Incidence of asthma and net change in symptoms in relation to changes in obesity

¹ Dept of Public Health Sciences, King's College London, 5^th Floor Capital House, 42 Weston Street, London SE1 3QD, UK
² Institute of Social and Preventive Medicine, University of Basel, CH 4051 Basel, Switzerland
³ Centre de Recerca en Epidemiologia Ambiental (CREAL-IMIM), Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain
⁴ Institute of Social and Preventive Medicine, University of Basel, CH 4051 Basel, Switzerland; and Division of Pulmonary Medicine, University of Geneva, 1211 Geneva, Switzerland
⁵ INSERM - The French Institute of Health and Medical Research, Unit 700 - Epidemiology, Faculty of Medicine X Bichat, 75018 Paris, France
⁶ University of Verona, Department of Medicine and Public Health, Division of Epidemiology and Statistics, 8-37134 Verona, Italy
⁷ Respiratory Medicine and Allergology, University of Uppsala, 751 85 Uppsala, Sweden
⁸ Respiratory Epidemiology and Public Health Group, Imperial College London, London W2 1PG, UK
⁹ Centre de Recerca en Epidemiologia Ambiental (CREAL-IMIM), Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010, Barcelona, Spain; and Keck School of Medicine, University of Southern California, Los Angeles, California 90089-9013, USA
¹⁰ Dept Thoracic Medicine, 5021 Haukeland Hospital, Bergen, Norway

^* To whom correspondence should be addressed. E-mail: sue.chinn{at}kcl.ac.uk.

	Abstract

The incidence of asthma has been reported to be associated with obesity. An alternative analysis, of net change in prevalence, does not require exclusion of those with asthma at baseline.

Follow-up data were obtained from 9552 participants in the European Community Respiratory Health Survey and the Swiss cohort Study on Air Pollution and Lung Disease in Adults. Incidence of asthma was analysed by proportional hazards regression, and net changes in symptoms and asthma status by generalised estimating equations, by obesity group.

Incidence and net change in ever having had asthma were greater in women than in men, and in participants who remained obese compared to those never obese (hazard ratio 2.00, 95% confidence interval 1.25 to 3.20, excess net change 2.8%, 0.4 to 5.3%, per 10 years). The effect of being obese on net change in diagnosed asthma was greater in women than in men, but for net change in wheeze without a cold it was greater in men.

Our results are consistent with asthma being more frequently diagnosed in women, especially obese women. These findings may help to explain the reports of a stronger association between asthma and obesity in women than in men.

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