Target organ damage among subjects with high­normal blood pressure in a Nigerian tertiary health institution

ABSTRACT

Background: There is paucity of data on the relationship between high ­ normal blood pressure (BP) and target organ damage (TOD) in sub-Saharan Africa including Nigeria. This study therefore, aimed to assess target organ damage (TOD) among subjects with high ­ normal BP in comparison with hypertensives and subjects with optimal BP. Materials and Methods: The study was crosssectional and comparative conducted at Aminu Kano Teaching Hospital, Kano on eligible subjects aged 18 years and above. Three groups comprising of randomly selected subjects (high -normal (group 1), hypertension (group 2) and optimal BP (group 3)), with each group having 100 in number were studied. Funduscopy and relevant investigations including transthoracic echocardiography were carried out. High ­ normal BP was defined as systolic BP of 130 -139mmHg and/or diastolic BP of 80-89mmHg. Results: The mean age of subjects in group 1 was 27.32 ± 8.20 years and 60% were female, 34.04±6.25 years for group 2 and 53% were female, and 52.81 ± 13.3 years for group 3 and 56% were female (P = < 0.001). The most prevalent TOD was left ventricular hypertrophy,present in 62% of hypertensives, 14% of those with high-normal BP and 2% of those with optimal BP(P = <0.001). Micro albuminuria and slight increase in creatinine were found in 12.9% and 6% of subjects with high-normal BP; 25.7% and 25% of hypertensives and 4.1% and 3% of subjects with optimal BP. The study found a significant progressive increase in both cardiovascular disease risk factors and target organ damage (TOD) as BP increased across the blood pressure categories from optimal BP to high ­ normal BP and to hypertension (P = <0.05). Conclusion: Subjects with high-normal BP had significantly higher prevalence of both TOD and cardiovascular disease risk factors than those with optimal BP but lower than hypertensives, suggesting that efforts to control BP should start early to reduce the complications of high BP