Change in body mass index and disease burden among people with obesity and multiple long-term conditions

Obesity is a risk factor for multiple long-term conditions (MLTCs/multimorbidity). However, the impact of weight loss in people with MLTCs is unclear. We investigated the association between body mass index (BMI) change and the development of obesity-related complications (ORCs), as well as clinical and economic outcomes in individuals with obesity and MLTCs.

This cohort study included adults aged ≤70 years with BMI ≥30 kg/m² and ≥2 ORCs. BMI was recorded during Years 1 and 4 of the baseline period. BMI change was categorised as increases or decreases of 3%-7%, 7%-15% and 15%-30%. Data were analysed using Cox regression (hazard ratios [HRs] for mental-health conditions, hospitalisation and mortality) and Ghosh-Lin models (risk of ≥1 new ORC and clinical consultations).

A total of 618 426 individuals were included. The mean number of ORCs at index (Year 4) was 3.8 (standard deviation 1.5). HRs (95% confidence intervals) for incident ORCs were 0.96 (0.94-0.98), 0.98 (0.96-0.99) and 0.98 (0.97-0.99) for the highest to lowest BMI reductions, respectively; BMI increases were associated with HRs >1.00. Risk ratios for consultations were 0.99 (0.98-1.00), 0.99 (0.98-1.00) and 1.00 (0.99-1.00). BMI reductions were linked to lower polypharmacy rates. Both BMI decrease and increase were associated with higher HRs for mental-health conditions, hospitalisation and mortality versus stable BMI.

Weight loss in individuals with obesity and MLTCs was linked to both favourable and adverse outcomes, highlighting the importance of personalised treatment approaches that consider outcomes beyond weight loss.