SENSITIVITY ANALYSIS OF THE DIAGNOSTIC VALUE OF ENDOSCOPIES IN CROSS-SECTIONAL STUDIES IN THE ABSENCE OF A GOLD STANDARD

Abstract

Objectives: 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.