Comparison 1. Early versus standard initiation.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1.1 Death	12		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
1.1.1 Death at day 30	12	4826	Risk Ratio (M‐H, Random, 95% CI)	0.97 [0.87, 1.09]
1.1.2 Death after 30 days	7	4534	Risk Ratio (M‐H, Random, 95% CI)	0.99 [0.92, 1.07]
1.2 Death or non‐recovery kidney function at day 90	6	4011	Risk Ratio (M‐H, Random, 95% CI)	0.91 [0.74, 1.11]
1.3 Recovery of kidney function	10		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
1.3.1 Patients free from KRT according to ITT analysis (all patients)	10	4717	Risk Ratio (M‐H, Random, 95% CI)	1.07 [0.94, 1.22]
1.3.2 Survivors free from KRT according to ITT after 30 days	10	2510	Risk Ratio (M‐H, Random, 95% CI)	1.02 [0.97, 1.07]
1.4 Adverse events	7		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
1.4.1 Any adverse event	5	3983	Risk Ratio (M‐H, Random, 95% CI)	1.23 [0.90, 1.68]
1.4.2 Hypophosphataemia	1	2927	Risk Ratio (M‐H, Random, 95% CI)	1.80 [1.33, 2.44]
1.4.3 Hypotension	5	3864	Risk Ratio (M‐H, Random, 95% CI)	1.54 [1.29, 1.85]
1.4.4 Cardiac‐rhythm disorder	6	4483	Risk Ratio (M‐H, Random, 95% CI)	1.35 [1.04, 1.75]
1.4.5 Infection	5	4252	Risk Ratio (M‐H, Random, 95% CI)	1.33 [1.00, 1.77]
1.4.6 Bleeding	6	4358	Risk Ratio (M‐H, Random, 95% CI)	0.91 [0.71, 1.18]
1.4.7 Thrombocytopenia	1	106	Risk Ratio (M‐H, Random, 95% CI)	1.03 [0.20, 5.35]
1.5 Length of stay	7		Mean Difference (IV, Random, 95% CI)	Subtotals only
1.5.1 Length of stay in ICU	5	4240	Mean Difference (IV, Random, 95% CI)	‐1.01 [‐1.60, ‐0.42]
1.5.2 Length of stay in hospital	7	4589	Mean Difference (IV, Random, 95% CI)	‐2.45 [‐4.75, ‐0.14]