Effect of retention time on NMP22 bladder check assay results in voided urine

Background: Bladder cancer health care costs are high, primarily due to the need for long-term follow-up. Several markers have been developed to detect the presence of urothelial cell carcinoma (UCC) in the urinary tract. These markers have differing sensitivity and specificity. The nuclear matrix protein-22 (NMP22) test increases the ability to detect recurrent bladder cancer. Objectives: The aim of this study was to evaluate possible changes in the results of this test depending on the length of the retention time in the bladder of the collected urine. Patients and Methods: Between January and June 2006 we prospectively evaluated voided urine specimens in 69 patients undergoing control cystoscopy or transurethral resection of primary or recurrent bladder cancer. We tested for NMP22 in the first morning urine sample and samples collected after 5 min, 30 min and 2 h of urine retention in the bladder. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were determined, and results were grouped according to tumor stage and grade. Results: Global sensitivity was similar in all groups (first morning sample and 5-min, 30-min and 2-h urine retention); the best sensitivity was observed at the 30-min sample point (80%). Specificity varied from 75% to 100% and the best results were obtained in first morning urine and at 30 min and 2 h. PPV was 95.5–100% at the different urine retention periods, while NPV was in the range of 27.3–33.3%. Conclusion: Although this was not a large series, it appears that there is a tendency towards better results with the 30-min urine retention time. It is not necessary to wait 2 h for test operability.