Higher BMI ‘not linked to worse asthma control’
MedWire News: Results of a US study suggest that a higher body mass index (BMI) is not associated with poorer asthma control, indicating that weight loss may not improve asthma control in obese patients.
Writing in the Journal of Allergy and Clinical Immunology, Gregory Diette (Johns Hopkins University, Baltimore, USA) and team explain: “Epidemiologic studies looking at the relationship between obesity and asthma have found increasing BMI to be associated with increased asthma incidence.”
However, they add: “Whether this association is coincidental or a result of a true physiologic link remains unclear. To date, studies looking at the association of obesity and cardinal features of asthma pathophysiology, such as hyperresponsiveness and airflow limitation, have yielded conflicting results.”
To investigate further, the researchers studied the relationship between BMI and asthma control among 292 people with asthma from an ethnically diverse urban community with a high prevalence of obesity. The average age of the participants was 47 years, 82% were women and 67% were African American.
All the participants completed four validated asthma control questionnaires: the Asthma Control and Communication Instrument (ACCI), the Asthma Control Test (ACT), the Asthma Control Questionnaire (ACQ), and the Asthma Therapy Assessment Questionnaire (ATAQ).
Overall, 63% of the participants were obese (BMI ≥30 kg/m2), 22% were overweight (BMI 25–29.9 kg/m2), and just 15% were of normal weight (18.5–24.9 kg/m2).
Scores on the four questionnaires indicated that, on average, the participants had suboptimal asthma control, at an average score of 8.3 out of 19 on the ACCI, 15.4 out of 25 on the ACT, 2.1 out of 6 on the ACQ, and 1.3 out of 4 on the ATAQ.
Overall, 96% of the cohort met criteria for suboptimal control on at least one of the questionnaires.
Regression analysis revealed no significant association between BMI and asthma control using any of the four control questionnaires. This finding remained true after accounting for age, gender, race, insurance status, smoking status, FEV1, various comorbid illnesses, and long-term use of asthma controller medications.
Diette and team conclude: “In the current study, conducted in an urban population cared for in a primary care setting, obesity was not associated with worse asthma control. Obese patients had asthma control that was similar to that of the nonobese, and even among those who were obese, there was no tendency toward worse control with greater degrees of obesity.”
They add: “Although there are many health benefits associated with weight loss, findings from the current study do not suggest that weight loss would result in improved asthma control.”
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By Mark Cowen