Table 1.

Summary of studies on BIS-guided anesthesia and intraoperative awareness focusing on cardiac surgical patients

Characteristics	Myles et al.; 2004 [23]	Avidan et al.; 2008 [21]	Avidan et al., 2011 [18]
Number of patients studied	2,463	1,941	5,713
Study period	2000-2002	2005-2006	2008-2010
Study design	Randomized clinical trial	Randomized clinical trial	Randomized clinical trial
Proportion of cardiac surgery patients, %	49	27	36
Proportion of patients receiving TIVA (%)	43	0	0
Type of intervention	BIS-guided anesthesia vs. routine care	BIS-guided vs. ETAC-guided anesthesia	BIS-guided vs. ETAC guided anesthesia
Incidence of definite awareness among cardiac surgical patients including lung transplants (%)	BIS group: 1/607 (0.16%) Routine care: 5/605 (0.8%)	BIS group: 0/270 (0%)	BIS group: 5/1004 0.5%
		ETAC group: 2/255 (0.78%)	ETAC group: 1/1037 (0.1%)
Incidence of definite or possible awareness among cardiac surgical patients including lung transplants (%)	BIS group: 9/607 (1.5%) Routine care: 11/605 (1.8%)	BIS group: 2/270 (0.74%)	BIS group: 11/1004 (1.1%)
		ETAC group: 3/255 (1.18%)	ETAC group: 4/1037 (0.4%)
Absolute risk reduction by BIS-guided anesthesia for definite awareness, % (95% CI)	0.64% (-0.13% to 1.5%)	0.78% (-0.73% to 2.8%)	-0.4% (-1.07% to 0.13%)
Absolute risk reduction by BIS-guided anesthesia for definite or possible awareness, % (95% CI)	0.34% (-1.1% to 1.8%)	0.44% (-1.6% to 2.7%)	-0.71% (-1.6% to 0.06%)
Number needed to treat to prevent one definite awareness event (95% CI) with BIS-guided care*	151 (NNTH 778 to ∞ to NNTB 69)	128 (NNTH 137 to ∞ to NNTB 36)	NNTH 250 (NNTH 93 to ∞ to NNTB 769)
Number needed to treat to prevent one definite or possible awareness event (95% CI) with BIS-guided care*	298 (NNTH 91 to ∞ to NNTB 56)	227 (NNTH 63 to ∞ to NNTB 37)	NNTH 141 (NNTH 63 to ∞ to NNTB 1667)

ASA, American Society of Anesthesiologists, BIS, Bispectral Index; CI, confidence interval; ETAC, end-tidal anesthetic gas concentration; TIVA, total intravenous anesthesia.

^*Confidence intervals span zero and hence reported as number needed to treat to harm (NNTH) and number needed to treat to benefit (NNTB) as recommended by Altman.¹⁰⁵