Table 3.
Performance of GFAP and PreSS for identification of stroke, ICrH, and LVO
| Stroke subtype | Sensitivity% (95% CI) | Specificity% (95% CI) | PPV% (95% CI) | NPV% (95% CI) | LR+ (95% CI) | LR− (95% CI) |
|---|---|---|---|---|---|---|
| GFAP (n = 299) | ||||||
| ICrH | 25.0 (11.5–43.4)a | 100.0 (98.6–100.0)a | 100.0 (63.1–100.0)a | 91.8 (88.0–94.6)a | – | 0.75 (0.61–0.92)a |
| PreSS part 1 (n = 299) Stroke/TIA suspected if PreSS part 1 ≥ 1 | ||||||
| Stroke/TIA | 94.4 (89.9–97.3) | 17.4 (11.1–25.3) | 62.7 (56.6–68.5) | 67.7 (48.6–83.3) | 1.14 (1.04–1.25) | 0.32 (0.16–0.66) |
| PreSS part 2 (n = 268) LVO suspected if PreSS part 1 ≥ 1 and PreSS part 2 ≥ 2 | ||||||
| LVO | 55.6 (35.3–74.5) | 77.2 (71.4–82.3) | 21.4 (12.5–32.9) | 93.9 (89.7–96.8) | 2.43 (1.62–3.67) | 0.58 (0.38–0.88) |
| PreSS and GFAP combined (as used in the decision tree) | ||||||
| Step 1 Stroke and TIA (Group 4) | 94.4 (89.9–97.3) | 17.4 (11.1–25.3) | 62.7 (56.6–68.5) | 67.7 (48.6–83.3) | 1.14 (1.04–1.25) | 0.32 (0.16–0.66) |
| Step 2 ICrH (Group 1) | 25.0 (11.5–43.4)a | 100.0 (98.6–100.0)a | 100.0 (63.1–100.0)a | 91.8 (88.0–94.6)a | – | 0.75 (0.61–0.92)a |
| Step 3 LVO (Group 2) | 55.6 (35.3–74.5)a | 82.4 (77.3–86.7)a | 23.8 (14.0–36.2)a | 94.9 (91.3–97.3)a | 3.15 (2.06–4.81)a | 0.54 (0.35–0.83)a |
GFAP glial fibrillary acidic protein, ICrH intracranial hemorrhage, LR+ positive likelihood ratio, LR− negative likelihood ratio, LVO large-vessel occlusion, NIHSS National Institutes of Health Stroke Scale, NPV negative predictive value, PPV positive predictive value, PreSS Prehospital Stroke Score, TIA transient ischemic attack
aGFAP cutoff set at 5369 pg/mL