Predictors of persistence with antihypertensive therapy: results from the NHANES.

BACKGROUND: More than 40% of treated hypertensives in the United States do not have their blood pressure under control. This is partly owing to non-persistence with prescribed medication, which occurs within 1 year in 32-53% of newly treated patients. Knowledge of factors related to non-persistence is limited, partly because previous studies have being conducted mostly in elderly patients enrolled in a single health insurance.
METHODS: Weighted logistic regression was used to identify factors associated with non-persistence in hypertensive patients from National Health and Nutrition Examination Surveys III (NHANES III) and NHANES 1999-2002 who had been prescribed antihypertensive medication.
RESULTS: Of 6100 participants, 903 were non-persistent (sampling weighted national prevalence of 12.5%), even though they had elevated blood pressure. Non-persistence was 12 times higher in patients <30 years than in those > or =50 years old (P < 0.001), 31% higher in men than in women (P = 0.01), and 43% higher in Hispanics, as compare to other racial groups (P = 0.03). Patients with low income were almost two times more likely to be non-persistent (P < 0.001). Having no health insurance increased non-persistence by 88% (P = 0.002), and patients who did not visit their doctor during the last year were 10 times more likely to be non-persistent than those who made at least one medical visit (P < 0.001).
CONCLUSIONS: In addition to young age, factors related to access to health care and medications (low income, health insurance, and visits to the doctor) were the main predictors of non-persistence. Policies that improve access to health care and patient follow-up may be of great impact in maintaining persistence.