A comparison of seven prediction scales for symptomatic large anterior vessel occlusion (sLAVO) found that all had good accuracy, high specificity and low sensitivity, although two scored highest.

“The passing of time between stroke onset and starting endovascular thrombectomy (EVT) is the most important factor limiting clinical efficacy,” Dr. Nyika Kruyt of Leiden University Medical Center told Reuters Health by email. “Taking into account that after a work-up in a primary stroke center, transferring a patient to a comprehensive stroke center takes about 60 minutes, it is of paramount importance to triage these patients in the ambulance to allocate them to a comprehensive stroke center immediately.”

As reported in JAMA Neurology, the study was conducted from July 2018-October 2019 in an urban center in the Netherlands with a population of approximately two million people, and included two emergency medical services (EMSs), three comprehensive stroke centers (CSAs) and four primary stroke centers (PSCs).

The analysis included 2,007 patients (mean age, 71; 51 percent, men; median NIHSS score, 4) who received acute stroke codes with clinical observations filled in by EMS paramedics; 7.9 percent had sLAVO. Dr. Kruyt and colleagues used the data to assess the accuracy and feasibility of seven prediction scales: Los Angeles Motor Scale (LAMS); Rapid Arterial Occlusion Evaluation (RACE); Cincinnati Stroke Triage Assessment Tool; Prehospital Acute Stroke Severity (PASS); gaze-face-arm-speech-time; Field Assessment Stroke Triage for Emergency Destination; and gaze, facial asymmetry, level of consciousness, extinction/inattention.

Median symptom-onset-to door time was shorter in patients with sLAVO vs without sLAVO (115 vs. 142 minutes). More patients with than without sLAVO received intravenous thrombolysis (IVT; 38.6 percent vs. 13.7 percent).

Endovascular thrombectomy was done in 100 patients with sLAVO (63.3 percent), with a median door-to-groin-puncture time of 72 minutes. The median door-to-groin-puncture time was shorter for patients who presented directly to a CSC (61 minutes) than for those who first presented in a PSC (114 minutes).

Scale accuracy ranged from 0.79 to 0.89, with LAMS and RACE scales yielding the highest scores.

Specificity was high for all scales (range, 80 percent-93 percent), but sensitivity was low (38 percent-62 percent). Scale feasibility rates ranged from 78 percent to 88 percent, with the highest rate for the PASS scale.

The authors note, “Applying LAMS to our cohort, an urban region with relatively short distances between PSCs and CSCs and a low prevalence of sLAVO, indicated that 13 patients with sLAVO who first presented to a PSC would have benefited from direct allocation to a CSC, 17 patients with ischemic stroke treated with IVT allocated to a PSC would have unnecessarily bypassed a PSC, and 38 patients without sLAVO (including stroke mimics) allocated to a PSC would have been allocated to a CSC.”