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Title: Herd peril within studies of decontamination in the ICU context? An umbrella review of >200 Ventilator-associated Pneumonia (VAP) prevention studies.
Author: Hurley, James C.
Issue Date: 2019
Conference Name: Ballarat Health Services 2019 Annual Research Symposium
Conference Date: 28 November
Conference Place: Ballarat
Abstract: Background Topical antibiotics appear superior at preventing VAP and mortality among ICU patients than other methods. Objectives/Aims To test the postulate that concurrent control (CC) patients within ICU’s studying topical oropharyngeal antibiotics to prevent VAP and mortality would experience spill-over effects. Method Data sources: Studies of various topical antibiotic and other infection prevention interventions among ICU patients were obtained by snowball sampling. Study selection: Studies of topical antibiotics, stratified into CC versus non-concurrent control (NCC) designs. Studies of non-antibiotic based infection prevention interventions provide additional points of reference. Studies with no infection prevention intervention provide the mortality benchmark. Data Extraction: Mortality proportion data, mortality census, study characteristics, group mean age, ICU type, and study publication year. Results 206 studies were examined. The summary effect sizes for VAP and mortality prevention derived in the 15 systematic reviews were replicated. The mean ICU mortality incidence for CC control groups of topical antibiotic studies (28.5%; 95% CI, 25.0-32.3; n = 41) is higher versus the benchmark (23.7%; 19.2%-28.5%; n = 34), versus NCC control groups (23.5%; 19.3-28.3; n = 14) and versus intervention groups (24.4%; 22.1 – 26.9; n=62) of topical antibiotic studies. In meta-regression models adjusted for group level characteristics such as group mean age and publication year, CC group membership within a topical antibiotic study remains associated with higher mortality (p = 0.027) whereas other group memberships, including membership within an anti-septic study, are each neutral (p = NS). Implications/Outcomes for Planned Research Project Within topical antibiotic studies, the CC control group mortality incidences are inexplicably high, whereas the intervention group incidences are paradoxically closer to a literature-derived benchmark. Unexplained VAP and mortality excess in the CC groups implicates spill-over effects within studies of topical antibiotics. The apparent VAP and mortality prevention effects may be spurious. Final Thoughts The plan is to use this dataset derived from the literature to investigate the concept of ICU dysbiosis. This is where changing the ICU microbiome (as reflected in the VAP isolates) changes the risk of invasive infections (as reflected in bacteremia isolates). Synergy between Candida colonization and invasive bacterial infections (Staphylococcus and Pseudomonas) has been postulated but otherwise difficult to study. The study methodology uses structural equation modelling, a technique with common use in ecological studies.
Internal ID Number: 01434
Type: Conference
Appears in Collections:Research Output

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