Prognosis for South Asian and white patients with heart failure in the United Kingdom

Editor—Blackledge et al recognise some of their findings as counterintuitive—for example, a huge excess of hospital admissions for heart failure in South Asians and yet a better outcome.¹ Such results could be artefactual.²

They use cases from 1998 to 2001 but the population in 1991. Were the ethnic codes used in hospital data the same as those used in the 1991 census, and were the populations called South Asian the same in the numerator and denominator? Table 1 shows that 85% of South Asian patients lived in the most deprived areas (Q5), compared with 38% of white patients. Figure 1 shows an age adjusted ratio for heart failure admission of about 2.8 in men and 4.3 in women, in apparent contradiction to the figures given in the abstract (3.8 and 5.2). There are typographical errors in table 2.

Figure 1.

Survival model for South Asian and white patients in cohort of new cases diagnosed with heart failure in hospital

We offer three alternative, testable explanations detailed in our electronic response.³

Firstly, South Asians' excess of heart failure out of proportion to coronary mortality or morbidity⁴ may be an artefact. For example, South Asians live in the inner city close to the local hospitals, while white patients are scattered across the city so may be less likely to be admitted to hospital with heart failure or more likely to be admitted outside Leicestershire.

Secondly, the better outcome in South Asians results from residual confounding by age.

Thirdly, the better outcome in the most deprived quintile reflects the high proportion of younger South Asians, with incomplete control of ethnic group and age as potential confounding factors.