Anticoagulation control among patients on vitamin K antagonists in nine countries in Sub-Saharan Africa.

Vitamin K antagonists (VKA) is the primary anticoagulant in most settings of Sub-Saharan Africa. Understanding the quality of anticoagulation services in the continent is vital in optimising the intended benefits. This study assessed the quality of anticoagulation and associated factors among VKA-treated patients in nine SSA countries. We conducted a retrospective cohort study of randomly selected patients on anticoagulation from 20 clinics in Botswana, the Democratic Republic of Congo, Ethiopia, Gambia, Ghana, Mozambique, Nigeria, Tanzania, and South Africa. Eligible participants were those on VKAs for at least three months and with at least four international normalised ratios (INR) results in 2019-2021. We report the proportion of INR values in the therapeutic range, time-in-therapeutic range (TTR) using the Rosendaal method, and the proportion of patients with TTR ≥ 65% (optimal anticoagulation). The mean age was 51.1(16.1) years, and 64.2% were women. The most common indications for VKA included venous thromboembolism (29.6%), prosthetic valves (26.7%) and atrial fibrillation/flutter (30.1%). We analysed 6743 INR tests from 1011 participants, and of these, 48.5% were sub-therapeutic, 34.1% therapeutic, and 17.4% were supratherapeutic relative to disease-specific reference ranges. TTR was calculated for 660 patients using 4927 INR measurements. The median (interquartile range [IQR]) TTR was 35.8(15.9,57.2) %. Optimal anticoagulation control was evident in 19.2% of participants, varying from 2.7% in Tanzania to 23.1% in Ethiopia. The proportion of patients with TTR ≥ 65% was 15,4% for prosthetic heart valves, 21.1% for venous thromboembolism and 23.7% for atrial fibrillation or flutter. Countries with universal health coverage had higher odds of optimal anticoagulation control (adjusted odds ratio (aOR) 1.79, 95% confidence interval [CI], 1.15- 2.81, p = 0.01). Patients on VKAs for different therapeutic indications in SSA had suboptimal TTR. Universal health coverage increased the odds of achieving TTR by 79%. The evidence calls for more intensive warfarin management strategies in SSA, including providing VKA services without out-of-pocket payments.

Relationship between 24-hour blood pressure pattern and left ventricular structure and function in hypertensive Nigerians.

OBJECTIVE: Blood pressure variation throughout the day is known to have cardiovascular consequences. Left ventricular (LV) mass is more closely related to 24-hour blood pressure than casual blood pressure. Daytime blood pressure expectedly is higher than that of nighttime under normal circumstances. The effect of 24-hour blood pressure pattern on the left ventricular structure and function has not been examined in hypertensive Nigerians. The aim of our study was to assess the 24-hour blood pressure pattern and its relationship to the LV structure and function in newly diagnosed hypertensives in Nigeria. We hypothesized that 24-hour blood pressure was more related to left ventricular structure than casual blood pressure in hypertensive Nigerians. DESIGN: Cross-sectional study. SETTING: The study was carried out at the Cardiology Unit of the Department of Medicine, University College Hospital, Ibadan, South West Nigeria. PARTICIPANTS: Three casual blood pressure measurements were taken, while the participants were resting, using standardized digital blood pressure machine. Mean of the 3 measurements was used to categorize the participants as hypertensives or normotensives (controls). A calibrated Schiller BR-102 ABPM machine was used to measure the 24-hour blood pressure in 210 hypertensives and 202 normotensives (controls). Daytime and nighttime systolic (SBP) and diastolic blood pressures (DBP) were acquired every 20 minutes. Left ventricular mass was indexed by the allometric power of height (height 2.7) and left ventricular hypertrophy was considered present if LVM was > or = 49.2 g/m2.7 in males or > or = 46.7 g/m2.7 in females. MAIN OUTCOMES: The hypertensives and the controls were comparable in their demographic characteristics. Among the hypertensives, mean casual blood pressure and mean 24-hour blood pressure (SD) were 165(16)/96(8) mm Hg and 132(22)/84(15) mm Hg, respectively (P < .0001). 24-hour, day- and nighttime blood pressure were statistically related to left ventricular mass and indexed left ventricular mass in the hypertensives (r = .40 and .40, respectively for mean 24-hour SBP; r = .34 and .30, respectively for mean 24-hour DBP; r =.33 and .35, respectively for mean nighttime SBP, and; r = .22 and .24, respectively for mean nighttime DBP. The relationship was significant for mean 24-hour blood pressures but not for mean nighttime blood pressures for normal controls. There was no significant correlation between 24-hour blood pressure and indices of left ventricular function. CONCLUSIONS: Our study has shown a stronger relationship between 24-hour mean blood pressure and left ventricular mass compared with casual blood pressure. However there is no statistical relationship between 24-hour blood pressure and indices of left ventricular systolic and diastolic function.

Plasma catecholamines in Nigerians with primary hypertension.

BACKGROUND: Hypertension is the most common cardiovascular disease worldwide and is a major cause of morbidity and mortality. Increased adrenergic activity is thought to play a major role in the initiation and progression of the hypertensive state. Hypertension is more severe in Blacks when compared with White patients. Much of the evidence for the increased adrenergic activity is from studies in predominantly White participants. This study aims to evaluate the adrenergic system in Black Nigerian hypertensives by measuring their plasma catecholamines. METHODS: Eighty-two newly diagnosed hypertensives and 51 normal controls were recruited for the study. Blood was obtained from the participants after an overnight fast. Also, a 24-hr urine collection was obtained. Levels of plasma noradrenaline, adrenaline, renin, angiotensin converting enzyme (ACE), atrial natriuretic peptide (ANP), aldosterone and insulin levels were determined using HPLC. Fasting plasma glucose was also determined. RESULTS: Plasma noradrenaline level was higher while plasma adrenaline level was lower in the hypertensives. The hypertensives also had lower levels of plasma renin, ACE, and ANP. Systolic blood pressure negatively correlated with plasma adrenaline (r = -0.29, P < .001) and positively correlated with plasma noradrenaline (r = 0.31, P < .001). Renin and ANP also correlated negatively with blood pressure (r = -0.22, P = .012 and r = -0.34, P < .0001 respectively). CONCLUSIONS: Black Nigerian hypertensives demonstrate elevated levels of plasma noradrenaline when compared with normal controls. This is consistent with the hypothesis of the hyperadrenergic state in hypertension. Further studies are needed to relate the hyperadrenergic state to the racial differences in the severity of hypertension.

Blood pressure control and left ventricular hypertrophy in hypertensive Nigerians.

BACKGROUND: Hypertension is a disease characterized by end-organ complications, leading to high morbidity and mortality in many cases. People with untreated or uncontrolled hypertension often run the risk of developing complications directly associated with the disease. Left ventricular hypertrophy (LVH) has been shown to be a significant risk factor for adverse outcomes both in patients with hypertension and in the general population. We investigated the prevalence and pattern of LVH in a treated hypertensive population at the University College Hospital, Ibadan, Nigeria, using non-hypertensive subjects as control. Design and Setting : A prospective observational study performed at the University College Hospital, Ibadan, Nigeria. METHODS: Patients had 6 visits, when at least one blood pressure measurement was recorded for each hypertensive subject and average calculated for systolic blood pressure (SBP) and diastolic blood pressure (DBP) separately. The values obtained were used for stratification of the subjects into controlled and uncontrolled hypertension. Subjects also had echocardiograms to determine their left ventricular mass. RESULTS: LVH was found in 14 (18.2%) of the normotensive group, 40 (20.8%) of the uncontrolled hypertensive group and 14 (24.1%) of the controlled hypertensive group when left ventricular mass (LVM) was indexed to body surface area (BSA). When LVM was indexed to height, left ventricular hypertrophy was found in none of the subjects of the normotensive group, while it was found present in 43 (22.4%) and 14 (24.1%) subjects of the uncontrolled and controlled hypertensive groups, respectively. Significant difference in the prevalence of LVH was detected only when LVM was indexed to height alone. CONCLUSION: Clinic blood pressure is an ineffective way of assessing BP control. Thus in apparently controlled hypertensive subjects, based on office blood pressure, cardiac structural changes do remain despite antihypertensive therapy. This population is still at risk of cardiovascular events.