Table 1.
Clinical studies investigating the association between acute kidney injury and delirium
| Author(s) | Year | Methodology | AKI criteria | Strengths/Limitations | Conclusion |
|---|---|---|---|---|---|
| Wan et al. | 2019 |
Case–control study 142 cases, 142 controls |
KDIGO |
Strengths: Matched case–control design using prevalent cases over a 1-year period. 97% specific for method to detect hyperactive delirium Limitations: Single-center study. Retrospective design limited to data recorded in electronic health records |
AKI stage 3 is associated with hyperactive delirium (OR 5.40, 95% CI 2.33–12.51). AKI stages 1 and 2 were not independently associated with hyperactive delirium |
| Pisani et al. | 2007 | Prospective cohort (n = 304) | Serum creatinine level > 2 mg/dL |
Strengths: At the time, the largest collection of data on delirium among older ICU patients. First to examine admission risk factors Limitations: Missing data on risk factors, specifically liver function test and arterial pH. Lack of generalization to younger population. Acute vs. chronic serum creatinine level > 2 was not distinguished as being associated with delirium |
Serum creatinine level of > 2 mg/dL is an admission risk factor for delirium (OR 2.1, 95% CI 1.1–4.0) |
| Siew et al. | 2017 | Prospective cohort (n = 466) | KDIGO |
Strength: Large sample size and prospective design. Findings persisted when using an alternative definition for AKI Limitations: Single-center population. Excluded patients with overt neurologic disorders. Did not have preadmission kidney function on all patients |
AKI stage 2 (OR 1.55; 95% CI, 1.07–2.26) and stage 3 (OR 2.56; 95% CI, 1.57–4.16) are associated with delirium. AKI stage 1 was not significantly associated with delirium (OR 1.13, 95% CI 0.91–1.41) |
| Zipser et al. | 2019 | Prospective cohort (n = 1487) | Medical diagnoses data retrieved from the electronic medical chart (Klinikinformationssystem, KISIM, CisTec AG, Zurich) described as diagnostic clusters according to the 10th revision of the International Classification of Diseases (ICD-10) |
Strength: Systemically assessed predisposing and precipitating factors for delirium. Ample sample size Limitations: Selection of delirium-relevant ICD-10 codes chosen. Not all codes could be included and information may be skewed or lost in this process |
AKI is associated with delirium (OR 10.01, CI 1.13–88.73, p = 0.039). Chronic kidney disease is not associated with delirium (OR 1.04, CI 0.61–1.78, p = 0.891) |
| Jäckel et al. | 2021 | Retrospective cohort (n = 919) | KDIGO |
Strength: Adjusted for confounders of delirium thereby reducing bias Limitations: Used NuDesc to define delirium, hence definition not congruent to DSM-5 definition. Retrospective study. Baseline kidney functions not determined in all cases |
Delirium is independently predicted by AKI stage 2/3 (OR 1.69, CI 1.04–2.73, p = 0.033) |
AKI, Acute kidney injury; OR, odds ratio; CI, confidence interval; KDIGO, Kidney Disease: Improving Global Outcomes; and HR, hazards ratio