title: Smoking Status Confirmation by Proxy: Validation in a Smoking Cessation Trial.
abstract: BACKGROUND
  Biochemical confirmation (BC) of self-report is the gold standard of evidence for abstinence in smoking cessation research, but difficulty in obtaining samples may bias estimates of quit rates. Proxy confirmation (PC) has not been validated in cessation trials. We assessed the feasibility and validity of PC in a cessation trial for hospitalized smokers.
  
  
  METHODS
  We enrolled 402 daily cigarette smokers during a hospital admission. At enrollment, participants provided demographics, smoking history, and named proxies to confirm their smoking status at follow-up. Participants provided self-reported (SR) 7-day tobacco abstinence by telephone at 6 months post-discharge. SR quitters were asked to mail a saliva sample for BC. Incentives were offered for survey completion ($20) and returned samples ($50). We called proxies for all those with SR to obtain PC. Quit rates were calculated with missing data indicating smoking. We assessed associations of nonresponse with baseline characteristics using chi-squared tests and logistic regression. We calculated the sensitivity and specificity of PC in detecting smokers as determined by BC.
  
  
  RESULTS
  All patients named at least one proxy. Response rates were 82% for SR, 84% for PC, and 69% for BC. Observed participant characteristics were unrelated to provision of sample for BC. Estimated quit rates were 35% for SR, 27% for SR + PC, 21% for SR + BC and 27% for SR + BC or PC. Sensitivity of PC was not higher than SR (73% vs. 77%); specificity was lower (84% vs. 100%).
  
  
  CONCLUSIONS
  PC was feasible but not superior to self-report in a cessation trial.
authors.affiliation: Tobacco Research and Treatment Center, Massachusetts General Hospital, Boston, MA; Department of Medicine, Harvard Medical School, Boston, MA; sregan@partners.org.
authors.forename: Susan
authors.initials: S
authors.lastname: Regan
authors.affiliation: Tobacco Research and Treatment Center, Massachusetts General Hospital, Boston, MA;
authors.forename: Zachary Z
authors.initials: ZZ
authors.lastname: Reid
authors.affiliation: Tobacco Research and Treatment Center, Massachusetts General Hospital, Boston, MA; Mongan Institute for Health Policy, Massachusetts General Hospital, Boston, MA;
authors.forename: Jennifer H K
authors.initials: JH
authors.lastname: Kelley
authors.affiliation: Tobacco Research and Treatment Center, Massachusetts General Hospital, Boston, MA;
authors.forename: Michele
authors.initials: M
authors.lastname: Reyen
authors.affiliation: Tobacco Research and Treatment Center, Massachusetts General Hospital, Boston, MA; Mongan Institute for Health Policy, Massachusetts General Hospital, Boston, MA;
authors.forename: Molly
authors.initials: M
authors.lastname: Korotkin
authors.affiliation: Tobacco Research and Treatment Center, Massachusetts General Hospital, Boston, MA; National Center for PTSD, VA Boston Healthcare System, Boston, MA;
authors.forename: Sandra J
authors.initials: SJ
authors.lastname: Japuntich
authors.affiliation: Tobacco Research and Treatment Center, Massachusetts General Hospital, Boston, MA; Department of Health Policy and Management, University of California, Los Angeles, CA.
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Viana
authors.affiliation: Tobacco Research and Treatment Center, Massachusetts General Hospital, Boston, MA; Department of Medicine, Harvard Medical School, Boston, MA; Mongan Institute for Health Policy, Massachusetts General Hospital, Boston, MA;
authors.forename: Douglas E
authors.initials: DE
authors.lastname: Levy
authors.affiliation: Tobacco Research and Treatment Center, Massachusetts General Hospital, Boston, MA; Department of Medicine, Harvard Medical School, Boston, MA; Mongan Institute for Health Policy, Massachusetts General Hospital, Boston, MA;
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Rigotti
mesh_terms: D003367:Cotinine / Q000032:analysis; D005260:Female; D006760:Hospitalization; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009042:Motivation; D010351:Patient Discharge; D015203:Reproducibility of Results; D027544:Salvia / Q000737:chemistry*; D057566:Self Report; D016540:Smoking Cessation / Q000706:statistics & numerical data*; D000074606:Smoking Prevention; D013689:Telephone; D014029:Tobacco Use Disorder / Q000517:prevention & control*
chemical_list: D003367:Cotinine
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