Nonadherence to drug treatment is a major contributor to antihypertensive treatment failure. Mood disorders could impair the patient's desire and ability to follow physician's recommendations. We evaluated the role of symptoms of depression and anxiety on adherence to antihypertensive drug treatment.
We conducted a longitudinal cohort study in 20–70 years old patients starting antihypertensive drug treatment, without other chronic conditions, and not taking mood-modifying drugs. Severity of symptoms of depression and anxiety were evaluated at enrollment and 3, 6, 9, and 12 months of follow-up, using the Beck depression inventory-II (BDI-II) and the psychological general well-being index (PGWB), respectively. Treatment adherence was measured by pill count. Nonadherence was defined as taking <80% of the prescribed number of pills. Poisson regression was used to model the association of the exposures with adherence.
We enrolled 178 patients (58% male; mean age: 50 years; 508 follow-up visits). The risk of nonadherence was 52.6% in 12 months (95% confidence interval (CI): 46.1, 59.1). After adjusting for other risk factors, individuals with at least mild depression (BDI-II ≥14) and those with at least mild anxiety (PGWB anxiety score <22) were 2.48 (95% CI: 1.47, 4.18) and 1.59 (95% CI: 0.99, 2.56) times more likely to become nonadherent in the following 3 months, respectively.
Patients with at least mild anxiety and depression symptoms are at increased risk of becoming nonadherent to antihypertensive medication. Screening for depression and anxiety symptoms could be used to identify high-risk patients. Further evidence is needed to elucidate whether interventions targeting these conditions improve adherence.