Trends in years lost due to disability: changes due to prevalence or severity? The case of Germany

Abstract Background The indicator years lost due to disability (YLD) is one of the two main components of the summary measure of population health: disability-adjusted life year (DALY). It quantifies the health gap between a population in perfect health and actual health status due to morbidity. The YLD is used not only to measure the years spent with health impairments, but also to monitor population health, set priorities and evaluate new health programs. Methods YLD are calculated by using information on disease frequencies split by levels of severities (severity distributions, SD) or related health states. The time spent with disease is converted into YLD by weighting each year with health limitations using disability weights. We used claims data from the largest statutory health insurance company in Germany (AOK) and we estimated prevalence, SD and YLD for the period 2017 to 2022 according to sex, age and region. Results We assessed prevalence and SD for four types of cancers, hypertensive heart disease, diabetes and depressive disorders. We observed time developments not only in the prevalence but also in the SD for each disease. For instance, in diabetes, except for the prevalence increase over time, we found increase in diabetic foot and decrease in diabetic neuropathy. As these health states are differently weighted, they contribute differently to the total YLD. Thus, changes in YLD are not only driven from prevalence but also from the dynamics in the health states. Conclusions The observed time trends in YLD reflect the complex relationship between all input components and the valuable information they provide. As SDs are highly dependent not only on utilization at the individual level, but also on available health care services at the society level, they can be used to highlight needs for prevention. Furthermore, changes in the share of severe cases over time, may reflect the effectiveness of health interventions and policies. Key messages • Changes in YLD incorporate changes in frequency or severity. Thus, it is crucial to disentangle the components of the measure in order to obtain valuable information for potential health care measures. • The progression of many of the sequelae can be avoided through (secondary) preventive measures. Therefore, the severity level is an important indicator of the population affected and in need for care.