This report revealed two main unexpected findings: A high rate of Elevated BP among individuals not known to have hypertension (18.7%), a higher rate of elevated BP in individuals with a known diagnosis of hypertension (62.2%), and high rates of elevated blood glucose (79.1%). High rates of elevated BP and elevated BG identified through a health screening campaign in this Rwandan district were surprising given the rural characteristics of the district and relatively low population age (46.4±15.8 years).
Awareness and hypertension control in this study
This report identified a high prevalence of elevated BP in individuals not previously known to have hypertension. This finding confirms both a high prevalence and a poor awareness of HTN typical of 17 especially in Sub-Sahara Africa 6,22. However, it is lower compared to the pooled weighted awareness rate of 16.9% in 1990, 29.2% in 2000 and 33.7% in 2010 reported by Adeloye D et al 23 from population-based studies on hypertension in Africa. The availability of data on awareness rates of hypertension in sub-Saharan Africa (SSA) in general, and from rural areas in particular, are scattered and generated by a wide range of studies differing in methodology thus limiting the opportunity for reliable comparisons 7,24,25. However, the recent study by Chow CK et al 26 reports that only one in three individual is aware of their hypertension status (i.e. higher than in our study), and about only 8% have their blood pressure controlled (i.e. lower than in our study). The poor treatment control in African settings has been largely reported by other authors, however the 37.8% reported rate by this study is higher than the reported average of 23.4%.26 The high proportion of rural dwellers with uncontrolled hypertension in our study can be partially explained by geographically inaccessibility to health facilities for treatment monitoring.
High prevalence found in this study
This study identified an overall prevalence of Elevated BP of 21.2% (95% CI= 20.0-22.4%). A prior population-based study in Rwanda estimated the prevalence of HTN in people between 15 and 64 years old at 15.3% (16.4% for males and 14.4% for females) 22, indicating that ~1 million people are living with HTN in Rwanda. The reported rate of elevated BP in this study was also lower than the 27.7% reported by a workplace-screening program conducted in an urban Ethiopian setting.27 Other studies from rural areas of Sub-Saharan Africa have reported variable rates of HTN prevalence that ranges from 5–52% 8,28,29. Adeloye D et al 23 had estimated hypertension pooled prevalence pooled in Africa at 26.1% (95%CI: 23.6–33.6). In line with those other pooled data, the results presented in the current study confirm a serious concern of the rising prevalence of hypertension in rural Rwanda. This threat is further exacerbated by an under-resourced healthcare system; the nationwide network of healthcare clinics available to treat NCDs in Rwanda only serve approximately 80,000 patients, representing a coverage of <10% 30. These data indicate that the majority of Rwandan adults with HTN are not only untreated, but undiagnosed.
Participants’ characteristics in this study
The participant characteristics associated with elevated BP in this study are similar to the preliminary data reported by Muggli F. et al28 from another screening event held in the rural area of the District of Nyaruguru (Southern Rwanda) which found a much low prevalence of hypertension at 8.8%. However, that screening event reported a median age of 32 years, much younger than 46±16 years reported in this study. This lower age likely contributes to the low prevalence of hypertension found in their report. As reported in other studies, 7,10,17,29 gender was not significantly associated to elevated BP in our study. However, consistent with other studies, 25,31,32 advancing age was a significant predictor of elevated BP in this study.
The association between overweight and elevated blood pressure has been long-established, including in African populations. 15,33−35 This study revealed a high prevalence of overweight and obesity as noted in other prior studies conducted in rural Rwandan areas 22. The relationship between BP and anthropometric indices such as BMI, WC, waist to hip ratio (WHpR), and waist to height ratio (WHtR) have been described in others studies.33 Our study was not powered to assess this comparison between overweight indices, and some indices were not available for analysis. Therefore we added all raw data on weight, height, BMI and WC into analysis both univariate and multivariate after assess collinearity with correlation matrix between variables. The association between the BMI categories and the elevated BP was not conclusive in our study probably due to small sample size in cells in contrast with WC. Nevertheless, this finding is unexpected and further work is needed to validate the association identified in this study since these are in contrast with other reports from rural India 34 and Nigerian 35 which identify a higher BMI as a major risk factor for hypertension 18,36,37.
Other risk factors identified in multivariable analysis as independently associated to elevated BP are in line with previous Rwanda WHO STEPs study by Nahimana MR et al 22. In their nationwide study, a logistic regression model revealed that age, alcohol consumption, blood glucose levels, and raised BMI were significantly associated with hypertension, a finding confirmed in this study.
Implication for strategy for the prevention, diagnosis and treatment of hypertension in Rwanda
This study brings additional evidence to support tailored measures for the prevention, diagnosis and treatment of hypertension in rural populations in Rwanda. Recent reviews analysing root causes for poor blood pressure control in Rwanda38 and in Eastern Sub-Saharan Africa 39 highlight this unmet healthcare need. On a global scale, the World Health Organization (WHO) has created a target to reduce heart attacks and stroke by 25% by 202517, and the World Heart Federation (WHF) launched a roadmap focusing on raised BP awareness, treatment, and control during the 2015 World Health Assembly in Geneva. 40 Monitoring through systematically organized periodic screening campaigns for HTN, diabetes, and other NCD risk factors in rural population remains a key strategy for optimizing treatment and control 24. Early detection with opportunistic screening campaigns can also mitigate multiple barriers like poor health education literacy 38 and low socio-economic status. 39 However, given the need to balance competing healthcare priorities including infectious diseases, nutritional deficiencies, and maternal and perinatal morbidity and mortality, a reallocation of healthcare resources towards continuous monitoring of NCDs in LMICs is necessary.6
Study limitations
This study fills in a scientific data gap and its large sample size is adequate for subgroup comparisons. This is also one of the first studies to characterize the blood pressure and blood glucose profiles in a remote rural area in Rwanda through a community screening. However it has also some limitations. First, given the current study is not a systematic population-based screening, bias from participant self-selection likely influenced the results of this study. Second, given the cross-sectional design of this screening study, we are unable to determine temporality and causality in the study; therefore, causation can only be inferred. Third, the study reports only elevated BP and not prevalence of hypertension because the three blood pressure measurements were performed only on one occasion. Fourth, we were unable to explore the contribution of other risk factors such as unhealthy diet, salt intake, and psychosocial stress on the prevalence of hypertension because the related information were not available during casual data collection. Additionally, the quantification of alcohol intake and smoking where rather empirical in the region where traditional alcoholic drinks 41 and traditional pipe smoking were hard to define according to international standards 42. There might be also social desirability biases to underestimating some of the lifestyle and behavioural questions, such as smoking and alcohol consumptions. Despite these limitations, the study makes significant contribution and fills a substantial gap in the current Rwanda and regional context. The use of standardized and robust methodologies, tools and high response rate observed in the study increased its representativeness and strengthens its value in informing the CVDs prevention by enabling tailored preventive measures and optimize the treatment control.