Why is such an investigation of ethnic differences in disease important?

For the clinician, knowing about differences can improve the probability of diagnosis, treatment and prognosis. For the public health physician, it can highlight areas that need prevention programmes such as for type 2 diabetes or for coronary heart disease. For the physician concerned in ensuring equality, it encourages audit of access to treatments and outcomes for differing population groups.

For the researcher, differences can be used to formulate hypotheses to account for the disease variation: for example, why does the person who lives in or whose forefathers lived in the Indian subcontinent (here called Indo-Asian) have a high incidence of coronary artery disease but a low incidence of peripheral vascular disease? Clearly, such reasons could be genetic, epigenetic or more directly environmental.

For the publisher of international journals and or text books, differences in disease with differing ethnicity are very important to document for the readers. For too long observations have been made on Caucasians and for too long these observations have been assumed to be normal, even though access to equal care had been a popular subject for at least the past 20 years.2

What are the critical steps in an observational study looking at ethnicity disease variation?

The comparison needs to be based on an unbiased …