The association between body mass index (BMI) and asthma

Background: In 2004, we published an evidence based and consented guideline on primary and secondary prevention of asthma, allergic rhinitis and atopic eczema. In order to update this guideline, we repeated a systematic literature search in 2008. Methods: A literature search was performed in Medline for the years 2003 through May 2008. The used mesh-term groups were as follows. Endpoints: asthma, allergy, allergic, atopic, hay fever, dermatitis, eczema, rhinitis; interventions: prevention, risk factor, epidemiology; study types: randomized controlled trial, clinical trial, control study, systematic review, meta-analysis, case-control study, cohort study. We included studies on humans published in English or German language and excluded therapeutic and drug trials. Results: We obtained 4,556 hits of which 217 potentially relevant studies were identified. For the association between BMI and asthma we identified three reviews, eleven cohort studies, and one case control study. Ten studies (two reviews, seven cohort studies, and one case-control study) showed that overweight (BMI 24) and obesity (BMI 30) were risk factors for asthma. Conclusion: By this literature search it is possible to update the current evidence-based recommendation on allergy prevention and to adapt the recommendations according to the current literature.