A comparison of the World Health Organisation's HEAT model results using a non-linear physical activity dose response function with results from the existing tool

Abstract

IntroductionThe WHO-Europe’s Health Economic Assessment Tool is a tool used to estimatethe costs and benefits of changes in walking and cycling. Due to data limitationsthe tool’s physical activity module assumes a linear dose response relationship be-tween physical activity and mortality.MethodsThis study estimates baseline population physical activity distributions for 44 coun-tries included in the HEAT. It then compares, for three different scenarios, the re-sults generated by the current method, using a linear dose-response relationship,with results generated using a non-linear dose-response relationship.ResultsThe study finds that estimated deaths averted are relatively higher (lower) using thenon-linear effect in countries with less (more) active populations. This difference islargest for interventions which affect the activity levels of the least active the most.Since more active populations, e.g. in Eastern Europe, also tend to have lowerValue of a Statistical Life estimates the net monetary benefit estimated by the sce-narios are much higher in western-Europe than eastern-Europe.ConclusionsUsing a non-linear dose response function results in materially different estimateswhere populations are particularly inactive or particularly active. Estimating base-line distributions is possible with limited additional data requirements, although themethod has yet to be validated. Given the significant role of the physical activitymodule within the HEAT tool it is likely that in the evaluation of many interventionsthe monetary benefit estimates will be sensitive to the choice of the physical activitydose response function.