Prevalence of obesity in asthmatic adults

Editor—Obesity is an increasing health problem, particularly in the affluent countries, and although the reported association (not necessarily causal relationship) with asthma is not new, Stenius-Aarniala et al have appropriately reported the effects of weight reduction in morbidly obese adults (body mass index 30-42) with asthma.¹ They have also suggested that, because of the high prevalence of obesity,² a large number of patients with asthma will also be obese.

To highlight the findings of the study, in the context of reporting the prevalence of obesity specifically among people with asthma, cross sectional data collected during a previously reported community study based in some of the socioeconomically deprived districts in Birmingham³ have been newly analysed.

Of the original 689 study subjects with asthma, 535 (77.6%) were adults (293 white Europeans, 242 South Asian) within the age group 18-59 years. Only 38.5% of these adult subjects had a body mass index (kg/m²) within the healthy range (18.5-24.9), whereas most were either overweight (36.4%, body mass index 25-29.9) or obese (19.6%, body mass index 30-39.9).

At the extremes, 1.7% were severely obese (body mass index >40) and 3.6% underweight (<18.4). The predicted forced expiratory volume in the first second did not vary significantly (range 76.6-79.3) between the different categories. Regression analysis in these subjects showed that there was also an association between body mass index and both age and sex but not with ethnic group. Data overall suggest that almost 58% of adults with asthma in this community were above their ideal body mass index measurements, but we cannot generalize as to the applicability of the reported study¹ and specifically whether weight reduction would have a similar impact in all overweight as well as obese individuals.