination. If no purulent sputum but chest radiographic examination shows typical signs of infection, the condition should be reported as lower respiratory tract infection. Superficial surgical site infection: visible purulent draining from the skin or subcutaneous tissue of the incision and independent from results of culture. It is not a surgical site infection if the only signs are redness and localized swelling. In addition, purulent discharge must be demonstrated by spontaneous drainage or incision. Deep surgical site infection: an inflammatory reaction or purulent drainage from the deep incision (under fascial layer, intra-abdominal, intramuscular, osteitis, arteritis, etc.) diagnosed invasively (operation) or non-invasively (ultrasound, X-ray). Reporting instructions: note that surgical site infection occurs within 30 days of the operative procedure if no implant is left in place or within one year if implant is in place and the infection appears to be related to the operative procedure. Sepsis: defined by clinical picture with reduced general condition and fever, possible central nervous system symptoms (stupor, confusion, hyperventilation etc.) and/or haemodynamic symptoms (hypotension and shock).
further need for infection control measures and areas where incidence surveillance would be more sufficient. The Norwegian Institute of Public Health (NIPH) co-ordinated the surveillance. This paper presents the results of the four surveys performed in 2002 and 2003.
Methods All acute care hospitals (NZ76), except those exclusively for psychiatric patients, in Norway were invited to participate in two prevalence surveys each year. The surveys were limited to the four most common types of nosocomial infection: urinary tract infections; lower respiratory tract infections; surgical site infections and septicaemia. The NIPH supplied the hospitals with forms, written instructions and case definitions prior to each survey. The surveys were conducted on a Wednesday in the second week of June and the third week of October. All inpatients in the institution at 8 a.m. were included. In each ward, a physician and a nurse were assigned to collect data on the day of survey. They were to confirm the presence of nosocomial infections by on-site observation. The hospitals’ infection control nurses, all of whom had been trained at the NIPH, were responsible for local training sessions in the surveillance methodology. They also controlled the quality of the data recorded in the wards.
The infections were defined based on a slight modification of the Centers for Disease Control and Prevention (CDC)’s criteria (see Table I). These definitions have been used in previous prevalence surveys in Norway. We chose the modified version to allow better comparison of new and old data. Only symptomatic urinary tract infections were recorded. Infections present or in the incubation period (Z48 h) at the time of hospital admission were not recorded as nosocomial. Infections at more than one site on the patient were reported as separate infections. On the day of each survey, the total number of inpatients and the number of patients who had undergone an operation within the last 30 days (one year if an implant was inserted) was recorded. The number of nosocomial infections was identified. It was also recorded whether the infection was associated with current hospital stay or a previous stay in another health institution. On a voluntary basis, hospitals may record data on medical device utilization and other individual risk factors for use in the local infection control efforts. These data, however, are not part of the national surveys and are not transmitted to the NIPH. Nosocomial infections were recorded separately for the different medical specialities. Epidemiological data such as the size of the hospital were also recorded. Summary records for each hospital were made by an infection control nurse and sent to the NIPH for processing. Obvious errors in the records were discussed with the infection control nurse in
42 Table II 2003
H.M. Eriksen et al. Prevalence (%) of nosocomial infections with 95% confidence intervals in hospitals in Norway, 2002 and
Site of infection Urinary tract Surgical site (denominator: all patients) Surgical site (denominator: those operated) Lower respiratory tract Septicaemia Total prevalence Number of patients
June 2002
October 2002
June 2003
October 2003
1.8 (1.5–2.0) 1.5 (1.3–1.7)
1.9 (1.6–2.1) 1.5 (1.3–1.7)
2.0 (1.8–2.2) 1.5 (1.3–1.7)
1.7 (1.5–1.9) 1.4 (1.2–1.6)
5.3 (4.5–6.2)
6.1 (5.3–7.0)
5.7 (4.9–6.5)
5.8 (5.0–6.7)
1.7 (1.5–1.9) 0.5 (0.4–0.6) 5.3 (4.9–5.7) 11 517
1.6 (1.3–1.8) 0.5 (0.4–0.6) 5.4 (5.1–5.8) 12 736
1.5 (1.3–1.7) 0.5 (0.4–0.6) 5.4 (5.0–5.8) 12 747
1.6 (1.3–1.8) 0.4 (0.3–0.5) 5.1 (4.7–5.5) 12 257
the reporting hospitals and corrected by comparison with the hospitals’ original data. We recorded, controlled and analysed the data in a custom-made database in EpiInfo version 6.0. This programme was used to calculate prevalence and 95% confidence intervals (CI). Shortly after each survey, the main results were published in a newsletter to participating hospitals and on the NIPH website. An annual report is also distributed to all hospitals. Infection control personnel are responsible for assessing and responding to the results for their hospital.
Results The number of hospitals participating in the four surveys in 2002 and 2003 varied from 59 to 71. Between 11 517 and 12 747 patients were included in each of the surveys. The national prevalence of the four recorded nosocomial infections varied between 5.1% and 5.4% (Table II). The prevalence ranged from 0 to 16.7% between facilities, and the largest range was found in small hospitals. The total prevalence varied with the size of the hospital (Table III). Most nosocomial infections (80%) were associated with the current hospital stay. In all surveys, nosocomial infections were located most frequently in the urinary tract (34%), followed by the lower respiratory tract (about 29%), surgical sites (28%) and septicaemia (between 8% and 9.2%). Prevalence varied between the different specialities frequently found in hospitals (Table IV). Table IV shows the results from the June 2003 survey; results from the other surveys showed a similar pattern and there were no significant differences. The total prevalence of nosocomial infections was greatest in intensive care wards, and the lowest prevalence was found in psychiatric wards.
Discussion The overall prevalence of the four most common nosocomial infections in non-psychiatric hospitals in Norway in 2002 and 2003 was between 5.1% and 5.4%. Urinary tract infections accounted for 34% of the infections. Prevalence varied between the different medical specialities. Differences in methodologies and patient population do not allow for stringent comparison of prevalence between hospitals in Norway and those in other countries. However, results from elsewhere can indicate consistency of data. The prevalence rate of nosocomial infections in Norway appears to be of the same magnitude as that reported in surveys in other European countries.2–6 Regardless of methodological differences, urinary tract infections were the most frequent nosocomial infection followed by lower respiratory tract infection and surgical site infection, as found in our survey data. These similarities indicate that the prevalence identified is typical.2–6 An objective of repeated prevalence surveys is to identify changes in distribution and prevalence of nosocomial infections over time. Between 1979 and 2001, four nationwide prevalence surveys were conducted in Norway. The total prevalence of the four main types of infection was 6.9% in 1979 and 6.1% in 1997. The prevalence of urinary tract infections decreased from 3.8 (95% CIZ3.4–4.2) in 1979 to 2.1 (95% CIZ1.9–2.4) in 1997, while the prevalence of septicaemia increased from 0.2 (95% CIZ0.1–0.3) in 1979 to 0.8% (95% CIZ0.7–1.0) in 1997. In 1985 and 1997, surgical site infections were found in 4.6% and 6.3% of patients who had undergone surgery, respectively. The prevalence of lower respiratory tract infections was of the same magnitude in all four surveys.7–10 This change in trends in total infections and urinary tract infections from 1979 to the present time may be due to improved infection control.
24 9 15a 5 7 60 (0–9.3) (1.7–12.2) (1.5–6.7) (3.2–8.9) (2.9–6.7) (0-12.2) 3.6 3.8 5.5 5.0 4.8 5.1 a
Three hospitals had just below 200 patients in all other surveys, but just above 200 patients in this survey.
35 12 11 6 7 71 4.1 (0–16.7) 5.7 (2.7–11.9) 5.6 (2.7–9.9) 5.6 (2.5–10.0) 5.7 (3.5–7.1) 5.4 (0–16.7) 32 12 12 5 7 68 (0–14.7) (1.6–9.5) (1.9–8.4) (3.1–7.0) (4.5–6.8) (0–14.7) 5.9 4.7 5.6 5.3 5.4 5.4 4.2 (0–16.7) 4.4 (0.9–8.7) 4.5 (0.9–7.4) 6.2 (3.5–8.0) 5.7 (3.5–9.2) 5.3 (0–16.7) 0–99 100–199 200–299 300–399 More than 400 Total prevalence
32 12 12 4 7 67
No. of hospitals Prevalence (range) in October 2003 (%) No. of hospitals Prevalence (range) in June 2003 (%) No. of hospitals Prevalence (range) in October 2002 (%) No. of hospitals Prevalence (range) in June 2002 (%) Groups of hospitals by number of patients
Table III
Average (range) prevalence of nosocomial infections by size (number of patients on the day of survey) in hospitals in Norway, 2002 and 2003
Prevalence of nosocomial infections in Norway
43 However, changes in the patient case mix and shortening of hospital stays may also have contributed to the change in trends. Also, the survey method changed slightly during the period. Prevalence seemed to plateau in 2002 and 2003. A potential weakness of our surveillance system is that several people are involved in registration. We have not held national training courses to ensure similar understanding of the survey protocol, and definitions of the nosocomial infections. However, all the infection control nurses were trained at the NIPH in surveillance methodology. Also, in most hospitals, infection control nurses hold a training session, and are available on the day of the survey to help interpret the definitions of infections. In addition, the same set of definitions and case finding methods were used by all institutions in our study. Gastmeier et al. showed that despite the use of very specific CDC criteria, there could still be subjectivity in the diagnosis of nosocomial infections. They suggested that even the use of less specific criteria than those of the CDC, or if the investigators are less qualified or well trained, could result in the investigator effect being even more marked.11 If, and to what degree, our modified definitions are less specific than the originals, is not known, but the main features of the CDC case definitions are included. The investigator effect is not known. Thus, the CDC case definitions subdivide surgical site infections into three categories. In our modified version, although only superficial and deep surgical site infections are recorded, the definition of deep surgical site infections includes both deep infections and infections in organs and spaces. The main advantage of our surveys is the high response rate. This excludes one major potential source of bias in the results. We believe that this high response rate was made possible through the quality of the instructions and the limited number of data elements to be recorded for each patient. A wide range of prevalence was reported from the different hospitals (0–16.7%). The widest range was found within institutions with less than 100 patients. Prevalence surveys thus seem most suitable for larger institutions. All patients were registered in the department in which they were resident on the day of the survey, irrespective of patient transfer since onset of infection. We made no attempt to assign infected patients retrospectively to the ward, department or hospital where the infections were most probably acquired. Such a procedure would have added complexity and potential for bias to the system. Thus, some departments or hospitals that receive
Number of nosocomial infections by type of infection and speciality in hospitals in Norway, June 2003
Department typea
Number of patients
Number of operations
Number of UTIs
Number of LRTIs
Number of superficial SSIs
Number of deep SSIs
Number of septicaemias
1973 172 100 175 204 659 232 359 206 468 1068 43 622 236 1224 100 320 75 4 126
116 6 3 2 23 34 22 11 8 60 529 14 252 126 800 66 151 50 4 53 62 19 133 89 147 107 62 13 34 4 93 54 41 82 1
44 5 0 3 12 12 2 3 8 11 22 0 9 7 40 1 10 2 0 2 5 1 0 1 1 1 1 1 16 3 17 9 0 0 5
36 1 4 0 8 13 4 10 2 7 12 0 8 5 12 1 0 0 0 4 16 11 14 1 0 0 2 0 6 1 4 2 0 4 0
3 1 0 0 0 1 1 4 0 2 7 0 4 5 12 0 2 1 0 0 2 0 0 1 1 4 2 1 1 0 1 3 0 1 0
12 1 0 1 2 1 6 1 0 3 15 0 14 4 42 1 0 1 0 0 5 2 5 0 2 0 4 0 4 0 1 0 0 0 0
6 1 0 2 1 1 3 0 3 1 1 0 2 1 3 0 1 0 0 0 5 1 4 0 2 1 7 7 0 1 0 0 0 0 0
3271
254
188
60
127
60
187 167 408 278 752 473 176 348 62 434 294 86 187 399 12 747
CI, confidence interval; UTI, urinary tract infection; LRTI, lower respiratory tract infection; SSI, surgical site infection; ENT, ear, nose and throat. a Hospitals that did not provide results by speciality are included in the total prevalence.
Total prevalence (%) (95% CI) 5.1 8.7 4.0 3.4 11.3 4.2 6.9 5.0 6.3 5.1 5.3 5.9 9.3 8.9 3.0 4.0 5.3 4.8 25.4 8.0 13.8 0.7 2.2 0.8 3.4 5.1 7.6 8.1 5.3 4.8 2.7 1.3
(4.1–6.1) (4.5–12.9) (0.2–7.8) (0.7–6.1) (6.9–15.6) (2.7–5.8) (3.6–10.1) (2.8–7.3) (3.0–9.6) (3.1–7.1) (4.0–6.7) – (4.1–7.8) (5.6–13.0) (7.3–10.5) (0.0–6.3) (1.9–6.2) (0.3–10.4) – (1.0–8.5) (17.9–32.9) (4.1–11.9) (8.6–19.0) (0.0–1.6) (0.5–3.9) (0.2–1.4) (1.8–5.0) (1.9–8.4) (5.0–10.6) (1.3–14.8) (3.2–7.4) (2.3–7.2) – (0.4–5.0) (0.2–2.3)
5.4 (5.0–5.8)
H.M. Eriksen et al.
General medicine Haematology Endocrinology Gastroenterology Geriatric Cardiovascular diseases Infectious diseases Pulmonary diseases Nephrology Oncology General surgery Paediatric surgery Gastroenterological surgery Cardiovascular surgery Orthopaedic surgery Thoracic surgery Urology Plastic surgery Maxillofacial surgery Neurosurgery Intensive medicine Medical intensive care Surgical intensive care Gynaecology/obstetric Gynaecology Newborn ward General paediatrics Neonatal ward Neurology Skin diseases Rehabilitation Rheumatology Ophthalmology ENT ward Psychiatry Totala
44
Table IV
Prevalence of nosocomial infections in Norway infected patients may feel that their rates are distorted. We explain this caveat when we present the data. Health authorities used the results from the June 2003 survey to rank hospital quality and for interhospital comparison. This may be misleading due to factors such as differences in case mix between hospitals and transfers of infected patients, which are not adjusted in these surveys. Many hospitals felt that they were wrongly designated as a hospital with an infection problem. This may be why fewer hospitals participated in the following survey. We argue that results from prevalence surveys are useful to gain an overview of the distribution and magnitude of nosocomial infections, but that the results must be compared with caution. If ranking hospitals by infection and control measures, results from incidence surveillance or indicators such as ratio of infection control personnel:patient beds and implementation of infection control programmes might give a more accurate picture than using results from prevalence surveys. We found prevalence surveys to be an acceptable, cheap and easy way of assessing nosocomial infection rates in Norwegian hospitals. Nurses and physicians reported that an additional benefit of the surveys involved staff education and awareness of the local problem with nosocomial infections. The surveys have been a contributing factor to implementing infection control measures such as infection control programmes and incidence surveillance systems. The data have also been used for political and administrative purposes, and as an argument for more resources for infection control in hospitals. The Government’s recent ‘Plan of action to prevent nosocomial infections 2004–2006’ made extensive use of the results from the prevalence surveys.
45
Acknowledgements We thank all the physicians and nurses who contributed to these surveys.
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