Factors influencing survival following surgical treatment of obesity

The prevalence of obesity in the United States and the surgical treatment of obesity have increased since 1999. An important measure of outcome following surgical treatment is survival.

This study began with data prospectively collected from Jan 1, 1986 to Dec 31, 1999 by 55 data collection sites, representing 77 surgeons who used standardized data collection software developed by the International Bariatric Surgery Registry (IBSR). A subset of 18,972 subjects was submitted to the National Death Index (NDI) for search of death occurring from Jan 1, 1986 to Dec 31, 2001. The univariate survival analysis included Kaplan-Meier plots and log-rank tests. Cox proportional-hazards (PH) frailty model was used to identify risk factors and estimate hazard ratios in a multi-factor survival analysis. Covariates included gender, operative age, body mass index, operation category (simple and complex), operation year, diabetes, smoking and hypertension as recorded prior to operation.

Deaths were found for 3.45% of the patients (654/18,972). Average follow-up was 8.3 years. Age, gender, BMI, history of smoking, diabetes, and hypertension were significant predictors of survival. Operation category (P=0.13) and operation year (P=0.89) were not significant predictors of survival.

Simple and complex operations were equally effective in keeping patients alive in this cohort of patients operated on for severe obesity from 1986 to 1999. Young, female, non-smoking patients with low BMI at operation and no history of diabetes or hypertension had the longest survival. Longer follow-up for death is needed before any recommendations can be made for operation category based on survival.