Harrison S, Dixon P, Jones HE, et al. - Mendelian randomization can be used to calculate the effect of interventions on quality of life and healthcare costs. The authors discovered that when accounting for 240 chronic health conditions, the effect of increasing body mass index (BMI) on health-related quality of life is much larger than when only a small selection is used. This means that previous cost-effectiveness studies likely underestimated the effect of BMI on quality of life and, as a result, the potential cost-effectiveness of BMI-reduction interventions.

• A total of 310,913 unrelated white British participants from England and Wales were included in the analysis.

• A unit increase in BMI reduced QALYs by 0.65% of a QALY per year and increased annual total healthcare costs by £42.23 per person.

• They estimated that a unit increase in BMI decreased QALYs by only 0.16% of a QALY per year when only health conditions commonly considered in the previous cost-effectiveness modelling studies (cancer, cardiovascular disease, cerebrovascular disease, and type 2 diabetes).

• Both laparoscopic bariatric surgery and restricting volume promotions for high fat, salt, and sugar products were estimated to increase QALYs and decrease total healthcare costs, with net monetary benefits (at £20,000 per QALY) of £13,936 per person over 20 years and £546 million total per year, respectively.