Table 2.
Effect sizes for EEG guidance intervention in primary analyses and sensitivity analyses. ∗Effect sizes for mortality and falls are absolute risk differences (marginal effects from logistic regression models). Effect sizes for PCS-12 and MCS-12 are differences in medians from quantile regression. See Supplementary Table S1 for 95% confidence interval (CI). †Models were adjusted for age, sex, ASA physical status, number of comorbid conditions, history of falls, cardiac surgery, abnormal preoperative Short Blessed Test (score >4), preoperative functional capacity <4 metabolic equivalents, length of anaesthesia, and units of packed red blood cells transfused intraoperatively. ‡Post-hoc analyses. In each of these sensitivity analyses, patients in the EEG guidance group in the top quartile of duration of EEG suppression, duration of BIS <40, or median end-tidal anaesthetic concentration within their randomisation stratum (stratified by preoperative history of falls and cardiac vs noncardiac surgery) were excluded. ¶All models for postoperative PCS-12 were adjusted for the preoperative PCS-12 value. All models for postoperative MCS-12 were adjusted for the preoperative MCS-12 value. IQR, inter-quartile range; PCS-12, Veterans RAND 12-Item Health Survey physical composite summary; MCS-12, Veterans RAND 12-Item Health Survey mental composite summary; BIS, bispectral index; MAC, minimum alveolar concentration.
| Analysis | n | Incidence (%) or median [IQR] |
Effect size (99.5% CI)∗ | P value | |
|---|---|---|---|---|---|
| Usual care | EEG guidance | ||||
| Mortality | |||||
| Primary – unadjusted | 1192 | 62/601 (10.3%) | 57/591 (9.6%) | –0.7% (–5.6% to 4.2%) | 0.70 |
| Primary – adjusted† | 1192 | 62/601 (10.3%) | 57/591 (9.6%) | –0.7% (–5.8% to 4.3%) | 0.68 |
| Sensitivity – most EEG Suppression‡ | 1040 | 62/600 (10.3%) | 32/438 (7.3%) | –3.1% (–8.4% to 2.2%) | 0.10 |
| Sensitivity – most BIS <40‡ | 1046 | 62/600 (10.3%) | 44/444 (9.9%) | –0.4% (–5.7% to 4.9%) | 0.82 |
| Sensitivity – highest MAC‡ | 1055 | 62/600 (10.3%) | 48/453 (10.6%) | 0.3% (–5.1% to 5.6%) | 0.89 |
| Falls | |||||
| Primary – unadjusted | 953 | 135/482 (28.0%) | 136/471 (28.9%) | 0.9% (–7.3% to 9.1%) | 0.77 |
| Primary – adjusted | 953 | 135/482 (28.0%) | 136/471 (28.9%) | 1.1% (–7.2% to 9.4%) | 0.71 |
| Sensitivity – most EEG suppression | 843 | 135/481 (28.1%) | 99/362 (27.3%) | –0.7% (–9.5% to 8.0%) | 0.82 |
| Sensitivity – most BIS <40 | 832 | 135/481 (28.1%) | 103/351 (29.3%) | 1.3% (–7.6% to 10.2%) | 0.69 |
| Sensitivity – highest MAC | 838 | 135/481 (28.1%) | 101/357 (28.3%) | 0.2% (–8.6% to 9.0%) | 0.94 |
| PCS-12¶ | |||||
| Primary – unadjusted | 902 | 43.0 [30.6–51.9] | 43.7 [32.8–52.2] | 0.8 (–1.7 to 3.4) | 0.36 |
| Primary – adjusted | 902 | 43.0 [30.6–51.9] | 43.7 [32.8–52.2] | –0.1 (–2.5 to 2.4) | 0.93 |
| Sensitivity – most EEG suppression | 798 | 42.9 [30.6–51.8] | 45.3 [33.4–53.0] | 1.3 (–1.2 to 3.8) | 0.13 |
| Sensitivity – most BIS <40 | 790 | 42.9 [30.6–51.8] | 44.2 [32.9–51.3] | 0.8 (–2.0 to 3.6) | 0.43 |
| Sensitivity – highest MAC | 790 | 42.9 [30.6–51.8] | 43.4 [33.2–51.6] | 0.5 (–2.1 to 3.1) | 0.59 |
| MCS-12¶ | |||||
| Primary – unadjusted | 902 | 58.4 [50.7–61.9] | 58.0 [51.2–62.0] | 0.2 (–1.2 to 1.5) | 0.74 |
| Primary – adjusted | 902 | 58.4 [50.7–61.9] | 58.0 [51.2–62.0] | 0.1 (–1.4 to 1.6) | 0.86 |
| Sensitivity – most EEG suppression | 798 | 58.5 [50.7–61.9] | 57.9 [51.5–61.9] | 0.04 (–1.4 to 1.4) | 0.94 |
| Sensitivity – most BIS <40 | 790 | 58.5 [50.7–61.9] | 58.0 [51.5–62.2] | 0.3 (–1.3 to 1.8) | 0.64 |
| Sensitivity – highest MAC | 790 | 58.5 [50.7–61.9] | 58.2 [51.4–62.2] | 0.3 (–1.2 to 1.7) | 0.59 |