The result of the study showed that only one third of hypertensive patients on pharmacologic treatment had a controlled BP (31%). Inadequate control of BP appears to be a prevalent problem challenging the primary care in Addis Ababa. The level of BP control found in this study (31%) is lower than obtained from HC based studies from Chile (59.7%) (20), Oman (39%) (21), Greece (55.6%) (22), USA (49.8 %) (23) and South Africa (57%)(24). This difference in the level of BP control might be due to a more aggressive strategy in the treatment of hypertension as the use of combination antihypertensive agents was common in most of the studies. In addition, difference in expertise of health professionals involved in the management of hypertension might have contributed to the discrepancy. Moreover, in three of the studies hypertensive patients on lifestyle modifications who were not on antihypertensive drugs were included (20, 23, 25)which could have contributed to a better control of BP than this study.
The level of BP control in this study was similar to the result obtained from hospital based studies conducted in Zimbabwe (32.8 %)(26), Kenya (33.4%)(27) and Nigeria (35.0%) (28). This similarity in the level of BP control might be is a result of the similarity in the inclusion criteria of the studies as only hypertensive patients on pharmacologic therapy were included in the studies similar to the present study. On the contrary, a study conducted in USA at different level of the health system showed 60% of treated hypertensive people to have a controlled BP(29)and hospital based studies from Adama, Ethiopia and Nigeria showed a BP control level of 43.6% (30) and 42% (31)respectively. This difference in level of BP control might have resulted from a more aggressive treatment in hospitals as patients attending hospitals have associated co morbidities.
The proportion of patients with controlled SBP and DBPwasalmost similar from a studyin Saudi Arabia (40.4% and 51.6%) (32)but lower than a study in USA (55.7% and 77.1%) (25). This difference in the level of control of SBP and DBP might be due to age related increase in SBP as large proportion of study participants (52.1%) were older than 60 years of age (33, 34). More importantly, level of healthcare USA is expected to be better than in Ethiopia in terms of resource and man power.
In the study, younger age was a contributing factor for poor BP control. Similar result was obtained from a study in Brazil (35).On the other hand, the result of other studies showed that patients aged younger than 60 years were more likely to have controlled BP than older patients (25, 27). Better BP control among the elderly in this study may be is because of an increased prevalence of comorbidities hence high probability of intensive treatment and/or a better rate of adherence.Additionally, health professionals could have shown more concern in counseling and ordering appropriate management for elders.
Consistent with our finding, a study in Chileat HC set up showed low education level to have a negative association with BP control(20). This is most likely associated with level of awareness on hypertension and adherence to life style modifications to decrease BP.Additionally, government employees, retirees and patients on private business were more likely to have uncontrolled BP than house wives. This might have resulted because of forgetfulness and hence non-adherence to antihypertensive medications.
In our study, being hypertensive for longer period of time (≥ 10 years)was found to be a significant predictor for not achieving target BP. This could be due to asymptomatic nature of the disease, a decrease in health seeking behavior from patients and clinical inertia(36).
More frequent BP monitoring is one of the important factors to achieve target BP (5, 15). We found weekly BP measurement to be a significant predictor to have controlled BP. Encouraging home-based BP measurement is one of the ideal interventionsthat may increase patients’ health seeking behavior, adjustment of life style and adherence with their medication.
Antihypertensive medication utilization pattern in this study was more of similar with a study conducted in South Africa(24). However, a study conducted in Chile(20)and USA(25) used ACEI more often than diuretics. This difference in frequent use of ACEI over diuretic may be is a result of large proportion of diabetic and CKD patients included in Chileand USA studies. Additional factor that might have contributed to this discrepancy include race (5, 19). The frequent use of alpha 2 agonist (methyldopa) in this studymight have resulted from gaps in knowledge among health professionals involved in the management of hypertension in the HCs or lack of other optional drugs.
Most (80%) of our study participants were prescribed a single antihypertensive agent. This was similar with a study conducted in Zimbabwe(70%) (26). However, different results were reported on studies from Chile(34%) (20) and USA (29%)(25). The high prevalence of antihypertensive monotherapy in this study might have contributed to the low BP control. To achieve optimal BP level, the use of multiple antihypertensive agents is recommended (5, 14-16, 19, 37). A study also showed the benefit of using multiple antihypertensive agents in order to achieve optimal BP control(20). The prevalent use of monotherapy might have resulted from lack of drug availability at health facility, unaffordability of drugs by patients and less aggressive treatment (26).
Switching to another drug and addition of a drug were the leading type of treatment modifications. This might be because most of the present study participants had uncontrolled BP (38). The treatment modification was low when compared to a study by Banegas et al (2004) which reported treatment modification in 49% of hypertensive patients from which addition of a drug and increasing dose were observed more frequently (39). This discrepancy might be is a result of aggressive treatment of hypertension in the later study and clinical inertia in the present study.
Almost all patients did not smoke which might be result to Ethiopian socio-cultural influence. More than one third of the study participants were overweight or obese and one fifth of the female as well as two third of the male participants had abdominal obesity. This result is different from the result of the study by Tesfaye et al conducted in Addis Ababa which showed 20% of males and 38% of females to have a BMI of ≥ 25 kg/m2; 12.9% of male and 64.6 of female to have abdominal obesity (7). This difference might be a result of difference in the age of the participants; predominance of elderly patients in the present study; difference in the characteristics of the study population; patients without a diagnosis of hypertension were included in the later study; or a change in the lifestyle of population of Addis Ababa. Since high BMI and increased abdominal circumference are risk factors for hypertension and uncontrolled BP among hypertensives, emphasis should be given to counsel patients on the importance of implementing life style modifications.
Strength and limitation of the study
This study gives insight into determinants of BP control practice in primary healthcare centers of Addis Ababa. BP measurements were analyzed as recorded in patient medical records, which reflect actual clinical practice, but may be subject to recording and measurement error. The finding of this study may not be generalizable to private practice or hospital settings.