Clinical characteristics of patients undergoing primary bariatric surgery in the United Kingdom based on the National Bariatric Surgery Registry.

Baseline demographic characteristics and operations undertaken for patients having bariatric surgery in the United Kingdom are largely unknown. This study aimed to describe the profile of patients having primary bariatric surgery in the National Health Service (NHS) or by self-pay, and associated operations performed for both pathways. The National Bariatric Surgery Registry dataset for 5 years between January 2015 and December 2019 was used. 34 580 patients underwent primary bariatric surgery, of which 75.9% were NHS patients. Mean patient age and initial body mass index were significantly higher for NHS compared to self-pay patients (mean age 45.8 ± 11.3 [SD] vs. 43.0 ± 12.0 years and initial body mass index 48.0 ± 7.9 vs. 42.9 ± 7.3 kg/m 2 , p < .001). NHS patients were more likely to have obesity-related complications compared to self-pay patients: prevalence of Type 2 diabetes mellitus 27.7% versus 8.3%, hypertension 37.1% versus 20.1%, obstructive sleep apnoea 27.4% versus 8.9%, severely impaired functional status 19.3% versus 13.9%, musculoskeletal pain 32.5% versus 20.1% and being on medication for depression 31.0% versus 25.9%, respectively (all p < .001). Gastric bypass was the most commonly performed primary NHS bariatric operation 57.2%, but sleeve gastrectomy predominated in self-pay patients 48.7% (both p < .001). In contrast to self-pay patients, NHS patients are receiving bariatric surgery only once they are older and at a much more advanced stage of obesity-related disease complications.