Influence of renal excretory function on the performance of urine based markers to detect bladder cancer

In hematuria cases urine based tests are used to detect bladder cancer, although the diagnostic yield remains insufficient due to influencing variables, including urinary tract infection. Many patients are elderly with renal insufficiency and have proteinuria as an additional influencing factor. To our knowledge no data are available on the accuracy of urine based bladder cancer tests in conjunction with renal function.

Urine samples of 449 patients with hematuria and histology were included in analysis. Cytology, fluorescence in situ hybridization, immunocytology and nuclear matrix protein 22 assay were done. Renal function was classified as normal, impaired or severely impaired based on serum creatinine, the glomerular filtration rate and proteinuria. False-positive rates were statistically compared in regard to renal function.

A total of 382 patients did not have bladder cancer. There was an increased false-positive rate for creatinine and the glomerular filtration rate. The nuclear matrix protein 22 test showed a 22.0% and 46.7% false-positive rate in the normal and limited function cohorts, respectively (p = 0.05). Similar trends were noted for proteinuria. Indeterminate significance was detected, separating those with severely impaired function for immunocytology and those in the normal group for fluorescence in situ hybridization (p = 0.08 and 0.06, respectively). Proteinuria was a significant factor for urine cytology with increased false-positive results in the absence of urinary tract infection (p = 0.0017 and 0.05, respectively).

To our knowledge this is the first study of renal function and the accuracy of urine based bladder cancer markers. Renal function influences the diagnostic yield. A decreased glomerular filtration rate was associated with increased false-positive nuclear matrix protein 22 results while proteinuria decreased urine cytology specificity. Renal function should be considered when urine based bladder cancer tests are interpreted.