title: Caffeine consumption and exacerbations of chronic obstructive pulmonary disease: retrospective study.
abstract: BACKGROUND
  The modulation of adenosine receptors has been proposed as new therapeutic target for chronic obstructive pulmonary disease, but studies in humans were negative. Caffeine is widely consumed and acts by non-selective modulation of these receptors, allowing for a non-interventional evaluation of the purinergic effects on COPD. We evaluated the effects of chronic caffeine consumption on the risk for COPD exacerbations.
  
  
  METHODS
  Retrospective study including patients with COPD. The total number of exacerbations during a three-year period and the mean daily caffeine consumption in the last twenty years were evaluated. A univariate and multiple regression analysis were performed for evaluation of the significant predictors of exacerbations.
  
  
  RESULTS
  A total of 90 patients were included. Most were males (82.2%) and had a mean forced expiratory volume in the first second (FEV1) of 57.0±17.1% predicted. The mean daily caffeine consumption was 149.7±140.9mg. There was no correlation between the mean caffeine consumption and exacerbations (p>0.05).
  
  
  CONCLUSIONS
  Our results suggest that caffeine has no significant effect on the frequency of COPD exacerbations. These conclusions are limited by the sample size and the retrospective nature of the study.
authors.affiliation: Centre of Pneumology, Faculty of Medicine, University of Coimbra, Portugal. Electronic address: pedro_miguel_oliv_lopes@hotmail.com.
authors.forename: P O
authors.initials: PO
authors.lastname: Lopes
authors.affiliation: Centre of Pneumology, Faculty of Medicine, University of Coimbra, Portugal; Unit of Pneumology, Centro Hospitalar e Universitário de Coimbra, Portugal; CNC - Center for Neurosciences and Cell Biology, University of Coimbra, Portugal. Electronic address: alfarotm@gmail.com.
authors.forename: T M
authors.initials: TM
authors.lastname: Alfaro
authors.affiliation: Unit of Pneumology, Centro Hospitalar e Universitário de Coimbra, Portugal. Electronic address: plopeshuc@hotmail.com.
authors.forename: P
authors.initials: P
authors.lastname: Lopes
authors.affiliation: Unit of Pneumology, Centro Hospitalar e Universitário de Coimbra, Portugal; FMUC - Faculty of Medicine, University of Coimbra, Portugal. Electronic address: cunharod@gmail.com.
authors.forename: R A
authors.initials: RA
authors.lastname: Cunha
authors.affiliation: Centre of Pneumology, Faculty of Medicine, University of Coimbra, Portugal; Unit of Pneumology, Centro Hospitalar e Universitário de Coimbra, Portugal. Electronic address: Carlos.crobalo@gmail.com.
authors.forename: C Robalo
authors.initials: CR
authors.lastname: Cordeiro
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002110:Caffeine / Q000009:adverse effects*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000139:chemically induced*; D012189:Retrospective Studies; D018570:Risk Assessment
chemical_list: D002110:Caffeine
keywords: COPD; Caffeine; Coffee; Disease exacerbation; Pharmacology; Purines; Respiratory Tract Diseases