Mortality in South Asians and Caucasians after percutaneous coronary intervention in the United Kingdom: an observational cohort study of 279,256 patients from the BCIS (British Cardiovascular Intervention Society) National Database

Abstract

Objectives: The purpose of this study was to compare baseline characteristics and medium-term prognosis in South Asian and Caucasian patients undergoing percutaneous coronary intervention (PCI).

Background: It is unclear whether South Asians undergoing PCI have worse outcomes than Caucasians.

Methods: We performed a retrospective analysis of 279,256 patients undergoing PCI from 2004 to 2011 from the British Cardiovascular Intervention Society national database, of whom 259,318 (92.9%) were Caucasian and 19,938 (7.1%) were South Asian (South Asian includes patients of Pakistani, Indian, Bangladeshi, or Sri Lankan ethnic origin). The main outcome measures were in-hospital major adverse cardiac and cerebrovascular events and all-cause mortality during a median follow-up of 2.8 years (interquartile range: 1.5 to 4.5 years).

Results: South Asians were younger (59.69 ± 0.27 years vs. 64.69 ± 0.13 years, p > 0.0001); more burdened by cardiovascular risk factors, particularly diabetes mellitus (42.1 ± 1.2% vs. 15.4 ± 0.4%, p > 0.0001); and more likely to have multivessel coronary disease than Caucasians. In-hospital rates of major adverse cardiac and cerebrovascular events were similar for South Asians and Caucasians (3.5% vs. 2.8%, p = 0.40). Unadjusted Kaplan-Meier estimates of all-cause mortality showed better survival for South Asians compared with Caucasians, after PCI for either acute myocardial infarction or angina. Age-adjusted analysis revealed increased mortality (hazard ratio: 1.24; 95% confidence interval: 1.18 to 1.30), but after adjustment for the substantial variation in baseline risk factors including diabetes, there was no significant difference between South Asians and Caucasians (hazard ratio: 0.99; 95% confidence interval: 0.94 to 1.05).

Conclusions: In this large, contemporary cohort of patients treated by PCI, South Asians were younger but had more extensive disease and major risk factors, particularly diabetes. However, after correcting for these differences, in-hospital and medium-term mortality of South Asians was no worse than that of Caucasians. This suggests that in South Asians, the high prevalence of diabetes exerts an adverse influence on mortality, but ethnicity itself is not an independent predictor of outcome.

Keywords: PCI; ethnicity; mortality.