Acute kidney injury as a risk factor of hyperactive delirium: A case control study.

PURPOSE: Delirium and acute kidney injury (AKI) are common organ dysfunctions during critical illness. Both conditions are associated with serious short- and long-term complications. We investigated whether AKI is a risk factor for hyperactive delirium. METHODS: This was a single-centre case control study conducted in a 30 bedded mixed Intensive Care Unit in the UK. Hyperactive delirium cases were identified by antipsychotic initiation and confirmation of delirium diagnosis through validated chart review. Cases were compared with non-delirium controls matched by Acute Physiology and Chronic Health Evaluation II score and gender. AKI was defined by the KDIGO criteria. RESULTS: 142 cases and 142 matched controls were identified. AKI stage 3 was independently associated with hyperactive delirium [Odds ratio (OR) 5.40 (95% confidence interval (CI) 2.33-12.51]. Other independent risk factors were mechanical ventilation [OR 2.70 (95% CI 1.40-5.21)], alcohol use disorder [OR 5.80 (95% CI 1.90-17.72)], and dementia [OR 9.76 (95% CI 1.09-87.56)]. Hospital length of stay was significantly longer in delirium cases (29 versus 20 days; p = .004) but hospital mortality was not different. CONCLUSIONS: AKI stage 3 is independently associated with hyperactive delirium. Further research is required to explore the factors that contribute to this association.