Objectives

To evaluate the clinical utility of the urinary bladder cancer antigen UBC® Rapid Test for the diagnosis of bladder cancer (BC) and to develop and validate nomograms to identify patients at high-risk of primary BC.

Patients and methods

Data from 1,787 patients from 13 participating centers tested between 2012 and 2020, including 763 patients with BC, were analyzed. Urine samples were analyzed with the UBC® Rapid Test. The nomograms were developed using data from 320 patients and externally validated using data from 274 patients. The diagnostic accuracy of the UBC® Rapid Test was evaluated using receiver operating characteristics analysis. Brier scores and calibration curves were chosen for validation. Biopsy-proven BC was predicted using multivariate logistic regression.

Results

The sensitivity, specificity, and area under the curve for the UBC® Rapid Test were 46.4%, 75.5%, and 0.61 (95% CI: 0.58–0.64) for low-grade (LG-) BC, and 70.5%, 75.5%, and 0.73 (95% CI: 0.70–0.76) for high-grade (HG-) BC, respectively. Age, UBC® Rapid Test results, smoking status, and hematuria were identified as independent predictors of primary BC. After external validation, nomograms based on these predictors resulted in an area under the curve of 0.79 (95% CI: 0.72–0.87) and 0.95 (95% CI: 0.92–0.98) in predicting LG-BC and HG-BC, respectively, showing excellent calibration associated with a higher net benefit than the UBC® Rapid Test alone for low and medium risk levels in decision curve analysis. An R Shiny app allows the results to be explored interactively and can be accessed at www.blucab-index.net.

Conclusion

The UBC® Rapid Test alone has limited clinical utility for predicting the presence of BC. However, its combined use with BC risk factors including age, smoking status, and hematuria provides a fast, highly accurate, and non-invasive tool for screening patients for primary LG-BC and especially primary HG-BC.