Concerns about medications mediate the association of posttraumatic stress disorder with adherence to medication in stroke survivors

Abstract

Objectives: Post-traumatic stress disorder (PTSD) can be a consequence of acute medical events and has been associated with non-adherence to medications. We tested whether increased concerns about medications could explain the association between PTSD and non-adherence to medication in stroke survivors.

Design: We surveyed 535 participants aged 40 years or older who had at least one stroke or transient ischaemic attack in the previous 5 years.

Methods: We assessed PTSD using the PTSD checklist-specific for stroke, medication adherence with the Morisky Medication Adherence Questionnaire, and beliefs about medications with the Beliefs about Medicines Questionnaire. We used logistic regression to test whether concerns about medications mediated the association between stroke-induced PTSD and non-adherence to medication. Covariates for adjusted analyses included age, sex, race, comorbid medical conditions, stroke-related disability, years since last stroke/TIA, and depression.

Results: Symptoms of PTSD were correlated with greater concerns about medications (r = 0.45; p < .001), and both were associated with medication non-adherence. Adjustment for concerns about medications attenuated the relationship between PTSD and non-adherence to medication, from an odds ratio [OR] of 1.04 (95% confidence interval [CI], 1.01-1.06; OR, 1.63 per 1 SD) to an OR of 1.02 (95% CI, 1.00-1.05; OR, 1.32 per 1 SD), and increased concerns about medications remained associated with increased odds of non-adherence to medication (OR, 1.17; 95% CI, 1.10-1.25; OR, 1.72 per 1 SD) in this fully adjusted model. A bootstrap mediation test suggested that the indirect effect was statistically significant and explained 38% of the association of PTSD to medication non-adherence, and the direct effect of PTSD symptoms on medication non-adherence was no longer significant.

Conclusion: Increased concerns about medications explain a significant proportion of the association between PTSD symptoms and non-adherence to medication in stroke survivors.