Table 2.
Diagnostic Test Characteristics and Costs
| Diagnostic Test | Sensitivity | Specificity | Cost (US$) | Reference |
|---|---|---|---|---|
| Total WBC >5 cells/μL | 71–75 % | 95 % | $3.03 | 6,9 |
| Differential White Cell Count >50% (PMN/Lymph) for Bacterial Meningiits | 85–90 % | 43 % | - | 10,11 |
| CSF : Serum Glucose for Other | 100 % | unknown | $3.06 | 12 |
| CSF : Serum Glucose (Ratio <.5) | 81 % | 84 % | - | 11,12 |
| CSF Protein (>50mg/dL) | 88 % | 60 % | $2.63 | 11,12 |
| Bacterial Culture (CSF) | 92 % | 95–99% | $5.52 | 9 |
| Gram’s Stain | 92 % | 99 % | $4.30 | 13 |
| AFB stain <6mL volume for TBM 1 | 0–15 % | 100 % | $4.30 | 6,14–16 |
| AFB >6mL volume for TBM | 52–87 % | 100 % | $4.30 | 16–19 |
| Xpert MTB/RIF Assay for TBM | ~60 % (95% CI: 40–80%) | ~100% in CSF | $15.00 2 | 20–22 |
| India Ink for Cryptococcal Meningitis | 60–84 % | 99 % | $4.30 | 3,6,23–26 |
| Cryptococcal Antigen, latex agglutination | 93–99 % | 93–99 % | $4.83 3 | 27 |
| Cryptococcal Antigen, Lateral Flow Assay (LFA) | 99 % | 99 % | $2.50 | 28,29 |
1
AFB Ziehl-Neelsen stain for TB meningitis (TBM) estimate used in model 30% (95% CI: 10–50%) sensitivity.
2
GeneXpert cartridge cost is $9.98 with the $15 assay cost including shipping and estimated labor.
3
Cryptococcal Antigen, latex agglutination cost is ~$16 in Blantyre, Malawi and Kampala, Uganda.