Prevalence and incidence of asthma related to waist circumference and BMI in a Swedish community sample.

Both asthma and obesity have become more common in affluent societies during the recent decades and several studies have shown a correlation between the presence of asthma and obesity. In order to further study this association we have investigated a population from a community in southern Sweden, where almost all inhabitants had their body indices measured as part of a study on diabetes at a primary care centre. An asthma unit working with a structured care programme for asthma was available. This organisation enabled us to study whether body mass index and waist circumference was associated with having or developing asthma. There was a significant association between both overweight, increased waist circumference and asthma, P < 0.01. The risk for developing asthma was associated with increased body weight and abdominal circumference, P < 0.05. The increase in asthma morbidity in the overweight subjects was found almost exclusively in the non-atopic asthma patients. This study confirms earlier findings of an increased prevalence of asthma in obese and overweight patients. Increased obesity and especially abdominal obesity is thus a risk factor for asthma, which probably contributes to the high prevalence of asthma in affluent societies.