Ethnic disparities in the incidence, presentation and complications of malignant hypertension

BACKGROUND: The incidence of malignant hypertension has declined after the introduction of antihypertensive agents. However, previous reports have suggested that malignant hypertension may be relatively common in multi-ethnic populations. The aim of this study was to compare ethnic disparities in the incidence, clinical characteristics and complications of malignant hypertension. METHODS: A retrospective cohort study on malignant hypertension in a multi-ethnic population in Amsterdam, the Netherlands, between August 1993 and August 2005. RESULTS: A total of 122 patients with malignant hypertension were included, mean age 44 years (+/- 12), 66% were men and 47% were black. The incidence rate remained approximately 2.6 (+/- 0.9) per 100,000 per year and was higher among blacks. Black individuals had higher systolic blood pressure (234 +/- 23 versus 225 +/- 22, P = 0.03) and more renal dysfunction compared with white individuals (39% with serum creatinine > 300 micromol/l versus 22%, P = 0.04). Hypertension was previously diagnosed in 58% of all patients, 37% received medication, and 23% stopped their drugs before admission. Health insurance was absent in 25% of black and 2% of white patients (P < 0.01). Secondary causes were identified in 40% of white and 10% of black subjects (P < 0.01). After a mean follow-up of 4.0 +/- 3.2 years 10% had died and 19% needed renal replacement therapy. Renal failure was more frequent in black than in white individuals (hazard ratio 2.8; 95% confidence interval 1.1-7.2), but mainly because of higher serum creatinine levels at presentation. CONCLUSION: The incidence of malignant hypertension and related renal complications is higher in black compared with white individuals. These differences may be explained by ethnic disparities in blood pressure control, drug adherence and insurance status.