The reliability and validity of the 8-item Morisky Medication Adherence Scale (MMAS-8) was assessed in a sample of Iranian hypertensive patients. In this multi-center study which lasted from August to October 2014, a total of 200 patients who were suffering from hypertension (HTN) and were taking anti-hypertensive medication(s) were included. The cases were accessed through private and university health centers in the cities of Tehran, Karaj, Kermanshah, and Bafgh in Iran and were interviewed face-to-face by the research team. The validated Persian translation of the MMAS-8 was provided by the owner of this scale. This scale contains 7 questions with "Yes" or "No" response choices and an additional Likert-type question (totally 8 questions). The total score ranges from 0 to 8 with higher scores reflecting better medication adherence. Mean (±SD) overall MMAS-8 score was 5.57 (±1.86). There were 108 (54%), 62 (31%), and 30 (15%) patients in the low, moderate, and high adherence groups. Internal consistency was acceptable with an overall Cronbach's ? coefficient of 0.697 and test-retest reliability showed good reproducibility (r= 0.940); P< 0.001. Overall score of the MMAS-8 was significantly correlated with systolic BP (r= - 0.306) and diastolic BP (r= - 0.279) with P< 0.001 for both BP measurements. The Chi-square test showed a significant relationship between adherence level and BP control (P= 0.016). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the scale were 92.8%, 22.3%, 52.9%, and 76.7%, respectively. The Persian version of the MMAS had acceptable reliability and validity in Iranian hypertensive patients. This scale can be used as a standard and reliable tool in future studies to determine medication adherence of Persian-speaking patients with chronic conditions.

Background

Comorbidity has been noted as a potential barrier to proper adherence to antihypertensive medications.

Objectives

We decided to investigate whether comorbidity could significantly affect adherence of Iranian patients with hypertension to their medication regimen.

Patients and methods

Two hundred and eighty consecutive hypertensive patients were interviewed in 4 cities of Iran. The 8-item Morisky medication adherence scale (MMAS-8) (validated in Persian) was used to assess medication adherence. This scale determines adherence by scores as lower than 6 (low adherence), 6 or 7 (moderate adherence), and 8 (high adherence). Comorbidity was considered as any concomitant medical condition, which necessitates the patient to take medicine for a minimum of 6 months prior to the interviews.

Results

The most common comorbid conditions were ischemic heart disease (65 patients, 23.2%), diabetes mellitus (55 patients, 19.6%), and dyslipidemia (51 patients, 18.2%). Mean (± SD) MMAS-8 score in comorbid group was 5.68 (± 1.85) and in non-comorbid hypertensive patients, it was 5.83 (± 1.91) (P = 0.631). Mean (± SD) number of comorbidities was 1.53 (± 0.75) in low adherence group compared to 1.54 (± 0.77) in moderate/high adherers (P = 0.98). With increasing the number of comorbid diseases, the proportion of patients with high adherence decreased successively from 20% in those with no comorbid disease to 14.1% in those with one or two comorbid conditions, and finally 11.1% in those with 3 to 5 comorbid conditions.

Conclusions

With increasing the number of comorbid conditions, the proportion of patients with high adherence decreases. In our opinion, this finding is a useful clinical note for healthcare providers when managing patients with hypertension who have other medical problems at the same time.