To the Editor: The results of the study of the NMP22 assay for bladder cancer surveillance by Dr Grossman and colleagues1 do not justify adopting this test for such use. First, the assessment of the sensitivity and specificity of the NMP22 assay was flawed. Diagnostic test evaluation requires the uniform application of an unambiguous reference standard.2 The authors used the reference standard of cystoscopy, but it is unclear how often it was applied. The cross-sectional design of the study implies that all patients underwent a single cystoscopy at the time of NMP22 testing. However, at least 9 patients—and as many as 574 not diagnosed as having cancer at their initial cystoscopy—also underwent repeat cystoscopy. If not all 574 patients underwent a repeat examination, then the reference standard was applied inconsistently, raising questions about whether the NMP22 result prompted the repeat cystoscopy, thus inflating the sensitivity of the NMP22 assay (workup bias).
Even if the reference standard were applied uniformly, it is difficult to understand what a recommended strategy for the use of NMP22 would be. Its low sensitivity (49.5%) argues against its use as an alternative to cystoscopy. The strategy of using the NMP22 assay in conjunction with the initial cystoscopy provides no advantage, since adding the NMP22 assay apparently had no role in identifying the 9 additional cancers (4 of which were found because of increased symptoms and 5 because of “close monitoring”). But adding the NMP22 assay does increase false alarms (false-positive rate of 13%). Alternatively, the strategy of using NMP22 as a monitoring tool between cystoscopies, suggested by the authors, was not examined in this study.
The goal of surveillance is to reduce bladder cancer mortality, not simply to find more cancer. The larger question of whether routine surveillance for bladder cancer reduces bladder cancer mortality remains unaddressed.3 - 4
Financial Disclosures: None reported.
Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature
Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
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