Body mass index, asthma, and respiratory symptoms: a population-based study

Abstract

Objective: To estimate the prevalence of respiratory symptoms and asthma, according to body mass index (BMI), as well as to evaluate factors associated with physician-diagnosed asthma, in individuals ≥ 40 years of age. Methods: This was a population-based cross-sectional study conducted in Florianópolis, Brazil, with probability sampling. Data were collected during home visits. Demographic data were collected, as were reports of physician-diagnosed asthma, respiratory symptoms, medications in use, and comorbidities. Anthropometric measurements were taken. Individuals also underwent spirometry before and after bronchodilator administration. Individuals were categorized as being of normal weight (BMI < 25 kg/m2), overweight (25 kg/m2 ≥ BMI < 30 kg/m2), or obese (BMI ≥ 30 kg/m2). Results: A total of 1,026 individuals were evaluated, 274 (26.7%) were of normal weight, 436 (42.5%) were overweight, and 316 (30.8%) were obese. The prevalence of physician-diagnosed asthma was 11.0%. The prevalence of obesity was higher in women (p = 0.03), as it was in respondents with ≤ 4 years of schooling (p < 0.001) or a family income of 3-10 times the national minimum wage. Physician-diagnosed asthma was more common among obese individuals than among those who were overweight and those of normal weight (16.1%, 9.9%, and 8.0%, respectively; p = 0.04), as were dyspnea (35.5%, 22.5%, and 17.9%, respectively; p < 0.001) and wheezing in the last year (25.6%, 11.9%, and 14.6%, respectively; p < 0.001). These results were independent of patient smoking status. In addition, obese individuals were three times more likely to report physician-diagnosed asthma than were those of normal weight (p = 0.005). Conclusions: A report of physician-diagnosed asthma showed a significant association with being ≥ 40 years of age and with having a BMI ≥ 30 kg/m2. Being obese tripled the chance of physician-diagnosed asthma.

What does the increasing prevalence of obesity mean for the management of asthma and airways disease?

“…This is in line with the findings of a 2007 meta-analysis showing that obesity precedes the development of asthma, nearly doubling the odds of incident asthma. In their study, Souza et al (3) also showed that the prevalence of respiratory symptoms, particularly dyspnea and wheezing, are highest in obese individuals, irrespective of smoking status. Notably, the authors found that, among nonsmokers, chronic expectoration and chronic bronchitis-like symptoms were most common in those who were obese, whereas the prevalence of chronic expectoration did not differ by weight category among current and former smokers.…”

“…In conclusion, the Souza et al study (3) provides important new data regarding the association between obesity and a diagnosis of asthma, as well as the clinical consequences…”

“…Taken together, these findings suggest that, although obesity worsens wheezing and dyspnea, a modest weight loss can effectively reduce those symptoms. Souza et al (3) also found that the prevalence of heart disease and diabetes is higher in obese individuals, who also have the highest incidence of asthma. This is indicative of the increasing burden of chronic disease in the population over 40 years of age and, because heart disease and diabetes are both also associated with increased systemic inflammation, underscores the need to assess and manage systemic and airway inflammation in individuals with asthma.…”

“…The effective management of asthma in obese individuals requires an individualized, multidisciplinary approach, including the assessment and treatment of comorbid disease. Souza et al (3) found that wheezing and dyspnea were both more common in obese individuals. In another study conducted by our group, (11) we demonstrated that a 5-10% weight loss is effective for improving asthma control (including symptoms of wheezing and dyspnea), as well as lung function and asthma-related quality of life, in overweight and obese adults with asthma.…”

“…In a study published in this issue of the JBP, Souza et al (3) examined the prevalence of respiratory symptoms and asthma according to body mass index, as well as evaluating the factors associated with asthma in more than 1,000 adults 40 years of age or older. Their study was a cross-sectional subanalysis of the Respira Floripa study, in which the study population was derived from a metropolitan area in Brazil.…”