Prolonged duration of operation: an indicator of complicated surgery or of surgical (mis)management?

PURPOSE: The aim of this study was to investigate whether a prolonged operative time should be regarded as an indicator of quality problems in operating rooms or as patient-specific risk factors when analyzing surgical site infection (SSI) rates.
METHOD: Data from the SSI component of the German national nosocomial infection surveillance system (KISS) were used to address this question. Eight procedure categories tracked by at least 30 departments participating in KISS were included in the analysis, namely, hip (2 types) and knee prosthesis, breast surgery, hernia repair, C-section, cholecystectomy and colon operations. Various multiple logistic regression analyses were performed for each procedure category to predict duration of operation. Patient factors (sex, age, American Society of Anesthesiologists score, wound contamination class) and hospital factors (hospital status, size, annual volume) were considered. The area under the receiver operating characteristic (ROC) curve was used to evaluate predictive power including patient- and hospital-based factors.
RESULTS: A total of 253,454 operations were included in the analysis. In general, the predictive power of the model including all variables for the different procedure types was relatively low (C-index range: 0.57-0.63) and not much higher than that of the models including only patient-based or only hospital-based variables, respectively. The predictive power for the duration of operative time based on the model including only hospital-based variables was as good as or better than that of the model including only patient-based factors.
CONCLUSION: Duration of operation is at least partially determined by hospital factors and, consequently, should be used as a quality indicator to compare SSI infections between hospitals, rather than being used as a patient factor to adjust comparisons between hospitals.