Effect of intravesical instillations on the human complement factor H related protein (BTA stat) test

The BTA stat is a rapid, non-invasive, qualitative urine test that detects bladder tumor-associated antigen (human complement factor H related protein) in urine. The sensitivity of this test is superior to that of urine cytology in detecting primary and recurrent tumors of the urinary bladder. Intravesical instillations are widely used to avoid recurrences and even progression. The objective of this study was to evaluate the effect of intravesical treatments on the BTA stat Test.

501 consecutive patients followed up for bladder cancer were studied, of which 490 were eligible for analysis. Three hundred and twenty-seven (66.7%) of the patients had no history of intravesical treatments, whereas the remaining 163 (33.3%) had received treatments: 66 (40.5%) at the time of evaluation. A voided urine sample was obtained prior to cystoscopy and split for culture and BTA stat testing. The overall sensitivity and specificity were calculated and compared to the patients with no, past and present instillations.

The overall sensitivity for the BTA stat Test was 56.6%, and the specificity was 76.4%. The specificity of the BTA stat Test was 80.7, 70.7 and 65.3% in those with no, past or present intravesical instillation treatments, respectively. The difference in specificity between those with no and present instillations was significant (p = 0.023), whereas the notable difference between those with no and past instillations did not reach significance (p = 0.076), nor was the difference between patients with past and present instillations significant (p = 0.558). Present instillation of mitomycin C had the strongest adverse effect on the test as the specificity was only 25.0%, whereas past treatment did not interfere with testing. The adverse effect of BCG treatment on testing extended.

The overall specificity of the test is decreased in patients receiving intravesical treatments, whereas past treatments did not interfere with testing in general. However, the adverse effect of BCG on testing seems to extend, and therefore it is suggested that the BTA stat Test should not be used in patients having received BCG, and in those with present instillation of any type.