Chest
Volume 137, Issue 6, June 2010, Pages 1316-1323
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ORIGINAL RESEARCH
ASTHMA
A Comparison of Obese and Nonobese People With Asthma: Exploring an Asthma-Obesity Interaction

https://doi.org/10.1378/chest.09-2491Get rights and content

Objective

The objectives of our study were to compare patient characteristics and severity of disease in obese and normal-weight-confirmed people with asthma and to explore reasons for misdiagnosis of asthma, including potential interactions with obesity.

Methods

We randomly selected patients with physician-diagnosed asthma from eight Canadian cities. Asthma diagnosis was confirmed via a sequential lung function testing algorithm. Logistic analysis was conducted to compare obese and normal-weight-confirmed people with asthma and to assess characteristics associated with misdiagnosis of asthma. Interaction with obesity was investigated.

Results

Complete assessments were obtained on 496 subjects who reported physician-diagnosed asthma (242 obese and 254 normal-weight subjects); 346 had asthma confirmed with sequential lung testing, and in 150 subjects a diagnosis of asthma was ruled out. Obese subjects with asthma were significantly more likely to be men, have a history of hypertension and gastroesophageal reflux disease, and have a lower FEV1 compared with normal-weight subjects with asthma. Older subjects, men, and subjects with higher FEV1 were more likely to have received misdiagnoses of asthma. Obesity was not an independent predictor of misdiagnosis, however there was an interaction between obesity and urgent visits for respiratory symptoms. The odds ratio for receiving a misdiagnosis of asthma for obese individuals as compared with normal-weight individuals was 4.08 (95% CI, 1.23–13.5) for those with urgent visits in the past 12 months.

Conclusions

Obese people with asthma have lower lung function and more comorbidities compared with normal-weight people with asthma. Obese individuals who make urgent visits for respiratory symptoms are more likely to receive a misdiagnosis of asthma.

Section snippets

Materials and Methods

This is a secondary analysis of a larger study conducted to determine the proportion of Canadian adults who are obese and of normal weight with an incorrect diagnosis of asthma.8 Subjects at least 16 years old who identified themselves as having current, physician-diagnosed asthma were randomly sampled from eight cities across Canada by random-digit dialing. Subjects were included in the study if they were of normal weight (BMI 18–25) or if they were obese (BMI ≥ 30); details of the study

Results

A total of 540 subjects who identified themselves as having physician-diagnosed asthma (266 who were obese and 274 of normal weight) met the eligibility criteria and agreed to participate in the study. Of the 540 participants in the study, 496 (242 who were obese and 254 of normal weight) completed all of the study assessments and could be conclusively evaluated for a diagnosis of asthma. More than 94% of the subjects were of white race. After undergoing rigorous testing to establish the

Discussion

In this study we found that there are differences in randomly selected subjects who were obese and of normal weight who had asthma proven by a diagnostic algorithm. Subjects who had asthma and were obese received a diagnosis at an older age than those who had asthma and were of normal weight. Respiratory symptoms such as dyspnea and wheeze in the past 12 months were more prevalent in patients with asthma who were obese compared with those of normal weight. However, self-reported urgent

Acknowledgments

Author contributions: Dr Pakhale had access to the data and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Dr Pakhale: contributed to the design, implementation, statistical analysis, interpretation, and writing.

Mr Doucette: contributed to the statistical analysis and interpretation.

Ms Vandemheen: contributed to data management, design, implementation, and writing.

Dr Boulet: contributed to the interpretation and writing.

Dr McIvor: contributed to the

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    Funding: This study was funded by the Canadian Institutes of Health Research [Grant MOP-77520] and the Division of Respiratory Medicine, the Ottawa Hospital.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (http://www.chestpubs.org/site/misc/reprints.xhtml).

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