Table 2

Subgroup analysis of N-acetylcysteine (NAC) trials

Characteristic	Stratum	N/n	OR	95% CI	I²
Diabetic status	Diabetic	1/87	0.75	0.21 to 2.67	n/a
Diabetic status	Non-diabetic	26/5607	0.77	0.65 to 0.91	39
Intervention	CAG	14/3996	0.80	0.65 to 0.99	50
Intervention	CAG/PCI	13/1698	0.72	0.55 to 0.93	16
Contrast dose*	<125 mL	13/4300	0.89	0.74 to 1.08	13
Contrast dose*	>125 mL	13/1344	0.45	0.32 to 0.64	28
Renal function*	sCr ≥1.1	11/1640	0.76	0.57 to 1.02	0
Renal function*	sCr ≥1.4	13/980	0.46	0.32 to 0.65	46
NAC dose*	<2400 mg	6/1214	0.74	0.54 to 1.00	53
	=2400 mg	13/1349	0.69	0.49 to 0.98	32
	>2400 mg	7/3071	0.87	0.68 to 1.11	31
NAC route	Oral	23/4701	0.77	0.64 to 0.94	34
NAC route	Intravenous	4/993	0.75	0.54 to 1.04	60
Date	1999–2008	20/2396	0.62	0.48 to 0.80	41
Date	2009–present	7/3298	0.92	0.73 to 1.13	0
Risk of bias	Low risk	10/3975	0.82	0.67 to 1.00	52
Risk of bias	High risk	17/1719	0.67	0.49 to 0.90	26

*The sum of the trials across strata for contrast dose do not sum 27 because one trial did not report average contrast dose. Likewise for renal function, three trials did not describe baseline sCr adequately and were excluded. Likewise for NAC, dose one trial based dose on patient weight and was excluded.
CAG, coronary angiography; N, number of trials; PCI, percutaneous coronary intervention; n, total number of participants; sCr, serum creatinine.