Evaluation of Fingerstick Cryptococcal Antigen Lateral Flow Assay in HIV-Infected Persons: A Diagnostic Accuracy Study

Cryptococcus neoformans is the most common cause of adult meningitis in sub-Saharan Africa. The cryptococcal antigen (CRAG) lateral flow assay (LFA) has simplified diagnosis as a point-of-care test approved for serum or cerebrospinal fluid (CSF). We evaluated the accuracy of the CRAG LFA using fingerstick whole blood compared with serum/plasma and CSF for diagnosing meningitis.From August 2013 to August 2014, CRAG LFA (IMMY, Norman, Oklahoma) tests were performed on fingerstick whole blood, plasma/serum, and CSF in 207 HIV-infected adults with suspected meningitis in Kampala, Uganda. Venous blood was also collected and centrifuged to obtain serum and/or plasma. CSF was tested after lumbar puncture.Of 207 participants, 149 (72%) had fingerstick CRAG-positive results. There was 100% agreement between fingerstick whole blood and serum/plasma. Of the 149 fingerstick CRAG-positive participants, 138 (93%) had evidence of cryptococcal meningitis with a positive CSF CRAG. Eleven participants (5%) had isolated cryptococcal antigenemia with a negative CSF CRAG and culture, of whom 8 had CSF abnormalities (n = 3 lymphocytic pleocytosis, n = 5 elevated protein, n = 4 increased opening pressure). No persons with cryptococcal meningitis had negative fingersticks.The 100% agreement between whole blood, serum, and plasma CRAG LFA results demonstrates that fingerstick CRAG is a reliable bedside diagnostic test. Using point-of-care CRAG testing simplifies screening large numbers of patients and enables physicians to prioritize on whom to measure CSF opening pressure using manometers.

Keywords

cryptococcal meningitis, cryptococcus, lateral flow assay, HIV, point-of-care systems

Citation

Williams, D. A., Kiiza, T., Kwizera, R., Kiggundu, R., Velamakanni, S., Meya, D. B., ... & Boulware, D. R. (2015). Evaluation of fingerstick cryptococcal antigen lateral flow assay in HIV-infected persons: a diagnostic accuracy study. Clinical Infectious Diseases, 61(3), 464-467.https://doi.org/10.1093/cid/civ263