Introduction
Cardiorenal syndrome type 1 (CRS-1) reflects an abrupt worsening in cardiac function
leading to acute kidney injury (AKI). Acute cardiac conditions contributing to CRS-1
include acute heart failure (AHF), acute coronary syndrome (ACS) and cardiac surgery
(CS). The objective of this study was to evaluate the epidemiology of AKI in CRS-1.
Methods
This is a systematic review and meta-analysis. AKI defined by the RIFLE definition
and its modifications AKIN and KDIGO is grouped as AKIRIFLE. Similarly, AKI defined
by variations of worsening renal failure is grouped as AKIWRF. Incidence of AKI is
reported by the different definitions of AKI. In addition, we report on mortality
and length of intensive care and hospital stay (LOSICU and LOShosp) for AKIRIFLE.
Data are reported as percentage, risk ratio (RR), and mean difference (MD).
Results
Our literature search yielded 316 potential papers, of which 57 were included (20
papers on AHF, 15 ACS and 22 Cs). A risk of bias analysis showed a low risk for selection
bias in 55% of the studies and prospective data collection in 45%. AKIRIFLE was used
in 33 studies (RIFLE in 22, AKIN in 14, KDIGO in four), AKIWRF, with six variants,
in 24 studies and use of RRT (AKIRRT) in 20 studies. The incidence of AKI in CRS-1
patients defined by AKIRIFLE and AKIWRF was similar (22.5%, respectively 22.4%, P
= 0.401), and greater than AKIRRT (2.6%, both P < 0.001). AKIRIFLE occurred more frequently
in AHF patients compared with ACS and CS patients (55.0% vs. 14.9% vs. 19.3%; P =
0.009 respectively P = 0.001, P = NS for ACS vs. CS). This was similar when defined
by AKIWRF. AKIRRT was evenly distributed among CRS- 1 subtypes (AHF 4.3%, ACS, 1.7%,
and CS 3.1%, P = 0.611). Despite predominant low severity of AKIRIFLE (stage 1: 16.9%,
stage 2: 3.7%, and stage 3: 3.6%), AKIRIFLE was associated with increased mortality
(RR = 5.4), LOSICU (MD 1.7 days), and LOShosp (MD 4.4 days), and increasing AKIRIFLE
severity was associated with increase in these three outcomes in all CRS-1 patients
as well as in the three subgroups. The impact of AKIRIFLE on mortality was greatest
in CS patients (AHF RR = 2.8, ACS RR = 3.5, and CS RR = 9.1). Not surprisingly, AkIWRF
had similar impact on outcomes, but AKIRRT had greater impact compared with AKIRIFLE
(mortality RR = 9.16, LOSICU MD = 10.6 days, and LOShosp, MD = 20.2 days).
Conclusion
Almost one-quarter of patients with an acute cardiac condition had AKI, and RRT was
used in approximately 3%. AKI was associated with significant worse outcomes. AHF
patients experienced the highest incidence of AKI, but the impact on mortality was
greatest in CS patients.