Effects of acute kidney injury and chronic kidney disease on long-term mortality after coronary artery bypass grafting.
BACKGROUND
Both acute kidney injury (AKI) and chronic kidney disease (CKD) are important issues in patients undergoing coronary artery bypass grafting (CABG), particularly with regard to mortality. However, their synergistic or discrete effects on long-term mortality remain unresolved.


METHODS
A total of 1,899 patients undergoing CABG were retrospectively analyzed. The adjusted hazard ratios for all-cause mortality were calculated after stratifying the timeframes. To evaluate the synergistic effects between AKI and CKD, the relative excess risk due to interaction was applied.


RESULTS
The presence of AKI, CKD, or both increased the hazard ratios for mortality, compared with the absence of both: AKI alone, 1.84 (1.464-2.319); CKD alone, 2.46 (1.735-3.478); and AKI and CKD together, 3.21 (2.301-4.488). However, the relationships with mortality were different between AKI and CKD, according to the timeframes: AKI primarily affected early mortality, particularly within 3 years, whereas CKD had a relatively constant effect on both the early and late periods. When the parameters from the relative excess risk due to interaction were obtained, there was a synergistic additive effect on early mortality between AKI and CKD.


CONCLUSIONS
The relationships with mortality after CABG were different between AKI and CKD. However, their effects were not exclusive but synergistic.
Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.
Seung Seok
SS
Han
Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.
Nara
N
Shin
Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Seon Ha
SH
Baek
Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Shin Young
SY
Ahn
Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.
Dong Ki
DK
Kim
Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Sejoong
S
Kim
Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Ho Jun
HJ
Chin
Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Dong-Wan
DW
Chae
Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea. Electronic address: kyna@snubh.org.
Ki Young
KY
Na
D058186:Acute Kidney Injury / Q000453:epidemiology*; D000368:Aged; D001026:Coronary Artery Bypass / Q000401:mortality*; D003327:Coronary Disease / Q000453:epidemiology* / Q000401:mortality / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D012372:ROC Curve; D051436:Renal Insufficiency, Chronic / Q000453:epidemiology*; D016019:Survival Analysis