REVIEWThe preventable proportion of nosocomial infections: an overview of published reports
Introduction
For the last 30 years, there has been great interest in understanding the causes and impact of hospital-acquired infections.1 Many experimental studies and randomized trials have examined various methods to prevent nosocomial infections.2., 3., 4., 5. Uncertainty remains, however, about the proportion of nosocomial infections that could potentially be prevented by infection control measures applied under routine working conditions.
Most estimates about the proportion of potentially preventable nosocomial infections were collected almost three decades ago during the SENIC study, which was performed between 1971 and 1976 and published 10 years later.6 This interventional cohort study showed that about 6% of all nosocomial infections could be prevented by minimal infection control efforts, and that 32% of all nosocomial infections could be prevented by well-organized and highly effective infection control programmes.6
It remains unclear whether these frequently mentioned results are still applicable today,7 as no other systematic, nationwide cohort study has attempted to replicate these findings. However, several large-scale prevalence studies have suggested that great potential may exist to reduce the prevalence of nosocomial infections on a regional or national scale.8., 9., 10., 11., 12., 13. Moreover, a number of single-centre intervention studies published during the last decade compared infection rates during two consecutive observation periods before and after implementation of multi-modal intervention measures (hereafter called intervention studies) and demonstrated the impact of standardized infection control policies and procedures under real-life conditions.14., 15.
Due to advanced molecular biology and typing methods, it is possible to identify cross-transmission between patients and to distinguish endogenous from exogenous nosocomial infections. Transmission studies may enable conclusions to be drawn about the potential preventability of exogenous nosocomial infections by avoiding cross-transmission.
The aim of this paper was to conduct a systematic review of the published literature to describe multi-modal intervention studies and transmission studies performed during the last decade, in order to give a crude estimate of the proportion of potentially preventable nosocomial infections under current healthcare conditions.
Section snippets
Methods
To identify intervention studies, we performed a MEDLINE search using combinations of the index terms ‘nosocomial, hospital, infection, intervention, incidence, survey and reduction’ for the period between January 1990 and October 2002. The search for intervention studies focussed on studies applying a multi-modal prevention strategy under real-life working conditions. To search for transmission studies the index terms ‘cross infection’ or ‘transmission’ or ‘typing’ were used. We excluded
Results
We identified 25 relevant intervention studies, which were performed in different parts of the world. The settings and patient populations were extremely diverse, offering a sample of the multi-farious nature of current medical care. Ten of the included studies investigated the influence of multi-modal interventions on all types of nosocomial infections (Table I),11., 14., 32., 33., 34., 35., 36., 37., 38., 39. whereas 15 studies focused on specific types of nosocomial infections (Table II).15.
Discussion
By definition, any infection not present or incubating at the time of admission to the hospital is classified as a nosocomial infection.58 To date, it remains unclear to what extent these nosocomial infections are avoidable under real-life hospital conditions and what represents the irreducible minimum.59 The simplest way to answer this question is to document infection rates before and after a multi-modal quality improvement intervention, adopting standardized policies, and if necessary,
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