Several studies have investigated factors affecting medication adherence. This study shows that the level of adherence to antihypertensive medications is low. In this sample the adherence rate to hypertension treatment was found to be only 42%, which is similar to the study conducted in Al-Khobar and higher than the study conducted in Taif where adherence rate was found to be 47 and 34.7%, respectively [6, 8]. Other studies conducted in different countries reported adherence rates ranging from 15 to 88% [22,23,24,25]. This discrepancy in adherence rate is potentially due to the differences in population characteristics, medication adherence assessment tools, and healthcare systems.
The association between sociodemographic and socioeconomic factors and adherence level has been investigated in several studies. In a study done in Hong Kong, older patients were found to be more adherent. However, in this study, there was no association between age and adherence. In another study done in the United States, female patients were less adherent to hypertension medication compared to male patients . A study conducted in Malaysia reported that female patients were more adherent than male patients . Our study showed that there was no significant relationship between gender and adherence. A meta-analysis suggested that the association between age, gender, and adherence level is weak . The results of our study also demonstrate no significant relationship between marital status and educational level with adherence, which is similar to findings reported by other studies [9, 27].
Previous research found that shorter traveling time from residence to the healthcare facility could increase patients’ adherence . A study in Ethiopia found that the adherence level was lower in patients who lived more than 10 km from healthcare facilities . A cross-sectional observational study done in Northwest Ethiopia indicated that patients who live less than 10 km from the healthcare facility had an adherence rate of 74% compared to 58% for patients who live far from the healthcare facility . As the authors attributed this problem to poor infrastructure and lack of transportation in Ethiopia, the study suggested that shorter traveling time from residence to the healthcare facility could increase patients’ adherence . In this study, distance from home to the clinic was not associated with hypertensive treatment. These differences may be due to the higher level of car ownership in Saudis Arabia which makes it easier to access health care facilities .
Only 8.8% of the participants reported not taking their medication when it is not available at the hospital pharmacy. This low percentage may be explained by the multiple community health centers in Saudi Arabia which provide free health care including medications dispensing. Moreover, the medication cost at private pharmacies in Saudi Arabia is affordable for most patients. According to the published Saudi Hypertension Management Guidelines the prices of the antihypertensive medications ranges between 7 to 118 Saudi Riyal (about 2 to 31 US Dollar) .
Many patients with hypertension will need two or more antihypertensive medications to achieve goal blood pressure . In this sample significant association was observed between the number of medications and adherence level. The adherence rate among patients taking less than four medications was 47.1% compared to 31.3% to those who take four or more medications. Similarly, other studies reported the negative association between the number of medication and adherence levels [29, 32].
Findings indicate that patients with multiple comorbidities were less adherent to antihypertensive medication, which is inconsistent with a previous study done in Taif which showed a negative association between the presence of comorbidity and adherence level . This may be related to the fact that most patients with multiple comorbidities require taking multiple complex medications.
The result of our study showed that the patient who visited the clinic once in the last year were more adherent than the patient who visited the clinic more than once. This could be explained by that most patients with multiple comorbidities and on multiple medications frequently visit the clinic for issues related to their disease and to refill prescriptions.
Our study demonstrated the positive association between knowledge and adherence levels. Patients who had good knowledge were more adherent to the treatment . Previous studies showed that patients who know the ideal target blood pressure level were more adherent to their medications [16, 20]. In this study, only 64.4% of the participants knew the ideal target of blood pressure and 40.8% of the patients believe that hypertension can be cured. A study conducted in Rajshahi, Bangladesh found that 65.8% of the patients believe that hypertension is curable. Patients how have been educated by their physicians and healthcare providers were more adherents to treatment as they have a better understanding of the disease nature, the ideal target of blood pressure, and the complications of hypertension . Therefore, patient education in disease nature and management is considered a key factor in the treatment of hypertension.
The study findings were based on self-reported survey. Self-reported data is a common method used in a cross-sectional study. However, self-reported data is subjected to biases such as response and recall biases that can lead to under- or overestimation of findings. On the other hand, adherence in this study was measured based on a validated self-report adherence scale and knowledge was tested based on evaluated and reviewed assessment items by two independent family medicine consultants. Moreover, this study conducted in one of the largest medical cities that serves a large community in the capital city Riyadh. Due to the study design and sampling method, study findings cannot be generalized and temporal relationships cannot be established between risk factors and adherence. Nevertheless, this study provides a snapshot of adherence to antihypertensive medication status and associated determinates among outpatients. Future large scale longitudinal studies will contribute to a better understanding of adherence status and associated factors among hypertensive patients.