Therapeutic hypothermia and prevention of acute kidney injury: a meta-analysis of randomized controlled trials

Background

Therapeutic hypothermia has been shown to reduce neurological morbidity and mortality in the setting of out-of-hospital cardiac arrest and may be beneficial following brain injury and cardiopulmonary bypass. We conducted a systematic review to ascertain the effect of therapeutic hypothermia on development of acute kidney injury (AKI) and mortality.

Methods

We searched for randomized controlled trials in MEDLINE through February 2011. We included trials comparing hypothermia to normothermia that reported kidney-related outcomes including, development of AKI, dialysis requirement, changes in serum creatinine, and mortality. We performed Peto fixed-effect and random-effects model meta-analyses, and meta-regressions.

Results

Nineteen trials reporting on 2218 patients were included; in the normothermia group, the weighted rate of AKI was 4.2%, dialysis requirement 3.7%, and mortality 10.8%. By meta-analysis, hypothermia was not associated with a lower odds of AKI (odds ratio OR] 1.01, 95% confidence interval CI] 0.68, 1.51; P = 0.95) or dialysis requirement (OR 0.81; 95% CI 0.30, 2.19; P = 0.68); however, by meta-regression, a lower target cooling temperature was associated with a lower odds of AKI (P = 0.01). Hypothermia was associated with lower mortality (OR 0.69; 95% CI 0.51, 0.92; P = 0.01).

Conclusions

In trials that ascertained kidney endpoints, therapeutic hypothermia prevented neither the development of AKI nor dialysis requirement, but was associated with lower mortality. Different definitions and rates of AKI, differences in mortality rates, and concerns about the optimal target cooling temperature preclude definitive conclusions.