TABLE 3.
PERFORMANCE OUTCOMES OF EARLY SECRETED ANTIGENIC TARGET 6 AND CULTURE FILTRATE PROTEIN 10 IFN-γ RELEASE ASSAY ELISPOT RESPONSES USING CEREBROSPINAL FLUID MONONUCLEAR CELLS AT DIFFERENT CUT POINTS IN THE DEFINITE TUBERCULOUS MENINGITIS AND NONTUBERCULOUS MENINGITIS GROUPS
| A. Definite-TBM (n = 38) compared with unselected non-TBM (n = 48) (AUC, 0.85) | |||||
|---|---|---|---|---|---|
| Cut point* | Sensitivity (95% CI) | Specificity (95% CI) | PPV (95% CI) | NPV (95% CI) | Accuracy (95% CI) |
| ≥20 SFC† | 84% (69–94) | 73% (58–85) | 71% (56–84) | 85% (71–94) | 78% (68–86) |
| ≥46 SFC† | 82% (66–92) | 83% (70–93) | 80% (64–91) | 85% (72–94) | 83% (73–90) |
| ≥228 SFC§ | 58% (41–74) | 94% (83–99) | 88% (69–97) | 74% (61–84) | 78% (68–86) |
| B. Definite-TBM (n = 38) compared with non-TBM (n = 33) that were gram positive CLAT positive (i.e. alternative rapid tests that were concurrently positive) (AUC, 0.83) | |||||
| Cut point |
Sensitivity (CI) |
Specificity (CI) |
PPV (CI) |
NPV (CI) |
Accuracy (CI) |
| ≥20 SFC† | 84% (69–94) | 70% (51–84) | 76% (61–88) | 79% (60–92) | 77% (66–87) |
| ≥59 SFC‡ | 79% (63–90) | 79% (61–91) | 81% (65–92) | 76% (59–89) | 79% (66–88) |
| ≥800 SFC§ | 34% (20–51) | 97% (84–100) | 93% (66–100) | 56% (42–69) | 63% (51–74) |
| C. Definite-TBM (n = 38) compared with non-TBM (n = 15) patients who were gram positive or CLAT negative (i.e., all causes of meningitis other than cryptococcal and acute bacterial meningitides) (AUC, 0.90) | |||||
| Cut point |
Sensitivity |
Specificity |
PPV |
NPV |
Accuracy |
| ≥20 SFC† | 84% (69–94) | 80% (52–96) | 91% (77–98) | 67% (41–87) | 83% (70–92) |
| ≥46 SFC‡,§ | 82% (66–92) | 100% (78–100) | 100% (89–100) | 68% (45–86) | 87% (75–95) |
Definition of abbreviations: AUC = area under the curve; CI = confidence interval; CLAT = cryptococcal antigen latex agglutination test; NPV = negative predictive value; PPV = positive predictive value; SFC = spot-forming cells; TBM = tuberculous meningitis.
Cut point defined as SFCs per million cells.
The manufacturer-recommended cut point for cerebrospinal fluid is ≥ 20 SFC per million mononuclear cells in the early secreted antigenic target 6– or culture filtrate protein 10–containing wells.
Area under the curve–derived cut point by the Youden index, which allows for the selection of an optimal best fit specificity and sensitivity cut point from the receiver operating characteristic curve.
Area under the curve–derived cut-point defining utility as a rule-in test (i.e. high specificity at the expense of suboptimal sensitivity). In Table 3C) the Youdens index and area under the curve are identical).