A comparison of obese and nonobese people with asthma: exploring an asthma-obesity interaction.
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 FEV(1) compared with normal-weight subjects with asthma. Older subjects, men, and subjects with higher FEV(1) 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.
MSc, The Ottawa Hospital, 501 Smyth Rd, Ottawa, ON, Canada K1H 8L6. spakhale@ohri.ca
Smita
S
Pakhale
Steve
S
Doucette
Katherine
K
Vandemheen
Louise-Philippe
LP
Boulet
R Andrew
RA
McIvor
J Mark
JM
Fitzgerald
Paul
P
Hernandez
Catherine
C
Lemiere
Sat
S
Sharma
Stephen K
SK
Field
Gonzalo G
GG
Alvarez
Robert E
RE
Dales
Shawn D
SD
Aaron
D000328:Adult; D000367:Age Factors; D000465:Algorithms; D001249:Asthma / Q000150:complications* / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D015992:Body Mass Index; D002170:Canada / Q000453:epidemiology; D016009:Chi-Square Distribution; D005260:Female; D005541:Forced Expiratory Volume; D005764:Gastroesophageal Reflux / Q000150:complications / Q000453:epidemiology; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology; D011788:Quality of Life; D012129:Respiratory Function Tests; D012307:Risk Factors; D012720:Severity of Illness Index