Incidence of acute kidney injury in cancer patients: a Danish population-based cohort study.

BACKGROUND: Cancer patients may be at increased risk of acute kidney injury, but evidence is limited.
METHODS: We assembled a cohort of incident cancer patients diagnosed within a population-based hospital setting in Northern Denmark (population:~1.2 million) between 1999 and 2006. Patients were followed up to five years for acute kidney injury, identified using creatinine measurements recorded in a laboratory database covering the study area. Acute kidney injury was defined according to recent consensus criteria as a 50% increase in creatinine level. We computed incidence rate, 1-year, and 5-year risks of acute kidney injury, accounting for competing risk from death. Acute kidney injury incidence was compared between cancers using a Cox regression model adjusted for important confounders.
RESULTS: Among 37,267 incident cancer patients with a creatinine measurement, 9613 (25.8%) developed acute kidney injury during 77,376 person-years. The incidence was 258 (95%CI: 252-264) per 1000 person-years the first year after cancer diagnosis decreasing to 43 (95%CI: 41-44) thereafter. The 1-year risk was 17.5% (95%CI: 17.1-17.9%), and the 5-year risk was 27.0% (95%CI: 26.5-27.5%). We observed the highest 1-year risk in patients with kidney cancer [44.0% (95%CI: 40.5-47.5)], liver cancer [33.0% (95%CI: 28.2-37.8%)], or multiple myeloma [31.8% (95%CI: 27.3-36.3%)]. Similar results were observed after adjustment for confounders. Both overall and for most specific cancer sites, risks were higher among patients with distant metastases at cancer diagnosis.
CONCLUSION: Acute kidney injury is a common complication in cancer patients, particularly in patients with kidney cancer, liver cancer, or multiple myeloma.