Chest
Volume 122, Issue 4, October 2002, Pages 1256-1263
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Clinical Investigations
The Relation of Body Mass Index to Asthma, Chronic Bronchitis, and Emphysema

https://doi.org/10.1378/chest.122.4.1256Get rights and content

Background

Recent studies have suggested a relationship between asthma and obesity. Despite these reports, the effect of being underweight or overweight as a risk factor for airway obstructive diseases (AODs) is not clear.

Objectives

To determine whether a relation of body mass index (BMI) to asthma, chronic bronchitis (CB), or emphysema exists (analysis 1), and, if so, whether the association between obesity and asthma is modified by gender (analysis 2).

Design

Nested case-control study from the longitudinal cohort of the Tucson Epidemiologic Study of Airways Obstructive Diseases.

Patients

Analysis 1: physician-confirmed incident cases of asthma (n = 102), CB (n = 299), or emphysema (n = 72) who denied any prior AODs. Analysis 2: all 169 incident cases of asthma, regardless of any previous AODs, stratified by gender and by other potential effect modifiers. In both analyses, we selected only subjects at least 20 years old who had weight and height measured during the study.

Measurements

BMI and other risk factors were assessed prior to the onset of the AOD (cases) or prior to the last completed survey (control subjects).

Results

A diagnosis of emphysema was significantly associated with a BMI < 18.5 (odds ratio [OR], 2.97; 95% confidence interval [CI], 1.33 to 6.68, when compared to healthy control subjects). A BMI ≥ 28 increased the risk of receiving a diagnosis of asthma (OR, 2.10; 95% CI, 1.31 to 3.36) and CB (OR, 1.80; 95% CI, 1.32 to 2.46). About 30% of the patients with asthma and 25% of the patients with CB (vs 16% of the control subjects, p < 0.001) were preobese or obese, regardless whether BMI was assessed before the diagnosis or before the onset of respiratory symptoms. The relation of elevated BMI to asthma was significant only among women.

Conclusions

Patients with emphysema are more likely to be underweight, and patients with CB are more likely to be obese. However, the temporal relationship between abnormal BMI and the onset of COPD is uncertain. Preobese and obese women are at increased risk of acquiring asthma. This relation, particularly if it is causal, has potentially relevant public health implications.

Section snippets

Materials and Methods

We used data that were collected as part of the Tucson Epidemiologic Study of Airways Obstructive Diseases, a prospective cohort study on a stratified cluster sample of white non-Mexican American households enrolled between March 1972 and April 1973. Details of the enrollment process and interview techniques have been previously reported.10 Briefly, square blocks in the Tucson area were stratified based on the age of the head of the household, ethnic group, and socioeconomic status, and

Analysis 1

In Table 1, each of the AOD groups is compared to the control group. Unlike the asthma and CB groups, the proportion of male subjects in the emphysema group was significantly higher than in the control group. As expected, asthmatics were more likely to be atopic and had higher total IgE levels than control subjects. Patients with CB and patients with emphysema also had higher levels of total IgE than control subjects, but their geometric means were lower than those of patients with asthma, and

Discussion

There is an increasing interest in the relationship between obesity and asthma; however, there is a lack of prospective studies on the issue. By using a large longitudinal cohort, we were able to confirm the association between obesity and asthma. We found, in fact, that subjects with a BMI ≥ 28 had an increased risk of acquiring asthma. The potential confounding effect of COPD on this association was addressed by excluding asthmatic patients with other previous AOD in analysis 1 and by

ACKNOWLEDGMENT

The authors thank Margaret Kurzius-Spencer, MS, MPH, for her comments and suggestions.

References (28)

  • SO Shaheen et al.

    Birth weight, body mass index and asthma in young adults

    Thorax

    (1999)
  • LM Schachter et al.

    Obesity is a risk for asthma and wheeze but not airway hyperresponsiveness

    Thorax

    (2001)
  • SY Young et al.

    Body mass index and asthma in the military population of the northwestern United States

    Arch Intern Med

    (2001)
  • CA Camargo et al.

    Prospective study of body mass index, weight change, and risk of adult-onset asthma in women

    Arch Intern Med

    (1999)
  • Cited by (0)

    At the time of the study, Dr. Guerra was a fellow from the Institute of Respiratory Diseases, IRCCS Policlinico Hospital, University of Milan, Italy.

    Drs. Guerra, Sherrill, and Martinez were funded by grant No. HL 56177 from the National Heart, Lung, and Blood Institute.

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