Socio-demographic and genetic risk factors for drug adherence and persistence: a retrospective nation-wide and biobank study across 5 medication classes and 1 814 521 individuals

Low drug adherence is a major obstacle to the benefits of pharmacotherapies and it is therefore important to identify factors associated with discontinuing or being poorly adherent to a prescribed treatment regimen. Using high-quality nationwide health registry data and genome-wide genotyping, we evaluate the impact of socio-demographic and genetic risk factors on adherence and persistence for 5 common medication classes that require long-term, regular therapy (N = 1 814 591 individuals from Finnish nationwide registries, 217 005 with genetic data from Finland and Estonia). Need for social assistance and immigration status showed a notable negative effect on persistence and adherence across the examined medications (odd ratios between 0.48 and 0.82 for persistence and between 1.1% to 4.3% decrease in adherence) while demographic and health factors showed comparably modest or inconsistent effects. A genome-wide scan did not identify genetic variants associated with the two phenotypes, while some pharmacogenes (i.e. CYP2C9 and SLCO1B1) were modestly associated with persistence, but not with adherence. We observed significant genetic correlations between medication adherence and participation in research studies. Overall, our findings suggest that socio-economically disadvantaged groups would benefit from targeted interventions to improve the dispensing and uptake of pharmacological treatments.