Incidence and associations of acute kidney injury after major abdominal surgery

Purpose: Acute kidney injury (AKI) is a recognised risk factor for adverse outcomes in critical illness and hospitalised patients in general. To understand the incidence and associations of AKI as a peri-operative complication of major abdominal surgery, we conducted a systematic literature review and meta-analysis. Methods: Using a systematic strategy, we searched the electronic reference databases for articles describing post-operative renal outcomes using consensus criteria for AKI diagnosis (RIFLE, AKIN or KDIGO) in the setting of major abdominal surgery. Pooled incidence of AKI and, where reported, pooled relative risk of death after post-operative AKI were estimated using random effects models. Results: From 4287 screened titles, 19 articles met our inclusion criteria describing AKI outcomes in 82,514 patients undergoing abdominal surgery. Pooled incidence of AKI was 13.4 % (95 % CI 10.9-16.4 %). In eight studies that reported the short-term mortality, relative risk of death in the presence of post-operative AKI was 12.6 fold (95 % CI, 6.8-23.4). Where reported, length of stay was greater and non-renal post-operative complications were also more frequent in patients experiencing AKI. Conclusions: Using modern consensus definitions, AKI is a common complication of major abdominal surgery that is associated with adverse patient outcomes including death. While a causative role for AKI cannot be concluded from this analysis, as an important signal of peri-operative harm, AKI should be regarded as an important surgical outcome measure and potential target for clinical interventions.