title: Overweight and obesity may lead to under-diagnosis of airflow limitation: findings from the Copenhagen City Heart Study.
abstract: BACKGROUND
  The prevalence of obesity has increased during the last decades and varies from 10-20% in most European countries to approximately 32% in the United States. However, data on how obesity affects the presence of airflow limitation (AFL) defined as a reduced ratio between forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) are scarce.
  
  
  METHODS
  Data was derived from the third examination of the Copenhagen City Heart Study from 1991 until 1994 (n = 10,135). We examine the impact of different adiposity markers (weight, body mass index (BMI), waist circumference, waist-hip ratio, and abdominal height) on AFL. AFL was defined in four ways: FEV1/FVC ratio < 0.70, FEV1/FVC ratio < lower limit of normal (LLN), FEV1/FVC ratio <0.70 including at least one respiratory symptom, and FEV1/FVC ratio < LLN and FEV1% of predicted < LLN.
  
  
  RESULTS
  All adiposity markers were positively and significantly associated with FEV1/FVC independent of age, sex, height, smoking status, and cumulative tobacco consumption. Among all adiposity markers, BMI was the strongest predictor of FEV1/FVC. FEV1/FVC increased with 0.04 in men and 0.03 in women, as BMI increased with 10 units (kg · m-2). Consequently, diagnosis of AFL was significantly less likely in subjects with BMI ≥ 25 kg · m-2 with odds ratios 0.63 or less compared to subjects with BMI between 18.5-24.9 kg · m-2 when AFL was defined as FEV1/FVC < 0.70.
  
  
  CONCLUSIONS
  High BMI reduces the probability of AFL. Ultimately, this may result in under-diagnosis and under-treatment of COPD among individuals with overweight and obesity.
authors.affiliation: 1Department of Internal Medicine, Section of Respiratory Medicine, Herlev Hospital, Copenhagen University Hospital , Copenhagen, Denmark.
authors.forename: Yunus
authors.initials: Y
authors.lastname: Çolak
authors.forename: Jacob Louis
authors.initials: JL
authors.lastname: Marott
authors.forename: Jørgen
authors.initials: J
authors.lastname: Vestbo
authors.forename: Peter
authors.initials: P
authors.lastname: Lange
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D003718:Denmark; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology; D050177:Overweight / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000209:etiology; D012307:Risk Factors; D014797:Vital Capacity
keywords: airflow limitation; airway obstruction; body mass index; chronic obstructive pulmonary disease; diagnosis; epidemiology; lower limit of normal; lung function; obesity; spirometry