The prevalence of hypertension and stroke survivors in the polluted environment : a case study of rural Niger Delta

Background The risk of hypertension and/or stroke and prolonged exposure to crude oil pollution and gas flares remains unexplored. This was examined in the rural Niger Delta communities where decades of rampant oil and gas pollution and institutional neglect have been linked to increased cardiovascular diseases, poverty, and underdevelopment. Study aim and Objectives The aim of the study was to assess the prevalence of hypertension and stroke in the Niger Delta region. The overall objectives were to conduct a systematic review and meta-analysis of the prevalence of hypertension in Niger Delta region and the prevalence of stroke in low- and middle-income countries (LMICs) including Nigeria; and to conduct a survey to evaluate the relative prevalence and correlates of both hypertension and stroke. Methods Relevant databases were searched and articles reporting hypertension and stroke prevalence were systematically reviewed to obtain a pooled prevalence estimates and secular trends based on the random-effect model. In the cross-sectional survey, 2,028 resident adults (aged 18-80) were recruited in both oil/gas polluted and non-polluted communities. Prevalence of hypertension and stroke and other important measures were examined and compared between the two communities. Results The review found a continuous increase in the prevalence of hypertension in the region such that the estimates have been increasing by 8.31% every 5 years. For stroke, the lowest prevalence was found in sub-Saharan Africa including Nigeria (3.5 per 1000, 95% CI, 1.9-5.7). However, the only study conducted in the rural Niger Delta found a higher prevalence compared to other areas in Nigeria and in sub-Saharan Arica (8.51 per 1000 95% CI, 3.9-16.1). In the cross-sectional survey, the study found that one-third of participants were hypertensive (37.4%) while 27 stroke with a crude prevalence of 13.31/1000 persons (95% CI, 8·32-18·31) were found. In the adjusted model, participants living in oil-polluted areas were almost 5 times as likely to have developed hypertension (adjusted odds ratio (aOR) = 4.85, 95% confidence interval (CI): 1.84-112.82) compared to participants in non-polluted areas. Age-adjusted prevalence of stroke was 14.6/1000 person, which is about 7-folds higher than outside the Niger Delta region, and is the highest ever recorded in Africa as a whole. The study also found that participant’s age, education attainment, and obesity modify the association between pollution status and risk of hypertension. In particular, age modifies the association between pollution status and risk of hypertension. Conclusion The increased prevalence of hypertension and stroke is consistent with ongoing epidemiological and environmental transitions. The study findings have huge socioeconomic implications in the Niger Delta population particularly in the rural oil and gas hosts-host communities suggesting a potential interplay between socioeconomic, lifestyle and environmental factors. The findings could be useful for screening purposes to identify high-risk population before a diagnosis is made and to target interventions appropriately. The study findings need to be investigated further in longitudinal studies. The influence of other extrinsic factors underscores the need for improved surveillance and better management of undetected or uncontrolled high blood pressure.