Table 3.
Comparison of clinical scales for prehospital prediction of LVO
| sNIHSS-8 | sNIHSS-5 | 3I-SS | LAMS | RACE | CPSSS | FAST-ED | PASS | sNIHSS-EMS | |
| Reference | 3 | 3 | 10 | 16 | 11 | 12 | 15 | 14 | 10 |
| Scale characteristics | |||||||||
| No. of items assessed* | 7 | 4 | 3 | 3 | 5† | 3 | 5 | 3 | 7 |
| Score range | 0–24 | 0–16 | 0–6 | 0–5 | 0–9 | 0–4 | 0–9 | 0–3 | 0–29 |
| NIHSS compatible item assessment | ● | ● | – | – | – | – | – | – | ● |
| Stroke recognition | ● | ● | – | – | – | – | – | – | ● |
| Stroke severity grading | ● | ● | – | (●) | (●) | – | – | – | ● |
| LVO prediction | ● | ● | ● | ● | ● | ● | ● | ● | ● |
| LVO prediction, test characteristics, own cohort (n=741, 44% LVO) | |||||||||
| Cut-point used‡ | ≥6 | ≥3 | ≥4 | ≥4 | ≥5 | ≥2 | ≥4 | ≥2 | ≥6 |
| Sensitivity | 64% | 69% | 40% | –§ | 59% | 59% | 60% | 68% | 70% |
| Specificity | 88% | 81% | 95% | –§ | 91% | 89% | 90% | 84% | 81% |
| PPV | 78% | 70% | 85% | –§ | 81% | 77% | 80% | 74% | 70% |
| NPV | 79% | 80% | 71% | –§ | 78% | 77% | 78% | 81% | 81% |
| LVO prediction, test characteristics, original cohorts¶ | |||||||||
| Cohort (N (% LVO)) | – | – | 83 (35%) | 119 (62%) | 357 (21%)** | 303 (73%) | 727 (33%) | 3127 (35%)†† | – |
| Sensitivity | – | – | 67% | 81% | 85% | 83% | 61% | 66% | – |
| Specificity | – | – | 92% | 89% | 68% | 40% | 89% | 83% | – |
| PPV | – | – | 74% | ND | 42% | ND | 72% | 68% | – |
| NPV | – | – | 89% | ND | 94% | ND | 82% | 81% | – |
*Motor arm (or leg) scored for each side (left or right) is counted as one item.
†If right-sided hemiparesis, aphasia is assessed; if left-sided hemiparesis, agnosia.
‡Cut-points according to original publications, with exception of the sNIHSS-8 and sNIHSS-5. Based on the Youden indices calculated from our data, optimal cut-points are different: 3I-SS ≥2, RACE ≥3, CPSSS ≥1, FAST-ED ≥3.
§Grip strength was not routinely documented, therefore external validation of the LAMS was not possible.
¶Definition of LVO according to original publications (3I-SS: carotid T or M1; LAMS: ICA, M1, M2, M3/4, ACA; RACE: terminal ICA, M1, tandem CCA/ICA+M1, BA; CPSSS: ICA, M1, tandem ICA+M2, BA; FAST-ED: ICA, M1, M2, BA; PASS: ‘visible clot in the anterior or posterior circulation on CTA or MRA’; abbreviations within the main text).
**Including cases assessed by transcranial duplex only (n=197).
††Only patients who received intravenous tissue plasminogen activator; two-thirds of entire cohort was taken as a random sample for derivation. In the remaining one-third, sensitivity was 61%, specificity 83%.
ACA, anterior cerebral artery; BA, basilar artery; CCA, common carotid artery; 3I-SS, 3-item Stroke Scale; CPSSS, Cincinnati Prehospital Stroke Severity Scale; FAST-ED, Field Assessment Stroke Triage for Emergency Destination; ICA, internal carotid artery; LAMS, Los Angeles Motor Scale; LVO, large vessel occlusion; ND, no data; NIHSS, NIH Stroke Scale; NPV, negative predictive value; PASS, Prehospital Acute Stroke Severity Scale; PPV, positive predictive value; RACE, Rapid Arterial Occlusion Evaluation scale; sNIHSS-EMS, shortened NIHSS for emergency medical services.