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

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. 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. 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. AKI stage 3 is independently associated with hyperactive delirium. Further research is required to explore the factors that contribute to this association.