Sensitivity analysis of the diagnostic value of endoscopies in cross-sectional studies in the absence of a gold standard

Objectives: The evaluation of the diagnostic value of endoscopic procedures usually lacks a gold standard when performed in cross-sectional studies. T he objective is to demonstrate an easily applicable method to assess the po ssible range of sensitivity, specificity, and predictive values of endoscop ic procedures in the absence of a gold standard method. Methods: Data from a study of 328 endoscopies comparing two different metho ds to diagnose superficial bladder cancer were used as a numerical example. Both endoscopic procedures were performed in the same patients in one sess ion. Under the assumption of a systematic misclassification process, a mode l to correct sensitivity estimates is developed. Results: The lowest possible sensitivity estimate for a new fluorescence en doscopy technique (FE) was 78%, the maximum 97.5%. Depending on realistic a ssumptions made upon the misclassification, a reasonable estimate for sensi tivity was 93.4% (95% confidence interval [CI]: 90%-97.3%) for the FE techn ique. The sensitivity of the traditional white-light endoscopy method range d 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 s ensitivity 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-intesti nal tract, urogenital tract, or diagnostic laparoscopic surgery.