Mediating roles of medication-taking self-efficacy and depressive symptoms on self-reported medication adherence in persons with HIV: a questionnaire survey

Abstract

Background: To date, only a few studies have examined the mediating role of self-efficacy on the relationship between depressive symptoms or perceived social support and medication adherence in persons with HIV.

Objectives: The purpose of this study was to examine the impact of perceived social support, depressive symptoms and medication-taking self-efficacy on self-reported medication adherence in persons with HIV. A proposed comprehensive model included three mediation hypotheses in order to examine the mediating roles of medication-taking self-efficacy and depressive symptoms.

Method: Baseline data from "Adherence to Protease Inhibitors" were used. The 215 persons with HIV aged 19-61 (mean=40.7, S.D.=7.58) were recruited from multiple sites in Pittsburgh, PA (USA) and through self-referral. The participants were assessed using the Beck Depression Inventory, Interpersonal Support Evaluation List, the Medication Taking Self-Efficacy Scale, and the modified Morisky Self-report Medication Taking Scale. Structural equation modeling (EQS version 6.1) was used. The Satorra-Bentler Scaled chi(2) test statistics (S-B chi(2)), Comparative Fit Index (CFI), and the Standardized Root Mean Squared Residual (SRMR) were used to assess the fit of a comprehensive model including three mediation hypotheses.

Results: A comprehensive model with the three hypotheses showed a good model fit (S-B chi(2) (24, N=215)=69.06, p<.001; CFI=.95; SRMR=.057). Medication adherence self-efficacy fully mediated the prediction of self-reported medication adherence by perceived social support and depressive symptoms. Depressive symptoms partially mediated the prediction of medication-taking self-efficacy by perceived social support.

Conclusions: The findings of this study provide researchers with increased understanding of the mediating role of medication-taking self-efficacy beliefs between selected psychological variables and self-reported medication adherence in persons with HIV. Future studies need to test the moderating effect of gender, ethnicity and risk factors for HIV on this model and the intervention effect of self-efficacy beliefs using longitudinal data.

Figure 1. The conceptual model of this study

*parentheses indicate the changes of the relationship between independent and dependent variables after adjusting for a mediator

Figure 2. Final model of this study

* p<.01; **p<.001