When Is a Positive Test for Pediatric Growth Hormone Deficiency a True-Positive Test?
George M. Bright, Peter A. Morris, Ron G. Rosenfeld
Abstract
BACKGROUND: In most cases, the growth hormone stimulation test is a necessary component for the diagnosis of growth hormone deficiency (GHD) in children. Diagnostic testing can lead to unnecessary treatment of children with false-positive test results and omission of treatment in children with false-negative results. False-positive results are suggested by the absence of typical growth responses in treated children and false-negative results are suggested by continued growth failure in those left untreated. SUMMARY: The probability that a positive test result indicates the presence of the condition (true positive) depends on the prevalence of that condition in the test population and the false positive rate of the test. This probability has been estimated using published data on the prevalence of GHD in children and the false positive rates estimated from performance of stimulation tests in normally growing children and from repeated testing in short children. Because of the low prevalence of GHD and the substantial false positive rate of the test, the probability of a true-positive result in a child with short stature is 0.028, or about 1 in 36 cases. Key Messages: In children with short stature, most positive growth hormone stimulation test results will be false-positive results, resulting in growth hormone treatment of children misdiagnosed as growth hormone deficient. Additional information is required for accurate diagnosis and prediction of successful treatment outcomes in children. Improvements in diagnostic accuracy and treatment outcome predictions can be anticipated from the use of additional predictive enrichment markers identified and evaluated in broadly based studies of growth hormone treatment in children.