Purpose of the Study. To examine the association between asthma and obesity among adults.
Study Population. Enrollees in a military managed care program, ages 17 to 96 years.
Methods. The investigators obtained data from 45 743 enrollment questionnaires that were completed between January 1997 and December 1998. After excluding those with emphysema/chronic bronchitis or implausible or missing body mass index (BMI) data, case-control analysis was performed on 2577 asthma cases and 36 347 controls. Because asthma was self-reported, the investigators selected random samples of 1000 cases and 1000 controls for verification. Status of the subject as a case or a control was verified by cross-referencing the cases and controls with medication profiles obtained from a computerized military health record system. Univariate analysis and multiple logistic regression was performed on both the larger case-control group and the verified case-control sample.
Results. Analysis performed on the larger, unverified study population showed that subjects with asthma were more likely to be female and younger and less likely to engage in exercise at least 3 times per week. When BMI was examined, enrollees with asthma were more likely to have BMIs 25.0 to 29.9 kg/m2 than enrollees without asthma (odds ratio [OR]: 1.2; 95% confidence interval [CI]: 1.1–1.4). Enrollees with asthma were also more likely to be obese (BMI ≥30 kg/m2). These findings held after adjustment for age and sex and when the analysis was performed on the verified sample. The OR for asthma increased with increasing BMI in both the larger study population and the verified sample. These findings remained in the final multivariate regression model for the larger study population and the verified sample, with a maximal asthma risk with BMI between 35 to 39.9 kg/m2 in the verified sample (OR: 3.8; 95% CI: 2.0–7.2).
Conclusion. BMI >25.0 is associated with asthma and increasing BMI is associated with increasing odds of asthma.
Reviewers’ Comments. This large study confirms findings of previously published smaller studies and suggests that obesity is a risk factor for asthma for the general adult population. Although selection bias may be a weakness of this study, its strength lies in the large study population. Whether obesity plays a causal role in the development of asthma or vice versa remains unclear.
- Copyright © 2002 by the American Academy of Pediatrics