Demographic Change and Drug Expenditure Growth in the National Health Insurance: a Decomposition Analysis

Abstract

This study quantified the relative and absolute importance of different factors contributing to changes in drug expenditures in the Korean National Health Insurance from 2009 to 2013. We decomposed changes in drug spending into five components: patient population size, population ageing, number of prescriptions per patient, duration of medication per prescription, medication intensity(cost per medication day). Drug expenditure increased by 9.84% from 2009 to 2013. Patient population size, population ageing and duration of medication contributed to increase of drug expenditure for the whole period of 2009~2013. Demographic factors including patient population size and population ageing caused the growth of drug expenditures by 7.04% from 2009 to 2013, accounting for 71.6% of the change of drug spending of that period. Duration of medication was the most contributing factor to the growth of drug spending, accounting for 150.9% of the increase of drug spending during 2009~2013. Medication intensity, which highly correlate with drug price, contributed to lowering drug expenditure. In 2009~2013, medication intensity dropped drug spending by 11.9%, although substantial amount of the growth was offset by other factors. This is the first study which estimated the contribution of demographic changes in the change of drug expenditures in the National Health Insurance in Korea. We found that the contribution of population ageing to the increase of drug spending has risen in the study period. It implies that the impact of the change of age structure on drug expenditure growth will increase in the future with population ageing.