Long-term cost-effectiveness of interventions for obesity: A mendelian randomisation study

• Published in: PLoS medicine 2021-08, Vol.18 (8), p.e1003725-e1003725
• Main Authors: Harrison, Sean, Dixon, Padraig, Jones, Hayley E, Davies, Alisha R, Howe, Laura D, Davies, Neil M
• Format: Article
• Language: English
• Subjects: Adult; Aged; Bias; Biobanks; Biology and Life Sciences; Body Mass Index; Cardiovascular disease; Cardiovascular diseases; Care and treatment; Cerebrovascular diseases; Cost analysis; Cost benefit analysis; Diabetes mellitus (non-insulin dependent); Epidemiologic methods; Estimates; Female; Gastrointestinal surgery; Genetic aspects; Genome-wide association studies; Genomes; Genotypes; Health care; Health Care Costs - statistics & numerical data; Health risk assessment; Humans; Intervention; Laparoscopy; Male; Medicine and Health Sciences; Mendelian Randomization Analysis; Methods; Middle Aged; Obesity; Obesity - economics; Obesity - prevention & control; People and places; Pleiotropy; Primary care; Primary Health Care - economics; Quality of life; Quality-Adjusted Life Years; Secondary Care - economics; Simulation; Social Sciences; Surgery
• ISSN: 1549-1676; 1549-1277; 1549-1676
• DOI: 10.1371/journal.pmed.1003725

The prevalence of obesity has increased in the United Kingdom, and reliably measuring the impact on quality of life and the total healthcare cost from obesity is key to informing the cost-effectiveness of interventions that target obesity, and determining healthcare funding. Current methods for estimating cost-effectiveness of interventions for obesity may be subject to confounding and reverse causation. The aim of this study is to apply a new approach using mendelian randomisation for estimating the cost-effectiveness of interventions that target body mass index (BMI), which may be less affected by confounding and reverse causation than previous approaches. We estimated health-related quality-adjusted life years (QALYs) and both primary and secondary healthcare costs for 310,913 men and women of white British ancestry aged between 39 and 72 years in UK Biobank between recruitment (2006 to 2010) and 31 March 2017. We then estimated the causal effect of differences in BMI on QALYs and total healthcare costs using mendelian randomisation. For this, we used instrumental variable regression with a polygenic risk score (PRS) for BMI, derived using a genome-wide association study (GWAS) of BMI, with age, sex, recruitment centre, and 40 genetic principal components as covariables to estimate the effect of a unit increase in BMI on QALYs and total healthcare costs. Finally, we used simulations to estimate the likely effect on BMI of policy relevant interventions for BMI, then used the mendelian randomisation estimates to estimate the cost-effectiveness of these interventions. A unit increase in BMI decreased QALYs by 0.65% of a QALY (95% confidence interval [CI]: 0.49% to 0.81%) per year and increased annual total healthcare costs by £42.23 (95% CI: £32.95 to £51.51) per person. When considering only health conditions usually considered in previous cost-effectiveness modelling studies (cancer, cardiovascular disease, cerebrovascular disease, and type 2 diabetes), we estimated that a unit increase in BMI decreased QALYs by only 0.16% of a QALY (95% CI: 0.10% to 0.22%) per year. We estimated that both laparoscopic bariatric surgery among individuals with BMI greater than 35 kg/m2, and restricting volume promotions for high fat, salt, and sugar products, would increase QALYs and decrease total healthcare costs, with net monetary benefits (at £20,000 per QALY) of £13,936 (95% CI: £8,112 to £20,658) per person over 20 years, and £546 million (95% CI: £435 million to £6