title: Asthma-associated comorbidities in children with and without secondhand smoke exposure.
abstract: BACKGROUND
  Secondhand smoke (SHS) exposure is known to trigger asthma, but asthma disease severity and comorbidities in children exposed to SHS are not very well quantified.
  
  
  OBJECTIVE
  To identify comorbidities and understand health care usage in children with asthma exposed to SHS (cases) compared with children with asthma but without SHS exposure (controls).
  
  
  METHODS
  A retrospective nested matched case-and-control study was conducted with children 5 to 18 years old who were enrolled in the Pediatric Asthma Management Program. Pulmonary function testing (spirometry, methacholine challenges, and exhaled nitric oxide) and body mass index were reviewed. Influenza vaccination rates, oral steroid usage, emergency department visits, and hospitalizations were assessed. Network analysis of the 2 groups also was conducted to evaluate for any associations between the variables.
  
  
  RESULTS
  Cases had significantly higher body mass index percentiles (>75%, odds ratio [OR] 1.64, 95% confidence interval [CI] 1.22-2.2, P = .001). Cases were less likely to have had a methacholine challenge (OR 0.49, 95% CI 0.36-0.68, P < .001) and an exhaled nitric oxide (OR 0.6, 95% CI 0.37-0.97, P = .04) performed than controls. The ratio of forced expiration volume in 1 second to forced vital capacity and forced expiration volume in 1 second were lower in cases than in controls (P < .05). Cases were less likely to have received an influenza vaccination (OR 0.61, 95% CI 0.45-0.82, P = .001) than controls. Unsupervised multivariable network analysis suggested a lack of discrete and unique subgroups between cases and controls.
  
  
  CONCLUSIONS
  Children with asthma exposed to SHS are more likely to have comorbid conditions such as obesity, more severe asthma, and less health care usage than those not exposed to SHS. Smoking cessation interventions and addressing health disparities could be crucial in this vulnerable population.
authors.affiliation: Division of Allergic Diseases, Mayo Clinic, Rochester, Minnesota.
authors.forename: Regan C
authors.initials: RC
authors.lastname: Pyle
authors.affiliation: Division of Allergic Diseases, Mayo Clinic, Rochester, Minnesota.
authors.forename: Rohit
authors.initials: R
authors.lastname: Divekar
authors.affiliation: Division of Allergic Diseases, Mayo Clinic, Rochester, Minnesota.
authors.forename: Sara M
authors.initials: SM
authors.lastname: May
authors.affiliation: Mayo Medical School, Mayo Clinic, Rochester, Minnesota.
authors.forename: Nirmala
authors.initials: N
authors.lastname: Narla
authors.affiliation: Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota.
authors.forename: Paolo T
authors.initials: PT
authors.lastname: Pianosi
authors.affiliation: Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota.
authors.forename: Martha F
authors.initials: MF
authors.lastname: Hartz
authors.affiliation: Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota.
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Ott
authors.affiliation: Division of Allergic Diseases, Mayo Clinic, Rochester, Minnesota.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Park
authors.affiliation: Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota.
authors.forename: Deborah B
authors.initials: DB
authors.lastname: McWilliams
authors.affiliation: Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota.
authors.forename: Joy A
authors.initials: JA
authors.lastname: Green
authors.affiliation: Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota.
authors.forename: Krista N
authors.initials: KN
authors.lastname: Despins
authors.affiliation: Division of Allergic Diseases, Mayo Clinic, Rochester, Minnesota; Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota. Electronic address: joshi.avni@mayo.edu.
authors.forename: Avni Y
authors.initials: AY
authors.lastname: Joshi
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000453:epidemiology*; D015992:Body Mass Index; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D045853:Exhalation; D005260:Female; D005541:Forced Expiratory Volume; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007252:Influenza Vaccines; D019570:Inhalation Exposure; D008297:Male; D016210:Methacholine Chloride; D009569:Nitric Oxide / Q000378:metabolism; D009765:Obesity / Q000453:epidemiology; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D013147:Spirometry; D014028:Tobacco Smoke Pollution; D014611:Vaccination / Q000706:statistics & numerical data
chemical_list: D007252:Influenza Vaccines; D014028:Tobacco Smoke Pollution; D016210:Methacholine Chloride; D009569:Nitric Oxide