Does obesity influence target organ damage and outcomes in patients with malignant phase hypertension? The West Birmingham Malignant Hypertension Project

Several studies have suggested that hypertension has a stronger detrimental impact on cardiovascular outcome in lean than in obese persons, but neutral or opposite results have also been reported. We investigated the impact of baseline body mass index (BMI) at presentation with the most severe form of hypertension, that is, malignant phase hypertension (MPH) on the primary outcome of ` death or dialysis' in these patients. A total of 184 patients (overall mean (s. d.) age 48 (13) years; 61% male; 62% White-European; 20% African-Caribbean, 18% South-Asian) from the West Birmingham MPH Register were included. The patients were grouped according to their BMI (underweight, normal weight, overweight and obese groups). Ninety-three primary outcomes occurred during a median (interquartile range) follow-up of 10.7 (5.8-18.6) years. No significant baseline differences in age or ethnicity were seen between the study groups. Overweight and obese patients included a larger proportion of females, but less smokers than those underweight or of normal weight. There was no inter-group difference in retinopathy (P-0.25), proteinuria (P=0.08), haematuria (P=0.56) and left ventricular hypertrophy (P 0.14). In univariate analyses, BMI was predictive of death or dialysis (0.95 (0.90-1.00), P=0.046) but multivariate analyses showed that only baseline age (odds ratio (95% confidence intervals) 1.06 (1.03-1.09), P=0.001), smoking (2.89 (1.40-5.92), P<0.004), creatinine level (1.01 (1.01-1.02), P=0.001) and estimated glomerular filtration rates (0.99 (0.93-1.00), P=0.047) were independently associated with death or dialysis. BMI was not an independent predictor of adverse outcomes in MPH patients. Age, smoking status, creatinine levels and estimated glomerular filtration rates at diagnosis of MPH were independent predictors for death or dialysis in this high-risk population of hypertensive patients.