Racial variation in cardiovascular morbidity and mortality in essential hypertension

Abstract

Objectives: To perform a longitudinal comparison of morbidity and mortality among white, south Asian and Afro-Caribbean hypertensive patients in relation to baseline demographic characteristics and clinic and ambulatory blood pressure variables.

Design: Observational follow up study.

Setting: District general hospital and community setting in Harrow, England.

Patients: 528 white, 106 south Asian, and 54 Afro-Caribbean subjects with essential hypertension who had undergone 24 hour ambulatory intra-arterial blood pressure monitoring.

Interventions: Follow up for assessment of all cause morbidity and mortality over a mean (SD) of 9.2 (4.1) years.

Main outcome measures: Non-cardiovascular death, coronary death, cerebrovascular death, peripheral vascular death, non-fatal myocardial infarction, non-fatal stroke, coronary revascularisation.

Results: South Asians had the highest all cause event rate of 3.46, compared with 2.50 (NS) and 0.90 (p = 0.002) events/100 patient-years for whites and Afro-Caribbeans, respectively. This was because of an excess of coronary events (2.86 v 1.32 events/100 patient-years in south Asians v whites, respectively; p = 0.002). Age (p < 0.001), sex (p < 0.001), race (south Asians : whites, hazard ratio 1.79; p = 0.008), diabetes (p = 0.05), previous history of cardiovascular disease (p < 0.001), and 24 hour ambulatory systolic blood pressure (p = 0.006) were independent predictors of time to a first event. Clinic blood pressure did not provide additional prognostic information.

Conclusions: South Asian origin was an independent predictor of all cause events, mainly because of an excess of coronary events in this group. Ambulatory but not clinic blood pressure was of additional value in predicting subsequent morbidity and mortality.

Figure 1

Follow up scheme for the 723 study patients.

Figure 2

Baseline and follow up clinic blood pressures in white, south Asian, and Afro-Caribbean subjects.

Figure 3

Incidence of non-cardiovascular, coronary, and cerebrovascular events in white, south Asian, and Afro-Caribbean subjects. *p < 0.01 v Afro-Caribbeans; **p < 0.01 v whites and Afro-Caribbeans.