Table 3.
Assessment Toolsa for Meningitis in an Anthrax Mass Casualty Incident: Derivation, Validation, and Sensitivity Analyses
| Assessment Tools | TP b | FN | FP | TN | Sensitivity (95% CI), % | Specificity (95% CI), % | LR+ (95% CI) | LR− (95% CI) |
|---|---|---|---|---|---|---|---|---|
| Derivation Sample c | ||||||||
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| 1. Headache without: AMS, MS, ONSAMS, MS, ONS d | 6 | 11 | 24 | 109 | 35 (13–58) | 82 (75–88) | 2.0 (0.9–4.1) | 0.79 (0.55 – 1.13) |
| 2. One of the following: AMS, MS, ONS | 70 | 17 | 19 | 133 | 80 (72–89) | 88 (82–93) | 6.4 (4.2–9.9) | 0.22 (0.15 – 0.34) |
| 3. Two of the following: AMS, MS, ONS | 52 | 35 | 0 | 152 | 60 (49–70) | 100 (99–100)e | 182.6 (11.4–2921.1) e | 0.40 (0.31 – 0.52) |
| 4. One of the following: SHA, AMS, MS, ONS | 76 | 11 | 25 | 127 | 87 (80–94) | 84 (78–89) | 5.3 (3.7–7.7) | 0.15 (0.09 – 0.26) |
| 5. Two of the following: SHA, AMS, MS, ONS | 57 | 30 | 1 | 151 | 66 (56–76) | 99 (98–100) | 99.6 (14.0–706.6) | 0.35 (0.26 – 0.46) |
| 6. One of the following: SHA, AMS, MS, ONS, N/V | 77 | 10 | 50 | 102 | 89 (82–95) | 67 (60–75) | 2.7 (2.1–3.4) | 0.17 (0.09 – 0.31) |
| 7. Two of the following: SHA, AMS, MS, ONS, N/V | 65 | 22 | 7 | 145 | 75 (66–84) | 95 (92–99) | 16.2 (7.8–33.8) | 0.27 (0.18 – 0.38) |
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| Validation Samples c | ||||||||
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| 4. One of the following: SHA, AMS, MS, ONS | ||||||||
| Adult Sample (n = 61) | 17 | 2 | 6 | 36 | 89 (76–100) | 86 (75–96) | 6.3 (2.9–13.3) | 0.12 (0.03 – 0.46) |
| Pediatric Subset (n = 55) | 15 | 3 | 4 | 33 | 83 (66–100) | 89 (79–99) | 7.7 (3.0–19.9) | 0.19 (0.07 – 0.53) |
| 5. Two of the following: SHA, AMS, MS, ONS | ||||||||
| Adult Sample (n = 61) | 12 | 7 | 1 | 41 | 63 (41–85) | 98 (93–100) | 26.5 (3.7–189.6) | 0.38 (0.21 – 0.68) |
| Pediatric Subset (n = 55) | 7 | 11 | 0 | 37 | 39 (16–61) | 99 (95–100) e | 30.0 (1.8–497.9) e | 0.61 (0.42 – 0.88) |
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| Sensitivity Analyses c | ||||||||
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| 4. One of the following: SHA, AMS, MS, ONS | ||||||||
| Completeness Score >11 (n = 133) | 54 | 4 | 17 | 58 | 93 (87–100) | 77 (68–87) | 4.1 (2.7–6.3) | 0.09 (0.03 – 0.23) |
| Completeness Score >9 (n = 247) | 90 | 9 | 26 | 122 | 91 (85–97) | 82 (76–89) | 5.2 (3.6–7.4) | 0.11 (0.06 – 0.21) |
| 5. Two of the following: SHA, AMS, MS, ONS | ||||||||
| Completeness Score >11 (n = 133) | 40 | 18 | 0 | 75 | 69 (57–81) | 99 (98–100) e | 104.3 (6.6–1662.0) e | 0.31 (0.21 – 0.46) |
| Completeness Score >9 (n = 247) | 66 | 33 | 0 | 148 | 67 (57–76) | 100 (99–100) e | 198.2 (12.4–3164.7) e | 0.33 (0.25 – 0.44) |
… Suspected meningitis cases are excluded.
TP=true positive, FN=false negative, FP=false positive, TN=true negative, LR+=likelihood ratio positive, LR−=likelihood ratio negative.
Derivation sample based on an 80% random sample of adults (≥18 years) with systemic anthrax, adult validation sample is the remaining 20% of adults, pediatric subset (0–17 years old) is all children, and sensitivity analyses using completeness score are based on the full dataset of 363 case-patients.
AMS=altered mental status, MS=meningeal signs, ONS=other neurological signs, SHA=severe headache, N/V=nausea or vomiting.
Continuity correction factor of 0.5 added to TP, FN, FP, TN.