Pharmaceutical utilisation and costs before and after bariatric surgery

OBJECTIVE: To determine whether pharmaceutical utilisation and costs change after bariatric surgery. SUBJECTS: Total population of Australians receiving Medicare-subsidised laparoscopic adjustable gastric banding (LAGB) in 2007 (n= 9542). DESIGN: Computerised data linkage with Medicare, Australia's universal tax-funded health insurance scheme. Pharmaceuticals relating to obesity-related disease and postsurgical management were assigned to therapeutic categories and analysed. The mean annual numbers of pharmaceutical prescriptions for each category were compared over the 4-year period from the year before LAGB (2006) to 2 years after LAGB (2009) using utilisation incidence rate ratios (IRRs). RESULTS: The population was mainly female (77.7%) and age was normally distributed with the majority (60.7%) of subjects aged between 35-54 years. Utilisation rates decreased significantly after LAGB in the following therapeutic categories: diabetes (IRR 0.51, IRR 95% CI 0.50-0.53, mean annual cost differences per person $ 30), cardiovascular (0.81, 0.80-0.82, $ 29), psychiatric (0.95, 0.93-0.97, $ 13), rheumatic and inflammatory disorders (0.51, 0.49-0.53, $ 10) and asthma (0.78, 0.75-0.81, $ 9). In contrast, significantly greater utilisation was observed in the pain (1.28, 1.23-1.32, $ 12), gastrointestinal tract disorder (1.04, 1.02-1.07, $ 5) and anaemia/vitamins (2.34, 2.01-2.73, $ 4) therapeutic categories. When the defined categories were combined, a net reduction in pharmaceutical utilisation was observed, from 10.5 to 9.6 pharmaceuticals prescribed per person/year, and costs decreased from $ AUD517 to $ AUD435 per year in 2009 prices. CONCLUSION: Relative to the year before LAGB, overall pharmaceutical utilisation was reduced in the 2 years after the year of LAGB surgery, demonstrating that bariatric surgery can lead to reductions in pharmaceutical utilisation in the 'real world' setting. The greatest absolute cost reductions were observed in the therapies to treat diabetes and cardiovascular disease.