Table 4. Subgroup analysis to investigate the strategies of ACEi/ARB usage and incidence of AKI in patients grouped by different causes of ICU admission and risk factors of AKI.

Subgroup (event/subjects, %)	ACEi/ARB users vs. non-users
	Crude HR	95% CI	p effect	p interaction
Overall (653/952, 68.6%)	1.13	0.97-1.32	0.126
Acute respiratory failure
No (424/668, 63.5%)	1.13	0.94-1.37	0.200	0.907
Yes (229/284, 80.6%)	1.15	0.89-1.49	0.297
Hemodynamic instability
No (481/754, 63.8%)	1.08	0.90-1.29	0.400	0.425
Yes (172/198, 86.9%)	1.27	0.94-1.71	0.127
Major surgery
No (507/668, 75.9%)	1.19	1.00-1.42	0.048	0.286
Yes (146/284, 51.4%)	0.99	0.72-1.37	0.950
Acute heart failure
No (540/788, 68.5%)	1.16	0.98-1.37	0.095	0.588
Yes (113/164, 68.9%)	1.02	0.70-1.47	0.922
Massive bleeding
No (559/840, 66.6%)	1.13	0.96-1.34	0.146	0.938
Yes (94/112, 83.9%)	1.10	0.74-1.66	0.634
Sepsis
No (319/537, 59.4%)	1.02	0.82-1.27	0.850	0.128
Yes (334/415, 80.5%)	1.29	1.04-1.60	0.021
Nephrotoxins exposure
No (585/869, 67.3%)	1.11	0.94-1.30	0.227	0.447
Yes (68/83, 81.9%)	1.33	0.82-2.16	0.243
Hypotension (MAP < 65 mmHg or inotrope/vasopressor usage)
No (153/292, 52.4%)	0.95	0.69-1.30	0.735	0.190
Yes (500/660, 75.8%)	1.21	1.02-1.44	0.034
CKD (baseline eGFR < 60)
No (311/463, 67.2%)	1.18	0.95-1.48	0.142	0.486
Yes (342/489, 69.9%)	1.07	0.87-1.33	0.510

ACEi, angiotensin-converting enzyme inhibitor; AKI, acute kidney injury; ARB, angiotensin-receptor blocker; CI, confidence interval; CKD, chronic kidney disease; eGFR, estimated glomerular filtration rate; HR, hazard ratio; ICU, intensive care unit; MAP, mean arterial pressure.