title: Sensitivity analysis of the diagnostic value of endoscopies in cross-sectional studies in the absence of a gold standard.
abstract: OBJECTIVE
  The evaluation of the diagnostic value of endoscopic procedures usually lacks a gold standard when performed in cross-sectional studies. The objective is to demonstrate an easily applicable method to assess the possible range of sensitivity, specificity, and predictive values of endoscopic procedures in the absence of a gold standard method.
  
  
  METHODS
  Data from a study of 328 endoscopies comparing two different methods to diagnose superficial bladder cancer were used as a numerical example. Both endoscopic procedures were performed in the same patients in one session. Under the assumption of a systematic misclassification process, a model to correct sensitivity estimates is developed.
  
  
  RESULTS
  The lowest possible sensitivity estimate for a new fluorescence endoscopy technique (FE) was 78%, the maximum 97.5%. Depending on realistic assumptions made upon the misclassification, a reasonable estimate for sensitivity was 93.4% (95% confidence interval [CI]: 90%-97.3%) for the FE technique. The sensitivity of the traditional white-light endoscopy method ranged from 47.2% to 53%, with a reasonable estimate of 46.7% (95% CI: 39.4%-54.3%).
  
  
  CONCLUSIONS
  This method to determine the theoretically possible range of sensitivity estimates in endoscopic procedures is helpful in cross-sectional studies with a missing gold standard method. It is easily applicable for a variety of endoscopic procedures, including upper and lower gastro-intestinal tract, urogenital tract, or diagnostic laparoscopic surgery.
authors.affiliation: Harvard Medical School, USA. schneeweiss@post.harvard.edu
authors.forename: S
authors.initials: S
authors.lastname: Schneeweiss
mesh_terms: D000622:Aminolevulinic Acid; D003430:Cross-Sectional Studies; D003558:Cystoscopy / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D001749:Urinary Bladder Neoplasms / Q000175:diagnosis*
chemical_list: D000622:Aminolevulinic Acid