Table 3. Random effects meta-regression analyses of Early and Delayed surgery time for overall mortality.

Characteristic	N. studies	N. participants	OR (95% CI)	p-value
Continuous variables
Age (per 10 years)	28	159772	0.97 (0.36 to 2.63)	0.96
Female prevalence (per 10% more)	32	187885	1.03 (0.92 to 1.16)	0.55
Study year (per 10 years)	34	191873	0.90 (0.7 to 1.18)	0.46
Continuous time (per 24 hours)	34	191873	0.22 (0.00077 to 63.62)	0.59
Categorical variables
Study design
Prospective (reference)	15	35112	1
Retrospective	20	156761	1.17 (0.82 to 1.66)	0.36
Data source category
Clinical data (reference)	24	46843	1
Administrative data	10	144053	1.05 (0.72 to 1.53)	0.78
Study quality
8–9 stars (reference)	18	149228	1
1–7 stars	17	42645	1.05 (0.73 to 1.5)	0.79
Study location
Non-US study (reference)	23	129179	1
US study	12	62694	0.94 (0.65 to 1.35)	0.74
Early surgery time cut-off definition
<12 hours	2	1500	1.2 (0.55 to 2.65)	0.62
<24 hours (reference)	16	97100	1
<48 hours	14	85378	0.97 (0.65 to 1.43)	0.87
<96–120 hours	3	7895	0.90 (0.46 to 1.78)	0.77
Baseline risk
Risk<21%	17	85826	1
Risk>21%	18	106047	0.86 (0.61 to 1.22)	0.40