title: Body mass index is a stronger predictor than the metabolic syndrome for future asthma in women. The longitudinal CARDIA study.
abstract: BACKGROUND
  It is hypothesized that the metabolic syndrome explains the association between body mass index (BMI) and asthma in adults.
  
  
  OBJECTIVE
  Our objective was to longitudinally compare the relative strengths of the associations of the metabolic syndrome and BMI with incident asthma in adults.
  
  
  METHODS
  We included 4,619 eligible participants in the Coronary Artery Risk Development in Young Adults (CARDIA) cohort followed over 25 years. Incident asthma was defined by a new self-reported provider asthma diagnosis plus either the presence of asthma symptoms and/or use of asthma medications. Cox proportional hazard analyses were performed.
  
  
  RESULTS
  Six hundred two subjects (417 women and 185 men) developed incident asthma over 25 years of follow-up. Metabolic syndrome predicted incident asthma among women but not men (unadjusted hazard ratios, 1.50 and 0.98; P = 0.01 and 0.93, respectively). BMI had a similar predictive association among women but not men (unadjusted hazard ratios, 1.19 and 1.04 per 5 units of BMI; P < 0.001 and 0.60, respectively). The association of metabolic syndrome with incident asthma in women was no longer statistically significant after adjustment for BMI (P = 0.44). In contrast, the association of BMI with incident asthma in women remained statistically significant after adjusting for the metabolic syndrome (P = 0.01). In a stepwise model, BMI was a stronger predictor than the metabolic syndrome (P = 0.001).
  
  
  CONCLUSIONS
  BMI is a stronger predictor of incident asthma among women than the metabolic syndrome. Other obesity-associated factors that are not a part of the metabolic syndrome may play a role in the BMI-asthma association in women.
authors.affiliation: Department of Medicine, University of New Mexico Health Sciences Center School of Medicine, Albuquerque, NM 87131, USA.
authors.forename: Nour
authors.initials: N
authors.lastname: Assad
authors.forename: Clifford
authors.initials: C
authors.lastname: Qualls
authors.forename: Lewis J
authors.initials: LJ
authors.lastname: Smith
authors.forename: Alex
authors.initials: A
authors.lastname: Arynchyn
authors.forename: Bharat
authors.initials: B
authors.lastname: Thyagarajan
authors.forename: Mark
authors.initials: M
authors.lastname: Schuyler
authors.forename: David R
authors.initials: DR
authors.lastname: Jacobs
authors.forename: Akshay
authors.initials: A
authors.lastname: Sood
mesh_terms: D000328:Adult; D001249:Asthma / Q000453:epidemiology* / Q000209:etiology; D015992:Body Mass Index; D005260:Female; D005500:Follow-Up Studies; D005544:Forecasting; D006801:Humans; D015994:Incidence; D008297:Male; D024821:Metabolic Syndrome / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D014481:United States / Q000453:epidemiology; D055815:Young Adult
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