• Terin T Sytsma, Elitza S Theel, Zelalem Temesgan, and Michel Toledano.
• Division of Community Internal Medicine, Mayo Clinic, Rochester, MN, USA.
• J Gen Intern Med. 2021 Jan 1; 36 (1): 77-83.

BackgroundInappropriate use of diagnostic tests contributes to rising healthcare expenditures, and improving appropriate utilization rates is important for high-value patient care. The Venereal Disease Research Laboratory (VDRL) test performed in cerebrospinal fluid (CSF) has historically been improperly utilized, although there is no recent evaluation of its use in clinical practice.ObjectivesQuantify the rates of appropriate CSF-VDRL testing, determine the CSF-VDRL false-positivity rate, and describe the causes of false-positive CSF-VDRL reactivity.DesignRetrospective cohort study PATIENTS: A total of 32,626 patients with CSF-VDRL testing at one of three Mayo Clinic sites (Rochester, MN; Jacksonville, FL; and Scottsdale, AZ) from January 1, 1994, to February 28, 2018.Main MeasuresRate of appropriate CSF-VDRL test utilization from January 1, 2011, to December 31, 2017, and CSF-VDRL true- and false-positivity rates from January 1, 1994, to February 28, 2018.Key ResultsAmong 8553 persons with negative CSF-VDRL results, testing was inappropriately ordered for 8399 (98.2%) of these patients. The word "syphilis" or "neurosyphilis" appeared in the notes of 1184 (13.8%) individuals with a negative CSF-VDRL result. From January 1994 through February 2018, 33,933 CSF-VDRL tests were performed on 32,626 individual patients. Among the 60 positive CSF-VDRL results, 43 (71.7%) were true-positives and 17 (28.3%) were false-positives. All patients with false-positive CSF-VDRL results were tested unnecessarily. Neoplastic meningitis was a common cause of false-positive CSF-VDRL results.ConclusionsInappropriate use of CSF-VDRL testing for the diagnosis of neurosyphilis remains problematic in clinical practice. Following recommended testing algorithms would prevent unnecessary testing and minimize false-positive results.

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