Guidance
4 Efficacy
4 Efficacy
This section describes efficacy outcomes from the published literature that the committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the interventional procedure overview.
4.1 A systematic review of 2,591 patients (2 randomised controlled trials [RCTs] with follow-up intervals of 56 and 25 months, and 19 non-randomised studies with follow-up not stated) reported no difference in stroke rates (any type) between patients having extracranial to intracranial (EC‑IC) bypass (plus best medical treatment) and those having medical treatment only (in the RCTs n=1,691; odds ratio [OR] 0.99, 95% confidence interval [CI] 0.79 to 1.23, p=0.91 and in the non-randomised studies [18 studies], n=881; OR 0.80, 95% CI 0.54 to1.18, p=0.25). In the same systematic review, ischaemic stroke rate was not statistically significantly different between patients having EC‑IC bypass and those having medical treatment only (in the RCTs n=1,573; OR 0.69, 95% CI 0.44 to 1.08, p=0.11 and in the non-randomised studies [13 studies], n=640; OR 0.72, 95% CI 0.44 to 1.18, p=0.19). Two RCTs reported a statistically significantly smaller probability of stroke, vascular event or vascular death among the patients having EC‑IC bypass when compared with patients having medical treatment only (n=1,573; OR 0.68, 95% CI 0.51 to 0.91, p=0.009). No statistically significant difference in ischaemic stroke rate was seen in the systematic review of 2,591 patients (13 non-randomised studies; n=673; OR 0.69, 95% CI 0.45 to 1.04, p=0.079). Two non-randomised studies (n=361) reported no statistically significant difference in intracranial haemorrhage rates between patients having EC‑IC bypass when compared with patients having medical treatment only (OR 1.14, 95% CI 0.44 to 2.93, p=0.79) in the same systematic review. A systematic review of 506 patients reported a statistically significantly lower rate of stroke 12 months after surgery in patients with severe stage I failure (loss of autoregulatory vasodilation) who had EC‑IC bypass (1%) than in patients having medical treatment only (19%, 95% CI 1.17 to 4.08, p=0.015). In the same systematic review, stroke rate was not statistically significantly different in patients with stage II failure (autoregulatory failure characterised by decreases of cerebral blood flow and increases of oxygen extraction fraction) who had EC‑IC bypass (0%) when compared with patients having medical treatment only (13%, 95% CI 0.89 to 3.63, p=0.10). In an RCT of 1,377 patients, EC‑IC bypass surgery was associated with a 14% (90% CI 3 to 34) increased relative risk of fatal and non-fatal stroke (Mantel-Haenszel chi-squared =1.72) at a mean follow-up of 56 months (p value not reported). In an RCT (n=195) comparing 97 patients having EC‑IC bypass with 98 patients who had medical treatment only, ipsilateral ischaemic stroke rate was not statistically significantly different between groups (rate difference 2%, 95% CI −10 to 14, p=0.81) at 2‑year follow-up. A case series of 204 patients who had EC‑IC bypass reported the rate of patients free of stroke or fatal stroke to be 92% (138/150) at 1‑year follow-up and 87% (86/99) at 5‑year follow-up.
4.2 In the systematic review of 2,591 patients, 11 non-randomised studies reported a statistically significantly smaller risk of transient ischaemic attack or amaurosis in patients who had EC‑IC bypass when compared with patients who had medical treatment only (n=524; OR, 0.34, 95% CI 0.16 to 0.69, p=0.003). Three non-randomised studies from the same systematic review reported no statistically significant difference in normalisation of cerebral haemodynamics between patients who had EC-IC bypass and those having medical treatment only (n=56; OR 6.63, 95% CI 1.85 to 23.78).
4.3 The RCT of 1,377 patients reported a graft patency rate, assessed by angiography, of 96% (576/600) in patients who had EC‑IC bypass, at a median of 32 days post-procedure. In the RCT of 195 patients, graft failure rate at 2‑year follow-up was 2% (2/97) in patients who had EC‑IC bypass.
4.4 In an RCT of 43 patients there was no statistically significant difference in neurocognitive function (measured by 14 standardised neuropsychological tests and the Centre for Epidemiological Studies depression scale), at 2‑year follow-up, between patients who had EC‑IC bypass and patients who had medical treatment only (point estimate 0.02, 95% CI, 20.50 to 0.54, p=0.93).
4.5 The specialist advisers listed reduction in stroke rate compared with medical treatment only as the key efficacy outcome.