Acute kidney injury and 1-year mortality after colorectal cancer surgery: a population-based cohort study

OBJECTIVES: Acute kidney injury (AKI) is a frequent postoperative complication, but the mortality impact within different postoperative time frames and severities of AKI are poorly understood. We examined the occurrence of postoperative AKI among colorectal cancer (CRC) surgery patients and the impact of AKI on mortality during 1 year after surgery. DESIGN: Observational cohort study. We defined the exposure, AKI, as a 50% increase in plasma creatinine or initiation of renal replacement therapy within 7 days after surgery or an absolute increase in creatinine of 26 µmol/L within 48 hours. SETTING: Population-based Danish medical databases. PARTICIPANTS: A total of 6580 patients undergoing CRC surgery in Northern Denmark during 2005–2011 were included from the Danish Colorectal Cancer Group database. OUTCOMES MEASURE: Occurrence of AKI and 8–30, 31–90 and 91–365 days mortality in patient with or without AKI. RESULTS: AKI occurred in 1337 patients (20.3%) of the 6580 patients who underwent CRC surgery. Among patients with AKI, 8–30, 31–90 and 91–365 days mortality rates were 10.1% (95% CI 8.6% to 11.9%), 7.8% (95% CI 6.4% to 9.5%) and 12.0% (95% CI 10.3% to 14.2%), respectively. Compared with patients without AKI, AKI was associated with increased 8–30 days mortality (adjusted HR (aHR)=4.01,95% CI 3.11 to 5.17) and 31–90 days mortality (aHR 2.08,95% CI 1.60 to 2.69), while 91–365 days aHR was 1.12 (95% CI 0.89 to 1.41). We observed no major differences in stratified analyses. CONCLUSIONS: AKI after surgery for CRC is a frequent postoperative complication associated with a substantially increased 90-day mortality. AKI should be considered a potential target for reducing 90-day mortality.