Improving Prediction of Surgical Site Infection Risk with Multilevel ModelingReportar como inadecuado

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Surgical site infection SSI surveillance is a key factor in the elaboration of strategies to reduce SSI occurrence and in providing surgeons with appropriate data feedback risk indicators, clinical prediction rule.


To improve the predictive performance of an individual-based SSI risk model by considering a multilevel hierarchical structure.

Patients and Methods

Data were collected anonymously by the French SSI active surveillance system in 2011. An SSI diagnosis was made by the surgical teams and infection control practitioners following standardized criteria. A random 20% sample comprising 151 hospitals, 502 wards and 62280 patients was used. Three-level patient, ward, hospital hierarchical logistic regression models were initially performed. Parameters were estimated using the simulation-based Markov Chain Monte Carlo procedure.


A total of 623 SSI were diagnosed 1%. The hospital level was discarded from the analysis as it did not contribute to variability of SSI occurrence p  = 0.32. Established individual risk factors patient history, surgical procedure and hospitalization characteristics were identified. A significant heterogeneity in SSI occurrence between wards was found median odds ratio MOR 3.59, 95% credibility interval CI 3.03 to 4.33 after adjusting for patient-level variables. The effects of the follow-up duration varied between wards p<10−9, with an increased heterogeneity when follow-up was <15 days MOR 6.92, 95% CI 5.31 to 9.07. The final two-level model significantly improved the discriminative accuracy compared to the single level reference model p<10−9, with an area under the ROC curve of 0.84.


This study sheds new light on the respective contribution of patient-, ward- and hospital-levels to SSI occurrence and demonstrates the significant impact of the ward level over and above risk factors present at patient level i.e., independently from patient case-mix.

Autor: Lauren Saunders, Marion Perennec-Olivier, Pascal Jarno, François L’Hériteau, Anne-Gaëlle Venier, Loïc Simon, Marine Giard,



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