title: The accuracy of urinary cotinine immunoassay test strip as an add-on test to self-reported smoking before major elective surgery.
abstract: BACKGROUND
  Smoking is a preventable cause of perioperative complications. An accurate and rapid classification of smoking status is essential as up to 35% of smokers deny smoking before surgery. We compared the diagnostic performance of a preoperative urinary cotinine immunoassay test strip (NicAlert®) as an add-on test to patient's self-reported smoking status.
  
  
  METHODS
  Four hundred and sixty-five patients undergoing major elective surgery self-reported their smoking history and provided a sample for measuring urinary cotinine concentration by liquid chromatography tandem mass spectrometry (reference standard) and NicAlert®. Using the "either test positive" rule, the gain in diagnostic performance for NicAlert® add-on test was assessed using relative positive and negative likelihood ratios (LRs) and area under the receiver operating characteristic curve (AUROC) with 95% CIs.
  
  
  RESULTS
  Of the 60 patients with a positive reference standard (adjusted cotinine ≥ 50 ng/ml), 10 (16.7%) denied current cigarette smoking. The NicAlert® add-on test had better test performance measures (sensitivity = 95.0%, specificity = 94.8%) than self-reported smoking history alone (sensitivity = 83.3%, specificity = 95.0%). The relative positive and negative LRs were 1.09 (95% CI = 0.95-1.24) and 0.30 (95% CI = 0.12-0.78), respectively. The AUROC for the NicAlert® add-on test (0.90; 95% CI = 0.84-0.96) was significantly higher than for the self-reported smoking history alone (0.78; 95% CI = 0.69-0.88) (p = .006).
  
  
  CONCLUSIONS
  The NicAlert® add-on test strategy had excellent diagnostic test performance for identifying current smokers who are expected to have a high risk of perioperative complications.
authors.affiliation: Department of Anaesthesia and Intensive Care, Chinese University of Hong Kong, Shatin, NT, Hong Kong.
authors.forename: Anna
authors.initials: A
authors.lastname: Lee
authors.forename: Tony
authors.initials: T
authors.lastname: Gin
authors.forename: Po Tong
authors.initials: PT
authors.lastname: Chui
authors.forename: Perpetua E
authors.initials: PE
authors.lastname: Tan
authors.forename: Chun Hung
authors.initials: CH
authors.lastname: Chiu
authors.forename: Tsui Ping
authors.initials: TP
authors.lastname: Tam
authors.forename: Winnie
authors.initials: W
authors.lastname: Samy
mesh_terms: D000368:Aged; D003367:Cotinine / Q000652:urine*; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D008297:Male; D008875:Middle Aged; D057566:Self Report; D012907:Smoking / Q000652:urine*; D014029:Tobacco Use Disorder / Q000652:urine
chemical_list: D003367:Cotinine