This section describes efficacy outcomes from the published literature that the committee considered as part of the evidence about this procedure. The efficacy outcomes described below include death occurring more than 30 days after the procedure. Deaths occurring within 30 days or as a result of intracranial haemorrhage are reported as safety outcomes. For more detailed information on the evidence, see the interventional procedure overview.
A systematic review of 8 randomised controlled trials (RCTs), including 2,423 patients, reported that endovascular thrombectomy was associated with improved functional outcomes at 90 day follow‑up (modified Rankin scale score 0 to 2, odds ratio 1.56, 95% confidence interval [CI] 1.32 to 1.85, p<0.00001).
An RCT, included in the systematic review, of 500 patients with acute ischaemic stroke treated by intra‑arterial treatment (intra‑arterial thrombolysis, mechanical clot retrieval, or both) and usual care, or usual care alone reported that the median modified Rankin scale score (7‑point scale ranging from 0 [no symptoms] to 6 [death]) was significantly lower in the intervention group compared with the control group at 90 days (3 compared with 4, adjusted odds ratio 1.67, 95% CI 1.21 to 2.30). In the same study, 33% (76 of 233) of patients in the intervention group had a modified Rankin score of 0 to 2, indicating functional independence, compared with 19% (51 of 267) of patients in the control group (adjusted odds ratio 2.16, 95% CI 1.39 to 3.38).
An RCT, included in the systematic review, of 70 patients treated by mechanical clot retrieval with a retrievable stent or by thrombolysis alone reported that 80% (28 of 35) of patients treated by clot retrieval had an improvement of 8 points or more, or a score of 0 or 1 at day 3, on the National Institutes of Health Stroke Scale (NIHSS; scores range from 0 [normal] to 42 [death]) compared with 37% (13 of 35) of patients in the control group (adjusted odds ratio 6.0, 95% CI 2.0 to 18.0, p=0.002).
Two RCTs, included in the systematic review, of 315 and 206 patients treated by mechanical clot retrieval and standard care, or by standard care alone, reported that 53% (87 of 164) and 44% (absolute numbers not reported) of patients in the intervention group had a modified Rankin score of 0 to 2, respectively, compared with 29% (43 of 147) and 28%, respectively (absolute numbers not reported) of patients in the control group (rate ratio 1.7, 95% CI 1.3 to 2.2; odds ratio 2.1, 95% CI 1.1 to 4.0).
An RCT, included in the systematic review, of 196 patients treated by mechanical clot retrieval with a stent retriever and intravenous tissue plasminogen activator (tPA), or by intravenous tPA alone, reported that 60% (59 of 98) of patients in the intervention group had a modified Rankin score of 0 to 2 at 90 days, compared with 35% (33 of 93) of patients in the control group (risk ratio 1.70, 95% CI 1.23 to 2.33, p<0.001).
The RCT of 500 patients with acute ischaemic stroke treated by intra‑arterial treatment (intra‑arterial thrombolysis, mechanical clot retrieval, or both) and usual care, or by usual care alone, reported that 75% (141 of 187) and 33% (68 of 207) of patients, respectively, had no intracranial artery occlusion on follow‑up CT angiography (odds ratio 6.88, 95% CI 4.34 to 10.94).
The RCT of 196 patients reported at least 90% reperfusion at 27 hours in 83% (53 of 64) of patients treated by mechanical clot retrieval with intravenous tPA compared against 40% (21 of 52) of patients treated by intravenous tPA alone (risk ratio 2.05, 95% CI 1.45 to 2.91, p<0.001). The RCT of 70 patients reported a median reperfusion of 100% at 24 hours for patients treated by mechanical clot retrieval with a retrievable stent compared against 37% for patients treated by thrombolysis alone (odds ratio 4.7, 95% CI 2.5 to 9.0, p<0.001).
The RCT of 206 patients treated by mechanical clot retrieval with a stent retriever and medical therapy, or by medical therapy alone, reported median infarct volumes at 24 hours of 16.3 ml and 38.6 ml, respectively (p=0.02). An RCT of 113 patients treated by mechanical clot retrieval with either a stent retriever or a coil retriever reported successful recanalisation without symptomatic intracranial haemorrhage in 61% (34 of 56) and 24% (13 of 54) of patients, respectively (p=0.0001).
The systematic review of 8 RCTs (2,423 patients) reported no significant difference in mortality at 90 days between the treatment groups (odds ratio 0.84, 95% CI 0.67 to 1.05, p=0.12).The RCTs of 196 and 206 patients reported death within 90 days for 9% (9 of 98) and 18% (19 of 103) of patients treated by mechanical clot retrieval and medical therapy, respectively, compared against 12% (12 of 97) and 16% (16 of 103) of patients, respectively, treated by medical therapy alone (risk ratio 0.74, 95% CI 0.33 to 1.68, p=0.50 and risk ratio 1.2, 95% CI 0.6 to 2.2).
The specialist advisers listed the following key efficacy outcomes: reduction in mortality, revascularisation as assessed by a validated scale, 90‑day functional independence assessed by validated scales including the modified Rankin scale, quality of life, and timeline metrics of procedure.