Assessment of Diagnostic Yield of Nonculture Infection Testing on Cerebrospinal Fluid in Immune-Competent Children

IMPORTANCE: Nonculture infection tests of cerebrospinal fluid (CSF) samples using polymerase chain reaction and antigen or antibody assays are frequently ordered on lumbar puncture specimens concurrently with routine CSF cell counts, but the value of CSF infection testing in otherwise healthy children is unknown. OBJECTIVE: To determine the value of nonculture CSF infection testing in immune-competent children with normal CSF cell counts. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study reviewed screening and diagnostic tests in the electronic medical record system of a large academic tertiary care children’s hospital. Records of children aged 0.5 to 18.9 years (n = 4083) who underwent lumbar puncture (n = 4811 procedures) in an inpatient or outpatient facility of Children's Hospital of Philadelphia between July 1, 2007, and December 31, 2016, were reviewed. Those with indwelling CSF shunts or catheters; those with active or past oncologic, immunologic, or rheumatologic conditions; or those taking immune-suppressing medications were excluded from analysis. This study was conducted from July 20, 2017, to March 13, 2019. MAIN OUTCOMES AND MEASURES: Outcome variables included frequency of nonculture CSF infection testing and frequency of positive results in the entire cohort, and among those with normal cell counts. Normal cell counts were defined as CSF white blood cell counts lower than 5 cells/μL and CSF red blood cell counts lower than 500 cells/μL. RESULTS: In total, 4811 lumbar puncture procedures were performed on 4083 unique children, with a median (range) age of 7.4 (0.5-18.9) years, 2537 boys (52.7%), and 3331 (69.2%) with normal CSF cell counts. At least 1 nonculture CSF infection test was performed on 1270 lumbar puncture specimens with normal cell counts (38.1%; 95% CI, 36%-40%), and more tests were performed in the summer months. Only 18 (1.4%; 95% CI, 0.9%-2.2%) of 1270 lumbar puncture specimens with normal cell counts had at least 1 nonculture infection test with a positive result; 2 of these 18 children required clinical intervention for their positive results, but each also had other clear clinical signs of infection. CONCLUSIONS AND RELEVANCE: Nonculture CSF infection testing appeared to be common in immune-competent children with normal CSF cell counts, but positive results were uncommon and were not independently associated with clinical care; delaying the decision to send nonculture infection tests until CSF cell counts are available could reduce unnecessary diagnostic testing and medical costs, which may improve value-based care.