Mendelian Randomization analysis of the causal effect of adiposity on hospital costs

Publication date: Available online 25 January 2020Source: Journal of Health EconomicsAuthor(s): Padraig Dixon, William Hollingworth, Sean Harrison, Neil M. Davies, George Davey SmithAbstractEstimates of the marginal effect of measures of adiposity such as body mass index (BMI) on healthcare costs are important for the formulation and evaluation of policies targeting adverse weight profiles. Most estimates of this association are affected by endogeneity bias. We use a novel identification strategy exploiting Mendelian Randomization – random germline genetic variation modelled using instrumental variables – to identify the causal effect of BMI on inpatient hospital costs. Using data on over 300,000 individuals, the effect size per person per marginal unit of BMI per year varied according to specification, including £21.22 (95% confidence interval (CI): £14.35-£28.07) for conventional inverse variance weighted models to £18.85 (95% CI: £9.05-£28.65) for penalized weighted median models. Effect sizes from Mendelian Randomization models were larger in most cases than non-instrumental variable multivariable adjusted estimates (£13.47, 95% CI: £12.51-£14.43). There was little evidence of non-linearity. Within-family estimates, intended to address dynastic biases, were imprecise.

Source: Journal of Health Economics - January 26, 2020 Category: Health Management Source Type: research