title: Multistate modelling to estimate the excess length of stay associated with meticillin-resistant Staphylococcus aureus colonisation and infection in surgical patients.
abstract: Currently available evidence on the excess length of stay (LOS) associated with nosocomial infections is limited by methodology, including time-dependent bias. To determine the excess LOS associated with nosocomial meticillin-resistant Staphylococcus aureus (MRSA) infection and colonisation, 797 MRSA-colonised, 167 MRSA-infected and 13,640 MRSA-negative surgical patients were included in a multistate model. The occurrence of MRSA infection or colonisation was the time-dependent exposure, and discharge or death was the study endpoint. The excess LOS was extracted by computing the Aalen-Johansen estimator of the matrix of transition probabilities. Multivariate Cox regression analysis was used to assess the independent effect of MRSA on excess LOS. MRSA infection prolonged LOS by 14.5 [95% confidence interval (CI): 7.8, 21.3] days compared to uninfected patients, and by 5.9 (95% CI: 0.1, 11.7) days compared to patients only colonised by MRSA. The hazard of discharge was reduced by nosocomial MRSA infection both with respect to MRSA-free patients and MRSA carriers [adjusted hazard ratio (HR): 0.69; 95% CI: 0.59, 0.81; and HR: 0.79; 95% CI: 0.65, 0.95, respectively]. MRSA carriage alone did not decrease the hazard of discharge after adjustment for confounding (HR: 1.00; 95% CI: 0.93, 1.07). Multistate modelling is a promising statistical method to evaluate the health-economic impact of nosocomial antibiotic-resistant infections.
authors.affiliation: Infection Control Program, University of Geneva Hospitals and Faculty of Medicine, Geneva, Switzerland.
authors.forename: G
authors.initials: G
authors.lastname: De Angelis
authors.forename: A
authors.initials: A
authors.lastname: Allignol
authors.forename: A
authors.initials: A
authors.lastname: Murthy
authors.forename: M
authors.initials: M
authors.lastname: Wolkewitz
authors.forename: J
authors.initials: J
authors.lastname: Beyersmann
authors.forename: E
authors.initials: E
authors.lastname: Safran
authors.forename: J
authors.initials: J
authors.lastname: Schrenzel
authors.forename: D
authors.initials: D
authors.lastname: Pittet
authors.forename: S
authors.initials: S
authors.lastname: Harbarth
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D002353:Carrier State / Q000188:drug therapy / Q000191:economics / Q000453:epidemiology* / Q000382:microbiology; D003428:Cross Infection / Q000188:drug therapy / Q000191:economics / Q000453:epidemiology* / Q000382:microbiology; D006801:Humans; D007902:Length of Stay / Q000191:economics / Q000706:statistics & numerical data*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification*; D008954:Models, Biological; D010351:Patient Discharge / Q000706:statistics & numerical data; D016016:Proportional Hazards Models; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000191:economics / Q000453:epidemiology / Q000382:microbiology; D013530:Surgical Wound Infection / Q000188:drug therapy / Q000191:economics / Q000453:epidemiology* / Q000382:microbiology; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents