Measuring Baseline Health with Individual Health-Adjusted Life Expectancy (iHALE)

ObjectivesAt any point of time, a persons baseline health is the number of healthy life years they are expected to experience during the course of their lifetime. In this article we propose an equity-relevant health metric, illness-specific individual Health Adjusted Life Expectancy (iHALE), that facilitates comparison of baseline health for individuals at the onset of different medical conditions, and allows for the assessment of which patient groups are worse off. A method for calculating iHALE is presented, and we use this method to rank four conditions in six countries according to several criteria of "worse off" as a proof of concept. MethodsiHALE measures baseline health at an individual level for specific conditions, and consists of two components: past health (before disease onset) and future expected health (after disease onset). Four conditions (acute myeloid leukemia (AML), acute lymphoid leukemia (ALL), schizophrenia, and epilepsy) are analysed in six countries (Ethiopia, Haiti, China, Mexico, United States and Japan). Data for all countries and for all diseases in 2017 were obtained from the Global Burden of Disease Study database. In order to assess who are the worse off, we focus on four measures: the proportion of affected individuals who are expected to attain less than 20 healthy life years (T20), the 25th and 75th percentiles of healthy life years for affected individuals (Q1 and Q3, respectively), and the average iHALE across all affected individuals. ResultsEven in settings where average iHALE is similar for two conditions, other measures may vary. One example is AML (average iHALE=58.7, T20=2.1, Q3-Q1=15.3) and ALL (57.7, T20=4.7, Q3-Q1=21.8) in the US. Many illnesses, such as epilepsy, are associated with higher baseline health in high-income settings (average iHALE in Japan=64.3) than in low-income settings (average iHALE in Ethiopia=36.8). ConclusioniHALE allows for the estimation of the distribution of baseline health of all individuals in a population. Hence, baseline health can be incorporated as an equity consideration in setting priorities for health interventions.