In hypertensive patients, maintaining proper blood pressure control leads to favorable therapeutic outcomes, such as a reduction in HTN-related mortality and complications, which lowers the disease's global toll. Studies have shown that a significant majority of hypertensive patients still have uncontrolled BP despite receiving treatment (31,33). This study revealed that the overall magnitude of uncontrolled BP in Bishoftu town public health facilities was relatively high. The multivariable logistic regression analysis showed that salt intake, lack of physical activity, habitual coffee consumption, higher BMI, and non-adherence to antihypertensive medications were all independent predictors of uncontrolled BP.
This study showed that the magnitude of uncontrolled BP was found to be 58.8% (95% CI: 54˗64%). This is in line with studies conducted in Tikur Anbesa General Specialized Hospital, Addis Ababa (59.9%) (34), Debre Tabor District Hospital, Northwest Ethiopia (57.1%) (20), Bale Zone Public Hospitals (56.7%) (35), Bedele General Hospital, Southwest Ethiopia (56.2%) (17), Public Health Facilities in Dessie City, Northeast Ethiopia (55.8%) (36), hospitals in Yaoundé, Cameroon (63.2%) (21), and a national survey in Vietnam (54.1%) (38). However, it was higher than studies done at Nekemte Referral Hospital, Western Ethiopia (36.4%) (19), studies done at the University of Gondar Referral Hospital, Northwest Ethiopia (37% and 49.6%) (15,39), a primary care facility in South Africa (43%) (40) and studies conducted in Thailand (41), Chile (29), and Spain (42), which revealed uncontrolled BP of 24.6%, 36.9%, and 44.6%, respectively. Moreover, the magnitude of uncontrolled BP in this study was lower than in two studies done in Zewditu Memorial Hospital, Addis Ababa (73.8% and 69.9%) (2,43), and studies in Regional Referral Hospital, Kenya (44), and Jordan (45), which showed 66.6% and 67.1% of uncontrolled BP, respectively.
These differences could be explained by the fact that in our study, the majority of the patients had regular follow-up visits at a dedicated health facility, as well as the difference in study design and sample size. Furthermore, the disparity could be attributed to sociocultural and behavioral differences among the study population as well as differences in the expertise of healthcare professionals involved in the management of HTN and healthcare services in the study settings. In addition, the inconsistency may also be linked to differences in antihypertensive drug adherence rates and variations in the criteria utilized to classify hypertensive patients as having uncontrolled or controlled BP. Most studies used the JNC7 guideline (14), which employed a cutoff value of >140/90 for non-diabetic patients and >130/80 for diabetic patients to define uncontrolled BP, but the current study followed the JNC8 guideline (9).
In this study, hypertensive patients who added salt to their food had 2.5 times higher odds of uncontrolled BP compared to hypertensive patients who used no salt in their food. This finding is consistent with studies from the University of Gondar Referral Hospital and Debre Tabor District Hospital in Northwest Ethiopia (15,20), which found that patients who used top-added salt on a plate were less likely to have optimal BP control than patients who did not use top-added salt. Studies from Zimbabwe (46) and Southern China (47) have also shown an association between salt consumption and BP. This can be explained by the fact that salt affects the body's natural sodium balance, leading to fluid retention and raising the pressure imposed by the blood on blood vessel walls, resulting in high blood pressure (48).
Physical activity was another significant factor associated with uncontrolled BP. In this study, the odds of uncontrolled BP among hypertensive patients not involved in physical activity were 1.4 times greater compared to those of hypertensive patients involved in physical activity. This finding is similar to studies conducted at Ayder Comprehensive Specialized Hospital in Tigray, Ethiopia (16); Nekemte Referral Hospital in Western Ethiopia (19); and Southern China (47). Patients who engaged in physical activity were more likely to have optimal BP control than those who did not, according to studies conducted at the University of Gondar Referral Hospital and Debre Tabor District Hospital in Northwest Ethiopia (15,20). This can be justified by the fact that regular exercise strengthens the heart, allowing it to pump more blood with less exertion. So, when the heart is working less to pump blood, the strain on the arteries lessens, reducing BP. Physical activity also lowers high BP by lowering body weight, boosting renal function, and lowering systemic vascular resistance (vasoconstriction regulation), plasma norepinephrine, insulin sensitivity, and renin activity (49,50).
In this study, in comparison to non-coffee-drinking hypertensive patients, habitual coffee users had 4.5 times the odds of having uncontrolled blood pressure. This is similar to a study conducted in Spain (51) which showed habitual coffee consumption was statistically associated with uncontrolled BP in hypertensive patients. This may be due to Caffeine has been hypothesized to elevate blood pressure by several mechanisms, such as sympathetic overactivity, adenosine receptor antagonism, elevated norepinephrine release by direct effects on the adrenal medulla, renal effects, and renin-angiotensin system activation. Conversely, different studies have produced inconsistent findings about the relationship between blood pressure and coffee consumption (52,53). The nature of the association between coffee consumption and BP is still unclear, and further studies are required to establish the association between uncontrolled BP and habitual coffee consumption.
This study revealed that hypertensive patients who were overweight and/or obese had two times higher odds of uncontrolled BP compared to those who were normal. This finding is in agreement with studies done at Jimma University Teaching and Specialized Hospital, Ethiopia (21); Ayder Comprehensive Specialized Hospital, Tigray, Ethiopia (16); Zimbabwe (46); and Southern China (47). A study done at the University of Gondar Referral Hospital, Northwest Ethiopia (15), also found that the likelihood of BP control was reduced by 50% for overweight and 44% for obese patients compared with their counterparts. The justification could be that a higher BMI (overweight and obesity) causes a state of chronic volume overload because of the increased demands on the circulatory system to move blood through vast and comparatively low-resistance adipose tissue. The renin-angiotensin system, the proportion of intra-abdominal and intravascular fat, sodium retention that raises renal reabsorption, and the sympathetic nervous system are all thought to play essential roles in the etiology of obesity-related hypertension (54,55).
Adherence to medications is critical for preventing the effects of HTN-related morbidities and mortality. One of the main causes of poor BP control is poor adherence to medication, which also affects the efficacy of health outcomes broadly and dampens the optimal therapeutic values. In line with studies conducted in Nekemte Referral Hospital, Western Ethiopia (19); Debre Tabor District Hospital, Northwest Ethiopia (20); Ayder Comprehensive Specialized Hospital, Tigray, Ethiopia (16); Yaoundé, Cameroon (37); and Southern California, USA (56), this study showed patients who were non-adherent to their anti-hypertensive drugs were more likely to have uncontrolled BP than those who were adherent. This is due to the fact that anti-hypertensive drugs decrease and manage high BP by boosting vasodilatation, reducing vasoconstriction, raising urine output, and preventing sympathetic heart activation (57) and good antihypertensive medication compliance is crucial for managing hypertension and lowering BP.
Limitations of the study
Due to the cross-sectional study design used in this study, it is impossible to determine temporal relationships and difficult to confirm the causal-effect relationship between the dependent and predictor variables. Moreover, there might be recall and social desirability biases since the study participants' behavioral practices were based on self-reports and the performance of these behaviors was not observed or validated.