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I enjoyed the paper by Rose et alreviewing tuberculosis at the end of the century,1 but there was one curious piece of data which the authors did not address in the discussion—namely, that the rates in the Bangladeshi population which used to be exactly the same as in the Pakistani population are now only one third of the level. Does this indicate that Bangladeshi subjects have not been immigrating to the UK over recent years at the same rate as Pakistani subjects, or could it be that it reflects a genuine rate of reduction in tuberculosis in Bangladesh?
It is interesting that Bangladesh is one of the few countries which has received good reports from the WHO as to the effectiveness of their DOTS campaign.
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authors' reply We thank Dr Davies for his letter and are impressed by his attention to detail. As he correctly pointed out, rates of tuberculosis in Pakistani and Bangladeshi patients in England and Wales appear to have diverged since 1988, when both were less than 120 per 100 000 (115 and 104 per 100 000, respectively).1-1 Comparison of rates in these groups for 1988, 1993, and 1998 with WHO reported rates of tuberculosis in Pakistan and Bangladesh,1-2 however, reveals that Bangladeshi patients in the UK had rates of tuberculosis closely approximating those reported from Bangladesh (57v 58 per 100 000, respectively) for 1998. In contrast, patients of Pakistani origin in the UK appear to have had rates more than twice those reported from Pakistan (143v 61 per 100 000) in 1998.1-1 1-2
Dr Davies suggests that the lower rates of tuberculosis in patients of Bangladeshi origin in this country may be the result of a reduction in rates of tuberculosis in Bangladesh. WHO data, however, indicate that the rate of tuberculosis in Bangladesh has increased between 1988 and 1998.1-2
We believe that caution needs to be exercised when comparing crude rates of tuberculosis (and trends in those rates) in England and Wales for patients born abroad with rates in their countries of origin. Not only will the age and sex structures vary between these groups, but the proportion of the population that has recently emigrated will change over time. Rates of tuberculosis among recent immigrants have been observed to be especially high in England and Wales.1-1
These factors, together with an appreciation of the confidence intervals around any of the rate estimates for the subgroups in question, may account for the apparently large changes seen. The reassuring statistic is, however, that for the Indian subcontinent (India, Pakistan and Bangladesh) population in England and Wales as a whole, the overall rate of tuberculosis, even when standardised for age, place of birth and year of entry, has continued to decline.1-1