Effectiveness of motivational interviewing on medication adherence among Palestinian hypertensive patients: a clustered randomized controlled trial

BACKGROUND: This trial aimed to evaluate the effectiveness of motivational interviewing (MINT) among medication non-adherent hypertensive patients attending primary healthcare centres in Gaza Strip. METHODS AND RESULTS: A clustered randomized controlled trial was run among 355 hypertensive participants; who were identified as non-adherent by a self-reported adherent scale and were recruited from 10 centres by two stages cluster random sampling approach (five centres were randomly allocated to each group). Standard of hypertension care was provided to 173 participants, parallel to 182 one who received their standard of care including non-blinded MINT sessions for 3 months. The change in medication adherence status was the primary outcome and within-patient changes of systolic blood pressure (SBP), diastolic blood pressure (DBP), self-efficacy and intrinsic motivation were the secondary outcomes. Data were collected via an interview-based structured questionnaire and were analysed by generalizing equation estimation model adjusting for covariates. The results showed a significant improvement in medication adherence status among participants in the intervention group (n = 159) [OR= 6.28; 95% confidence interval (CI): 3.20, 12.33; P < 0.001] compared with those in the control group (n = 151). Moreover, there were significant drops in both SBP (OR = 0.18; 95% CI: 0.06, 0.55; P = 0.002) and DBP (OR = 0.26; 95% CI: 0.09, 0.76; P = 0.013) and significant positive changes in both within-patient's self-efficacy (OR = 15.4; 95% CI: 3.9, 60.6; P < 0.001) and intrinsic motivation (OR = 31.7; 95% CI: 13.9, 71.9; P < 0.001). CONCLUSION: Standard of care including MINT is an effective client-centred approach which promoted medication adherence, decreased mean blood pressure, and improved self-efficacy and intrinsic motivations among hypertensive patients.