Infection Control Program, University of Geneva Hospitals and Faculty of Medicine, Geneva, Switzerland.
J Hosp Infect. 2011 Jun;78(2):86-91. doi: 10.1016/j.jhin.2011.02.003. Epub 2011 Apr 9.
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.
目前关于医院感染相关的住院时间过长（LOS）的证据受到方法学的限制，包括时间依赖性偏倚。为了确定与医院耐甲氧西林金黄色葡萄球菌（MRSA）感染和定植相关的 LOS 过长，在多状态模型中纳入了 797 例 MRSA 定植、167 例 MRSA 感染和 13640 例 MRSA 阴性的手术患者。MRSA 感染或定植的发生是时间依赖性暴露，出院或死亡是研究终点。通过计算转移概率矩阵的 Aalen-Johansen 估计量来提取 LOS 过长。使用多变量 Cox 回归分析评估 MRSA 对 LOS 过长的独立影响。与未感染患者相比，MRSA 感染使 LOS 延长了 14.5 天（95%置信区间：7.8，21.3），与仅定植 MRSA 的患者相比延长了 5.9 天（95%置信区间：0.1，11.7）。与无 MRSA 患者和 MRSA 携带者相比，医院获得性 MRSA 感染降低了出院的风险[校正危险比（HR）：0.69；95%置信区间：0.59，0.81；和 HR：0.79；95%置信区间：0.65，0.95]。在校正混杂因素后，MRSA 定植本身并不能降低出院的风险（HR：1.00；95%置信区间：0.93，1.07）。多状态模型是评估医院获得性抗生素耐药感染的健康经济学影响的一种很有前途的统计方法。
