The LaBrosse spot test in the diagnosis of neuroblastoma

Abstract

The LaBrosse spot test was done on the urine of 210 children suspected to have neuroblastoma. Of the nine children ultimately proved to have neuroblastoma, eight showed a positive LaBrosse test (89%). The diagnosis was confirmed in 8 out of 22 children with positive tests (36.4%). The proportion of true positives was shown to correspond very closely to the expected incidence calculated on the basis of the Bayes Theorem (36.5%). It is shown that the high percentage of false positives is a consequence of the probability theory (Bayes Theorem) rather than an inherent weakness of the test.