Background
The incidence of obesity and the need for subsequent weight loss surgery in Australia is on the rise. The National Health Survey revealed that from 2014-2015, 63.4% of Australian adults were overweight or obese, an increase from 56.3% in 1995. Excess body weight can be a risk factor for developing chronic diseases such as cardiovascular disease, diabetes and kidney disease. It is therefore vital to understand the safety and outcomes of bariatric surgery and identify the risks associated with further weight gain that requires revision surgery.
Aim
This research project aimed to investigate several modelling approaches to identify key baseline factors associated with revision incidence and the time between primary and revision surgeries.
Methods
Data extracted from the Bariatric Surgery Registry on 13 February 2018 was used to analyse primary bariatric patients with procedures performed in Australian hospitals from February 2012 to December 2016. Nelson-Aalen cumulative revision incidence rates were calculated and the Cox proportional hazards model was used to identify individual demographic and clinical variables associated with revision. A stepwise regression model process and Likelihood ratio tests were used to identify the final multivariate specification. Time varying covariates and stratification methods were explored.
Results
A total of 14,150 primary bariatric patients met the inclusion criteria with 1.9% of patients having revision surgery within 12 months of their primary surgery. After stratification by primary procedure type and the year of primary surgery, male patients and primary surgery in private hospitals were protective factors for revision incidence.