OBJECTIVES: To examine the association between self-reported medication adherence and self-reported drug-use among respondents of varying depression severity.

METHODS: Data were obtained from the 2019 US National Health and Wellness Survey. A total of 6038 respondents self-reporting prescription drug use for depression were identified. Respondents were categorized by depression severity using the Patient Health Questionnaire-9 (mild, moderate, moderately-severe, severe). The most commonly-used drugs were identified and self-reported adherence for each was assessed. Respondents taking more than one drug were excluded from analysis. Adherence was determined using a visual analogue scale from 0%-100% adherence, in 10% increments. First, adherence (100% vs. <100%) was compared across depression severity groups for the most common drug. Second, adherence-level (0%-100%, 10% increments) was compared across drugs for each depression severity group. Analyses were performed using chi-square test, and post-hoc comparison of group differences.

RESULTS: Across depression severity groups, Zoloft was the most commonly used drug, followed by Lexapro, Fluoxetine, Prozac, Sertraline, and Effexor. Zoloft had the highest rates of 100% adherence across groups: 56.93% for mild-depression, 45.95% for moderate-depression, 45.61% for moderately-severe-depression, and 36.5% for severe-depression respondents. Mild-depression respondents had significantly higher rates of 100% adherence to Zoloft compared to other groups (p<0.001 for all). Moderate- and moderately-severe-depression respondents had significantly higher rates of 100% adherence to Zoloft compared to severe-depression respondents (p<0.001 for all). For mild- and moderate-depression respondents, there was a significant relationship between adherence-level across drugs (p<0.001). For moderately-severe- and severe-respondents, there was no relationship observed between adherence-level across drugs.

CONCLUSIONS: Compared to other drugs, more respondents were 100% adherent to Zoloft; highest among mild-depression, followed by moderate-, moderately-severe-, and severe-depression respondents. Mild-/moderate-depression respondents had different adherence-levels depending on the drug, but moderately-severe-/severe-depression respondents were more likely to be non-adherent regardless of which drug they were taking. Additional analyses should explore factors influencing adherence across drugs.