Ethnic differences in outcome may be confounded by socioeconomic status

Editor—N Shaukat and colleagues analysed ethnic differences in risk factors for and the management and outcome of myocardial infarction.1 Their results show a significantly higher prevalence of diabetes and angina in patients presenting with myocardial infarction. They also confirmed what has been suggested by others—that outcomes after first myocardial infarction may be worse in patients whose ethnic origin lies in the Indian subcontinent than in Europeans.2 These differences may be related to patient management, and the authors imply that this may be a result of similar treatment being applied to different ethnic groups with different patterns of disease, a fact that may have been overlooked until now.

While these findings have potentially important implications for policy and practice, two notes of caution should be sounded. Firstly, the ethnic groups compared in this study were identified by analysis of surnames.3 Although this is a useful technique, searches based on surnames alone are inaccurate and result in rather heterogeneous groups.4 For example, a sample identified with Indian sounding surnames may include recent immigrants and second or third generation progeny of immigrants, together with non-south Asian wives of south Asian men or their mixed race children; all these groups have different risk profiles for coronary heart disease.

Secondly, in their analysis Shaukat and colleagues make no reference to socioeconomic position as a potential confounder. Even with relatively crude measures of socioeconomic position, twofold differences in the incidence of myocardial infarction have been shown between the poorest and richest quarters of the population.5 Similar stratification of hospital admissions for myocardial infarction and community deaths from myocardial infarction by socioeconomic position has been reported.5 It is likely that there were socioeconomic differences between the European and Indian origin groups which may have confounded the findings, although such differences were …