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Evaluation of fingerstick cryptococcal antigen lateral flow assay in HIV-infected persons: a diagnostic accuracy study.

ABSTRACT: 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.

SUBMITTER: Williams DA

PROVIDER: S-EPMC4503809 | biostudies-literature | 2015 Aug

REPOSITORIES: biostudies-literature

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Evaluation of fingerstick cryptococcal antigen lateral flow assay in HIV-infected persons: a diagnostic accuracy study.

Williams Darlisha A DA Kiiza Tadeo T Kwizera Richard R Kiggundu Reuben R Velamakanni Sruti S Meya David B DB Rhein Joshua J Boulware David R DR

Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 20150401 3

<h4>Background</h4>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.<h4>Methods</h4>From August 2013 to August 2014, CRAG LFA (IMMY, Norman, Oklahoma) tests were perform ...[more]

PMID: 25838287

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Project description:Higher cryptococcal antigen (CrAg) titers are strongly associated with mortality risk in individuals with HIV-associated cryptococcal disease. Rapid tests to quantify CrAg levels may provide important prognostic information and enable treatment stratification. We performed a laboratory-based validation of the IMMY semiquantitative cryptococcal antigen (CrAgSQ) lateral flow assay (LFA) against the current gold standard CrAg tests. We assessed the diagnostic accuracy of the CrAgSQ in HIV-positive individuals undergoing CrAg screening, determined the relationship between CrAgSQ scores and dilutional CrAg titers, assessed interrater reliability, and determined the clinical correlates of CrAgSQ scores. A total of 872 plasma samples were tested using both the CrAgSQ LFA and the conventional IMMY CrAg LFA, of which 692 were sequential samples from HIV-positive individuals undergoing CrAg screening and an additional 180 were known CrAg-positive plasma samples archived from prior studies. Interrater agreement in CrAgSQ reading was excellent (98.17% agreement, Cohen's kappa 0.962, P < 0.001). Using the IMMY CrAg LFA as a reference standard, CrAgSQ was 93.0% sensitive (95% confidence interval [CI] 80.9% to 98.5%) and 93.8% specific (95% CI, 91.7% to 95.6%). After reclassification of discordant results using CrAg enzyme immunoassay testing, the sensitivity was 98.1% (95% CI, 90.1% to 100%) and specificity 95.8% (95% CI, 93.9% to 97.2%). The median CrAg titers for semiquantitative score categories (1+ to 4+) were 1:10 (interquartile range [IQR], 1:5 to 1:20) in the CrAgSQ 1+ category, 1:40 (IQR, 1:20 to 1:80) in the CrAgSQ 2+ category, 1:640 (IQR, 1:160 to 1:2,560) in the CrAgSQ 3+ category, and 1:5,120 (IQR, 1:2,560 to 1:30,720) in the CrAgSQ 4+ category. Increasing CrAgSQ scores were strongly associated with 10-week mortality. The IMMY CrAgSQ test had high sensitivity and specificity compared to the results for the IMMY CrAg LFA and provided CrAg scores that were associated with both conventional CrAg titers and clinical outcomes.

Dataset Information

Evaluation of fingerstick cryptococcal antigen lateral flow assay in HIV-infected persons: a diagnostic accuracy study.

Publications

Evaluation of fingerstick cryptococcal antigen lateral flow assay in HIV-infected persons: a diagnostic accuracy study.

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