Does the relationship between asthma and obesity differ by neighborhood?

Overview

BACKGROUND: Prior studies suggest that obesity may cause asthma. Obesity and asthma are prevalent in low-income urban neighborhoods, but the impact of obesity on asthma in such neighborhoods has not been examined. METHODS: The New York City Department of Health and Mental Hygiene surveyed 6119 adults age 18-54 years in 2002. Obesity was defined as body mass index > or = 30 kg/m(2) and current asthma as physician diagnosed asthma plus recent symptoms. We calculated prevalence (risk) differences (RD) and population attributable risk percents (PAR%). RESULTS: Obese individuals had a 2.0% (95% CI: 0.5%, 3.6%; p=0.01) higher risk of current asthma than normal weight individuals overall. Obesity was more common in low-income neighborhoods compared with middle-to-upper-income neighborhoods (23% vs. 14%, p<0.001), as was current asthma (6% vs. 4%, respectively, p=0.02). The risk of current asthma associated with obesity was similar in low-income (RD: 1.3%, 95% CI: -1.5%, 4.0%; p=0.36) and middle-to-upper-income neighborhoods (RD: 2.0%, 95% CI: 0.1%, 3.9%; p=0.04). The PAR% for asthma due to obesity was not greater in low-income (7.3%) than in middle-to-upper-income neighborhoods (7.7%). CONCLUSIONS: It is unlikely that the excess asthma prevalence in urban low-income neighborhoods is disproportionately attributable to obesity. Instead, alternative causes of excess asthma should be sought.