Drug adherence in treatment resistant and in controlled hypertension—Results from the Swedish Primary Care Cardiovascular Database (SPCCD)

PURPOSE: To assess drug adherence in patients treated with ≥3 antihypertensive drug classes, with both controlled and uncontrolled blood pressure and describe associated factors for nonadherence. METHODS: Patients with hypertension, without cardiovascular comorbidity, aged >30 years treated with ≥3 antihypertensive drug classes were followed for 2 years. Both patients with treatment resistant hypertension (TRH) and patients with controlled hypertension were included. Clinical data were derived from a primary care database. Pharmacy refill data from the Swedish Prescribed drug registry was used to calculate proportion of days covered (PDC). Patients with a PDC level ≥ 80% were included. RESULTS: We found 5846 patients treated ≥3 antihypertensive drug classes, 3508 with TRH (blood pressure ≥ 140/90), and 2338 with controlled blood pressure (<140/90 mm Hg). TRH patients were older (69.1 vs 65.8 years, P < .0001) but had less diabetes (28.5 vs 31.7%, P < .009) compared with patients with controlled blood pressure. The proportion of patients with PDC ≥ 80% declined with 11% during the first year in both groups. Having diabetes was associated with staying adherent at 1 year (RR 0.82; 95% CI, 0.68-0.98) whilst being born outside Europe was associated with nonadherence at one and (RR 2.05; 95% CI, 1.49-2.82). CONCLUSIONS: Patients with multiple antihypertensive drug therapy had similar decline in adherence over time regardless of initial blood pressure control. Diabetes was associated with better adherence, which may imply that the structured caregiving of these patients enhances antihypertensive drug treatment.