Does AKI After Cardiac Surgery Increase Mortality Risk?

Acute kidney injury (AKI) after cardiac surgery increases the risk of mortality over the first 5 years following surgery, according to a recent study. However, this risk decreases and vanishes after 5 years.

Past research has indicated that AKI in cardiac surgery is related to complications, early and late mortality, and increased health care costs. However, little data exists on the overall impact of AKI on mortality during long-term follow-up.
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In their study, the researchers evaluated a total of 7075 adults admitted for cardiac surgery. Follow-up data were obtained either from the National Mortality Registry or through a telephone survey during the 1 year, 5 years, 10 years, and 15 years following surgery.

The researchers assessed all-cause mortality at 5 different time intervals: 30 days to 1 year post-surgery, 1 to 3 years post-surgery, 3 to 5 years post-surgery, 5 to 10 years post-surgery, and 10 to 15 years post-surgery.

Cox proportional hazard regression models were performed during each period to adjust for mortality related to comorbidity and pre-operative, intra-operative and postoperative variables.

Results showed that 36.1% of participants developed AKI. However, the researchers found that AKI was an independent predictor of death only during the first 5 years post-surgery.

The only factors related to increased mortality risk over the entire follow-up period were age and the presence of diabetes mellitus and/or congestive heart failure (CHF).

“Our study demonstrates a transient association of AKI with long-term mortality that progressively decreases and vanishes 5 years after surgery,” the researchers concluded. “The knowledge of this dynamic is crucial to understanding this complex association, planning health care and allocating resources.”

—Christina Vogt

Reference:

Ferreiro A, Lombardi R. Acute kidney injury after cardiac surgery is associated with mid-term but not long-term mortality: a cohort-based study [Published online July 10, 2017]. PLOS One. doi:10.1371/journal.pone.0181158.