Pulse pressure, renal function and mortality in hospitalized Congolese patients with arterial hypertension

Objective. To assess renal function and mortality in African patients hospitalized for hypertension-related disorders. Methods. Blood pressure, weight, height, pulse rate, waist circumference, medical history, tobacco and alcohol habits, plasma glucose, blood hemoglobin and serum creatinine were obtained on admission and the outcome (death or survival) was recorded at discharge in 401 consecutive hypertensive patients (129 women, 118 newly diagnosed, 157 on current antihypertensive medication). Body mass index and eGFR were computed according to published formulas. R wave voltage >= 1.3 mV in lead aVL on a 12 lead ECG defined left ventricular hypertrophy.

Results. Average values were 54 years for age, 178, 106 and 72 mmHg for systolic, diastolic and pulse pressure, 68kg for weight, 169cm for height, 24.4kg/m² for BMI, 98cm for waist, 11.4 g/dl for hemoglobin, 112mg/dl for plasma glucose, and 82ml/min/1.73m² for eGFR.

In no patient was BP < 140/90 mmHg on admission, chronic kidney disease (CKD) with eGFR below 60 ml/min/1.73 m² was observed in 47 patients (11.7%), 8 of whom (6.8%) were naive patients, 24 untreated (19%) and 15 (9.6%) on antihypertensive medication. CKD predominated among diabetics and those with central obesity whilst LVH was shown in fewer CKD patients. eGFR was positively correlated to blood hemoglobin and inversely to age, blood pressure, known duration of hypertension and plasma glucose level in the whole study population, in naive patients and in those with CKD taken  separately (all p<0.05). The association between eGFR and pulse pressure persisted after adjustment for age, gender, plasma glucose and duration of hypertension. 89 deaths (22.2%), occurred during the hospitalization period.

Mortality was higher (p<0.0001) in CKD patients (n=36; 76.6%) than in those with normal renal function (n=53; 17.6%). eGFR was lower in CKD deceased patients whose pulse pressure was higher compared to survivals. Mortality was higher in CKD patients with diabetes or central obesity; it was lower in those on antihypertensive treatment at admission.

Conclusion. The present data indicate that pulse pressure is an independent determinant of the severity of renal function deterioration and outcome in black patients with arterial hypertension. Keywords: Pulse pressure, kidney function, mortality, hypertension, Africans.