Introduction of laboratory based ward liaison surveillance of hospital infection into six district general hospitals.

A previous study demonstrated that laboratory based ward liaison surveillance (LBWLS) of hospital infection was an effective and efficient method. The method involved the follow-up of positive microbiology reports by the review of patient records and liaison with ward nursing staff to consider whether any patients had infection. Here we report the introduction of LBWLS into six district general hospitals to determine whether it is feasible to use this method on an everyday basis. The time required for data collection was assessed and the method was compared with a reference method in one hospital to check its ability to detect infections. To assess reproducibility two infection control nurses (ICNs) performed LBWLS independently, but concurrently, for 5 weeks. The method could be used in all hospitals studied; however, the time for data collection ranged from 3.0 to 6.8 h/100 beds per week. In comparison with the reference method, LBWLS detected 15/41 (37%) of community acquired infections and 30/43 (70%) of hospital acquired infections. In the reproducibility assessment 72 patients were identified by both ICNs. There was agreement about the infected/non-infected status of 65 of these patients. The mean pair agreement and Kappa statistic were 0.88 and 0.72. Laboratory based ward liaison was readily used in all hospitals and was reproducible.

How do we collect data for surveillance of wound infection?

The surveillance of surgical wound infection (SWI) may be undertaken for a number of purposes which include evaluating changes in practice, studying the epidemiology of SWI and for assessing the quality of health care. Purchasers require this information from providers as an indicator of the quality of care. Surveillance of SWI can also have a role in audit, by setting standards and comparing observed practice with agreed standards. The level of SWI can be the standard, and the collection, analysis and interpretation of data (undertaken during surveillance) could be the means for measuring the standard. In a surveillance programme, data collection is often the most time consuming and difficult element and requires considerable planning. Initially, the data to be collected should be defined. This will be influenced by the purposes of surveillance, the ways the events (SWI) are defined, the data required to produce meaningful analyses and criteria used for identifying the patient. After the data has been defined, data collection methods should be chosen. The importance of assessing the accuracy and limitations of data collection methods in local settings is stressed. Only then is it possible to be sure that the data is a reliable basis on which to base decisions which promote the quality of health care.

An evaluation of surveillance methods for detecting infections in hospital inpatients.

Eight selective surveillance methods were compared with a reference method for their ability to detect hospital infections in patients was also assessed. In the reference method, case records were reviewed three times a week, and during the 11-month period of study, 668 infections were identified amongst 3326 patients. Three hundred and thirty-eight were community acquired infections (CAI) and 330 were hospital acquired infections (HAI). The time for data collection was 18.1 h per 100 beds per week. Of the selective surveillance methods, those based on the review of treatment and temperature charts detected the highest proportion (70%) of CAI; and the review of microbiology reports with regular ward liaison identified the highest proportion (71%) of HAI. The time for data collection in the eight methods ranged from 1.2 h per 100 beds per week to 6.5 h per 100 beds per week. After considering the sensitivity for identifying patients with HAI and time for data collection, the review of microbiology reports with regular ward liaison was judged to be an effective and efficient method of surveillance.

Incidence of hospital-acquired infection and length of hospital stay.

Two different measures of hospital-acquired infection (HAI), risk per discharge and incidence rate, were used to analyse the incidence of 225 primary HAIs detected in 3,090 patients in an 11-month survey. Longer hospital stay was associated with a greater risk of developing HAI, but the strength of the association was different for the two measures used. Day-specific incidence rates were found to vary, with a peak between the 14th and 19th days of hospitalisation. Similar patterns were observed when the data were stratified by age, sex and operation. Methods for calculating HAI should control for the length of hospital stay. Further studies are required to clarify the mechanisms that affect the temporal pattern of incidence of HAI observed with length of hospitalisation.

An 11-month incidence study of infections in wards of a district general hospital.

Between March 1988 and January 1989, an incidence study of infections in patients occupying 122 beds in a district general hospital was undertaken. Nursing notes, medical notes, temperature charts, drug prescription charts and laboratory information were reviewed three times a week to determine if patients had infection which met strict case definitions. In addition, the surveyor consulted with ward nursing and medical staff for clarification of symptoms and signs indicative of infection. During the study, 668 infections were identified amongst 3326 patients. Three hundred and thirty-eight (51%) were community-acquired infections (CAI) and 330 hospital-acquired infections (HAI). Excluding 24 HAI acquired in other hospitals, the incidence rates were 9.2 HAI per 100 discharges, and 1.1 HAI per 100 patient days. The common types of CAI were pneumonia, abdominal infection and urinary tract infection. The main types of HAI were urinary tract infection, surgical wound infection and pneumonia. The microorganisms most frequently associated with CAI and HAI were Gram-negative bacilli.