Diagnostic Accuracy of the Biosynex CryptoPS Cryptococcal Antigen Semiquantitative Lateral Flow Assay in Patients with Advanced HIV Disease.
J Clin Microbiol
; 59(1)2020 12 17.
Article
em En
| MEDLINE
| ID: mdl-33087436
ABSTRACT
High cryptococcal antigen (CrAg) titers in blood are associated with subclinical meningitis and mortality in CrAg-positive individuals with advanced HIV disease (AHD). We evaluated a novel semiquantitative lateral flow assay (LFA), CryptoPS, that may be able to identify individuals with high CrAg titers in a cohort of AHD patients undergoing CrAg screening. In a prospective cohort of patients with AHD (CD4 cell count, ≤200/µl) receiving CD4 count testing, whole blood was tested for CrAg by CryptoPS and the IMMY LFA; the two assays were conducted by two different operators, each blind to the results of the other assay. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CryptoPS were assessed against the IMMY LFA as a reference. CryptoPS low-titer (T1 band) and high-titer (T2 band) results were compared with IMMY LFA titers obtained through serial dilution. A total of 916 specimens were tested. The sensitivity of the CryptoPS assay was 61.0% (25/41) (95% confidence interval [95% CI], 44.5 to 75.8%), its specificity was 96.6% (845/875) (95% CI, 95.1 to 97.7%), its PPV was 45.5% (95% CI, 32.0 to 59.4%), and its NPV was 98.1% (95% CI, 97.0 to 98.9%). All (16/16) CryptoPS false-negative results were obtained for samples with IMMY titers of ≤1160. Of 29 patients (30 specimens) who tested positive by CryptoPS but negative by the IMMY LFA, none developed cryptococcal meningitis over 3 months of follow-up without fluconazole. Median CrAg titers were 120 (interquartile range [IQR], 0 to 1160) in CryptoPS T1-positive samples and 12,560 (IQR, 11,280 to 110,240) in T2-positive samples. We conclude that the diagnostic accuracy of the CryptoPS assay was suboptimal in the context of CrAg screening, with poor sensitivity at low CrAg titers. However, the CryptoPS assay reliably detected individuals with high titers, which are associated with poor outcomes.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Infecções por HIV
/
Meningite Criptocócica
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Cryptococcus
Tipo de estudo:
Diagnostic_studies
/
Observational_studies
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Prognostic_studies
/
Risk_factors_studies
Limite:
Humans
Idioma:
En
Ano de publicação:
2020
Tipo de documento:
Article