title: Acetaminophen use and the risk of asthma in children and adults: a systematic review and metaanalysis.
abstract: BACKGROUND
  Epidemiologic studies have identified an increased risk of asthma with acetaminophen use, but the results have been conflicting. We sought to quantify the association between acetaminophen use and the risk of asthma in children and adults.
  
  
  METHODS
  We searched all the major medical databases, including MEDLINE (from 1966 to 2008) and EMBASE (from 1980 to 2008) to identify pertinent articles. All clinical trials and observational studies were considered. For observational studies, we selected those that clearly defined acetaminophen use and asthma diagnosis. Study quality was assessed by two reviewers, and data were extracted into a spreadsheet. A random-effects model was used to combine studies with asthma and wheezing among both children and adults.
  
  
  RESULTS
  Thirteen cross-sectional studies, four cohort studies, and two case-control studies comprising 425,140 subjects were included in the review. The pooled odds ratio (OR) for asthma among subjects using acetaminophen was 1.63 (95% CI, 1.46 to 1.77). The risk of asthma in children among users of acetaminophen in the year prior to asthma diagnosis and within the first year of life was elevated (OR: 1.60 [95% CI, 1.48 to 1.74] and 1.47 [95% CI, 1.36 to 1.56], respectively). Only one study reported the association between high acetaminophen dose and asthma in children (OR, 3.23; 95% CI, 2.9 to 3.6). There was an increase in the risk of asthma and wheezing with prenatal use of acetaminophen (OR: 1.28 [95% CI, 1.16 to 41] and 1.50 [95% CI, 1.10 to 2.05], respectively).
  
  
  CONCLUSIONS
  The results of our review are consistent with an increase in the risk of asthma and wheezing in both children and adults exposed to acetaminophen. Future studies are needed to confirm these results.
authors.affiliation: Pharmacoepidemiology Unit, Center for Clinical Epidemiology and Evaluation, Vancouver Coastal Health Research Institute, Vancouver, BC, Canada; Department of Medicine, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Mahyar
authors.initials: M
authors.lastname: Etminan
authors.affiliation: Collaboration for Outcome Research and Evaluation, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Sadatsafavi
authors.affiliation: School of Public Health Sciences, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Siavash
authors.initials: S
authors.lastname: Jafari
authors.affiliation: Pharmacoepidemiology Unit, Center for Clinical Epidemiology and Evaluation, Vancouver Coastal Health Research Institute, Vancouver, BC, Canada.
authors.forename: Mimi
authors.initials: M
authors.lastname: Doyle-Waters
authors.affiliation: Faculty of Dentistry, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Kevin
authors.initials: K
authors.lastname: Aminzadeh
authors.affiliation: The Lung Center, Vancouver Coastal Health Research Institute, Vancouver, BC, Canada; Division of Respiratory Medicine, University of British Columbia, Vancouver, BC, Canada; Pharmacoepidemiology Unit, Center for Clinical Epidemiology and Evaluation, Vancouver Coastal Health Research Institute, Vancouver, BC, Canada. Electronic address: markf@interchange.ubc.ca.
authors.forename: J Mark
authors.initials: JM
authors.lastname: FitzGerald
mesh_terms: D000082:Acetaminophen / Q000009:adverse effects* / Q000627:therapeutic use*; D000328:Adult; D000975:Antioxidants / Q000378:metabolism; D001249:Asthma / Q000139:chemically induced / Q000453:epidemiology*; D002648:Child; D006801:Humans; D015201:Meta-Analysis as Topic
chemical_list: D000975:Antioxidants; D000082:Acetaminophen