Health utility in preclinical and prodromal AD compared to controls: EQ5D data from the Swedish Biofinder Study

Abstract

Background Health utility values (e.g. as assessed with EuroQoL 5 domains, EQ5D) are central for the health economic evaluation of candidate treatments for Alzheimer's disease (AD). Currently available estimates in early stages of disease including preclinical and prodromal AD are limited, and do not separate patients by biomarker status. Method Baseline data from the longitudinal Swedish BioFINDER study on patients in different stages of AD and cognitively healthy controls were analyzed. Subjects were either cognitively unimpaired healthy elderly controls sampled from a population‐based cohort, or patients with cognitive complaints (subjective cognitive decline (SCD) or mild cognitive impairment (MCI)), but without dementia, referred to memory clinics. Health utility was assessed with EQ5D (3 level version) recalculated into a utility index with the UK tariff; higher scores representing higher utility. Cerebrospinal fluid amyloid biomarker positive subjects were defined as prodromal AD if they met criteria for MCI and otherwise defined as preclinical AD. Result Five‐hundred‐ninety‐nine non‐dementia subjects aged between 60 and 88 years were assessed at baseline. Individuals with SCD or MCI reported lower health utility (n=245, mean=0.78, 95% CI 0.75‐0.80) compared to cognitively healthy elderly controls (n=354, mean 0.90 95% CI 0.88‐0.91), regardless of biomarker status. Prodromal AD patients reported higher health utility (n=79, mean=0.81, 95% CI 0.77‐0.85) compared to amyloid‐negative MCI patients (n=54, mean=0.71, 95% CI 0.64‐0.77). Prodromal AD patients were less often smoking, fewer had prior ischemic heart disease and were less often treated with anti‐depressants, compared to amyloid‐negative MCI patients. Subjects with preclinical AD reported health utility (n=114, mean 0.86, 95% CI 0.83‐0.88) which were similar to amyloid‐negative cognitively unimpaired (i.e. SCD and controls) (n=305, mean=0.87, 95% CI 0.86‐0.89). Conclusion Health utility was lower in biomarker confirmed preclinical and prodromal AD patients compared to cognitively healthy controls. The analysis suggests that amyloid biomarker status is an important determinant of health utility in patients with MCI. This may be explained by more severe co‐morbidities in biomarker negative patients. In particular, the cause of their cognitive symptoms (e.g. cardiovascular disease) may be associated with a greater impact on their quality of life in early stages of disease.