Acute kidney injury
Acute kidney injury (AKI) was mentioned as an outcome in nine out of the 11 comparative studies. The results are mixed, with several stating no difference in the rates of AKI seen between the two groups2,20,44-49, one study reporting a significant decrease in AKI in the non-Witness group50 and two studies showing a significant decrease in AKI for Witnesses15,51. The range of patients with postoperative AKI in the comparative studies was large (0 to 73.3% for Witnesses and 0 to 77.8% for the non-Witness group). Two of the non-comparative studies found varying rates of AKI among Witnesses, with one study reporting it in 2.5% of patients4, whereas Duce et al. , which compared outcomes for Witnesses given EPO pre operatively to those not given EPO, found AKI rates to be 47.17% and 41.51%, respectively8. The wide difference in rates reported may be accounted for by the varying definition of AKI used and the vast array in type of surgeries carried out in different studies, which makes it problematic to form any definitive conclusion concerning the risk of AKI in Witnesses following cardiac surgery.