Adherence to antihypertensive therapy prior to the first presentation of stroke in hypertensive adults: population-based study

Antihypertensive drug therapy is a major strategy of stroke prevention among hypertensive patients. The aim of this study was to estimate the excess risk of stroke associated with non-adherence to antihypertensive drug therapy among hypertensive patients. We conducted a population-based study using records from Finnish national registers for 1 January 1995 to 31 December 2007. Of the 73 527 hypertensive patients aged 30 years or older and without pre-existing stroke or cardiovascular disease, 2144 died from stroke and 24 560 were hospitalized due to stroke during the follow-up. At the 2- and 10-year follow-up after the start of continuous antihypertensive medication, non-adherent patients had 3.81 [95 confidence interval (CI) 2.855.10] and 3.01 (95 CI: 2.373.83) times higher odds of stroke death when compared with the adherent patients. The corresponding odds ratio (OR) for stroke hospitalization was 2.74 (95 CI: 2.353.20) at Year 2 and 1.71 (95 CI: 1.491.96) at Year 10. In the stroke-event year, the ORs were higher, 5.68 (95 CI: 5.056.39) for stroke death and 1.87 (95 CI: 1.722.03) for hospitalization. Among those using agents acting on the reninangiotensin system combined with diuretics or -blockers, these ORs were 7.49 (95 CI: 5.629.98) and 3.91 (95 CI: 3.234.75), respectively. The associations between non-adherence and stroke followed a doseresponse patternuthe poorer the adherence, the greater the risk of death and hospitalization due to stroke. These data suggest that poor adherence to antihypertensive therapy substantially increases near- and long-term risk of stroke among hypertensive patients.