Association between adherence to antihypertensive medications and health outcomes in middle and older aged community dwelling adults; results from the Irish longitudinal study on ageing.

Objective: To examine the association between antihypertensive medication (AHTM) implementation adherence and healthcare utilisation in community-dwelling adults aged ≥ 50 years in Ireland.

Methods: This was a prospective cohort study. The Irish Longitudinal Study on Ageing (TILDA) was linked to pharmacy claims data for participants aged ≥ 50 years. Participants were included if they had ≥ 3 pharmacy claims for one or more AHTM (ATC codes 'C02', 'C03', 'C07', 'C08' or 'C09') within the year preceding the year of self-reported healthcare utilisation outcome occurrence. Outcomes included self-reported general practitioner (GP), emergency department (ED), outpatient department visits and hospital admissions. Implementation adherence was measured using proportion of days covered (PDC), with participants classified as adherent if the average PDC ≥ 0.8. Negative binomial models were used to analyse the association between AHTM adherence and number of GP, ED, outpatient visits and hospitalisations (adjusted IRR and 95% CI are presented).

Results: One thousand four hundred thirty-one participants were included. The majority of participants (72.6%) were considered adherent. Good implementation adherence to AHTM was associated with a significant decrease in self-reported GP visits (adjusted IRR 0.91, 95% CI 0.83-0.99). Adherence had no significant impact on the number of ED visits, outpatient visits or hospitalisations reported by TILDA participants.

Conclusions: Good adherence to AHTM was associated with less self-reported GP visits in this population, suggesting improved overall health status. However, the impact of medication non-adherence on the other self-reported healthcare utilisation outcomes (ED, outpatient visits and hospitalisations) was not evident in this study.