Overweight, obesity, and incident asthma: a meta-analysis of prospective epidemiologic studies

Abstract

Rationale: Although obesity has been implicated as an asthma risk factor, there is heterogeneity in the published literature regarding its role in asthma incidence, particularly in men.

Objectives: To quantify the relationship between categories of body mass index (BMI) and incident asthma in adults and to evaluate the impact of sex on this relationship.

Methods: Online bibliographic databases were searched for prospective studies evaluating BMI and incident asthma in adults. Independent observers extracted data regarding annualized asthma incidence from studies meeting predetermined criteria, within defined categories of normal weight (BMI < 25), overweight (BMI, 25-29.9), and obesity (BMI >or= 30). Data were analyzed by inverse-variance-weighted, random-effects meta-analysis. Stratified analysis between BMI categories and within sex was performed.

Results: Seven studies (n=333,102 subjects) met inclusion criteria. Compared with normal weight, overweight and obesity (BMI >or= 25) conferred increased odds of incident asthma, with an odds ratio (OR) of 1.51 (95% confidence interval [CI], 1.27-1.80). A dose-response effect of elevated BMI on asthma incidence was observed; the OR for incident asthma for normal-weight versus overweight subjects was 1.38 (95% CI, 1.17-1.62) and was further elevated for normal weight versus obesity (OR, 1.92; 95% CI, 1.43-2.59; p<0.0001 for the trend). A similar increase in the OR of incident asthma due to overweight and obesity was observed in men (OR, 1.46; 95% CI, 1.05-2.02) and women (OR, 1.68; 95% CI, 1.45-1.94; p=0.232 for the comparison).

Conclusions: Overweight and obesity are associated with a dose-dependent increase in the odds of incident asthma in men and women, suggesting asthma incidence could be reduced by interventions targeting overweight and obesity.

Figure 1.

Results of systematic literature search.

Figure 2.

Point estimate for the summary odds of incident asthma at 1 year of follow-up, comparing obese and overweight men and women versus normal-weight men and women. Superscript numbers indicate reference number.

Figure 3.

Point estimates for the summary odds of incident asthma at 1 year of follow-up, comparing overweight men and women versus normal-weight men and women (top) and obese men and women versus normal-weight men and women (bottom). Increasing body mass index (BMI) is associated with an increased odds of incident asthma at 1 year of follow-up. Superscript numbers indicate reference number.

Figure 4.

Point estimate for the summary odds of incident asthma at 1 year of follow-up, comparing overweight and obese men versus normal-weight men (top) and overweight and obese women versus normal-weight women (bottom). Superscript numbers indicate reference number.