Long-term risk of dementia following acute kidney injury: A population-based study

Acute Kidney Injury and Its Association With Dementia and Specific Dementia Types: Findings From a Population-Based Study in Sweden

BACKGROUND AND OBJECTIVES

Preclinical studies suggest that acute kidney injury (AKI) results in biochemical and pathologic changes in the brain. We aimed to explore the association between experiencing AKI and subsequent risks of developing dementia.

METHODS

We conducted a study involving individuals aged 65 years and older in Stockholm from 2006 to 2019, who were free from dementia diagnosis and had data on kidney function. The exposure was an episode of AKI (time varying), ascertained by issued clinical diagnoses and transient creatinine elevations according to Kidney Disease Improving Global Outcomes criteria. The outcome was all-cause dementia and specific types of dementia, ascertained by clinically confirmed cases in the Swedish registry of cognitive/dementia disorders, the presence of 2 issued dementia diagnoses in outpatient care, or initiation of specific antidementia medications. We investigated associations with dementia through Cox proportional hazard regression by AKI, severity levels of AKI, AKI recurrence, and setting (community-acquired or hospital-acquired AKI).

RESULTS

We included 305,122 individuals with a median age of 75 ± 8 years (56.6% women). During a median follow-up of 12.3 (interquartile range 8.7-13.3) years, there were 79,888 individuals (26%) suffering from at least 1 episode of AKI and 47,938 incident cases (16%) of dementia. The rate of dementia cases was 37.0 per 1,000 person-years (95% CI 36.2-37.8) after developing AKI, which was approximately 2 times higher than the rate observed during the periods before AKI (17.3, 95% CI 17.2-17.5). After multivariable adjustment, developing AKI was associated with a 49% higher rate of subsequent dementia (adjusted hazard ratio hazard ratio [HR] 1.49, 95% CI 1.45-1.53). This pattern was consistent across dementia types, with HRs of 1.88 (95% CI 1.53-2.32), 1.47 (1.38-1.56), and 1.31 (1.25-1.38) for dementia with Lewy bodies and Parkinson disease with dementia, vascular dementia, and Alzheimer dementia, respectively. Risk associations were stronger in magnitude across more severe AKIs and in hospital-acquired vs community-acquired AKI.

DISCUSSION

Individuals who experienced an AKI were at increased risk of receiving a diagnosis of dementia.

Acute Kidney Injury, Systemic Inflammation, and Long-Term Cognitive Function: ASSESS-AKI

Key Points

This study highlights that AKI is associated with long-term cognitive decline. Soluble TNF receptor 1 concentrations seem to mediate a significant proportion of the risk of long-term cognitive impairment after AKI.

Background

Cognitive dysfunction is a well-known complication of CKD, but it is less known whether cognitive decline occurs in survivors after AKI. We hypothesized that an episode of AKI is associated with poorer cognitive function, mediated, at least in part, by persistent systemic inflammation.

Methods

Assessment, Serial Evaluation and Subsequent Sequelae of AKI enrolled patients surviving 3 months after hospitalization with and without AKI matched on the basis of demographics, comorbidities, and baseline kidney function. A subset underwent cognitive testing using the modified mini-mental status examination (3MS) at 3, 12, and 36 months. We examined the association of AKI with 3MS scores using mixed linear models and assessed the proportion of risk mediated by systemic inflammatory biomarkers.

Results

Among 1538 participants in Assessment, Serial Evaluation and Subsequent Sequelae of AKI, 1420 (92%) completed the 3MS assessment at 3 months and had a corresponding matched participant. Participants with AKI had lower 3MS scores at 3 years (difference −1.1 [95% confidence interval, −2.0 to −0.3] P = 0.009) compared with participants without AKI. A higher proportion of participants with AKI had a clinically meaningful (≥5 point) reduction in 3MS scores at 3 years compared with participants without AKI (14% versus 10%, P = 0.04). In mediation analyses, plasma-soluble TNF receptor-1 at 3 months after AKI mediated 35% (P = 0.02) of the AKI-related risk for 3MS scores at 3 years.

Conclusions

AKI was associated with lower 3MS scores, and Soluble TNF receptor 1 concentrations seemed to mediate a significant proportion of the risk of long-term cognitive impairment. Further work is needed to determine whether AKI is causal or a marker for cognitive impairment.

Harm! foul! How acute kidney injury SHReDDs patient futures

PURPOSE OF REVIEW

Transition from acute kidney injury (AKI) to chronic kidney disease (CKD) is increasingly accepted. Less well recognized, but supported by very similar data, is development of disease of other organ systems after AKI. Awareness of other-organ sequelae of AKI may inform efforts to improve the care of patients after AKI.

RECENT FINDINGS

Stroke, hypertension, reproductive risk, dementia, and death (SHReDD) are sequelae, which occur with increased risk relative to that of non-AKI within 6 months-3 years after AKI diagnosis, and which are supported by preclinical/mechanistic study. Adjusted hazard ratios for these sequelae are strikingly similar to that of AKI-CKD, ranging from 1.2 to 3.0. Mechanistic studies suggest kidney-centric mechanisms including sodium regulation, volume status regulation, and the renin-angiotensin system are drivers of long-term, extra-renal, change.

SUMMARY

Further clinical characterization and mechanistic insight is necessary, and may have considerable translational impact. Programs which screen or follow post-AKI patients may increase clinical utility if focus is expanded to include the SHReDD complications.

Association of Acute Kidney Injury with the Risk of Dementia: A Meta-Analysis

Acute kidney injury (AKI) is associated with several adverse outcomes, including new or progressive chronic kidney disease, end-stage kidney disease, and mortality. Epidemiological studies have reported an association between AKI and dementia as a long-term adverse outcome. This meta-analysis was aimed to understand the association between AKI and dementia risk. A literature search was performed in MEDLINE and Embase databases, from inception to July 2021, to identify epidemiological studies reporting the association between AKI and dementia risk. Title and abstract followed by the full-text of retrieved articles were screened, data were extracted, and quality was assessed, using the Newcastle-Ottawa scale by two investigators independently. The primary outcome was to compute the pooled risk of dementia in AKI patients. Subgroup analysis was also performed based on age and co-morbidities. Certainty of evidence was assessed using the GRADE approach. Statistical analysis was performed using Review Manager 5.4 software. Four studies (cohort (n = 3) and case-control (n = 1)) with a total of 429,211 patients, of which 211,749 had AKI, were identified. The mean age of the patients and the follow-up period were 64.15 ± 16.09 years and 8.9 years, respectively. Included studies were of moderate to high quality. The pooled estimate revealed a significantly higher risk of dementia in AKI patients with an overall relative risk/risk ratio (RR) of 1.92 (95% CI: 1.52-2.43), p ≤ 0.00001. Dementia risk increases by 10% with one year increase in age with an RR of 1.10 (95% CI: 1.09-1.11), p < 0.00001. Subgroup analysis based on stroke as a co-morbid condition also revealed significantly higher dementia risk in AKI patients (RR 2.30 (95% CI: 1.62-3.28), p = 0.009). All-cause mortality risk was also significantly higher in AKI patients with dementia with a pooled RR of 2.11 (95% CI: 1.20-3.70), p = 0.009. The strength of the evidence was of very low certainty as per the GRADE assessment. Patients with AKI have a higher risk of dementia. Further large epidemiological studies are needed to confirm the mechanistic association.

Acute kidney injury is associated with subtle but quantifiable neurocognitive impairments

BACKGROUND

Acute kidney injury (AKI) is associated with long-term morbidity and mortality. The effects of AKI on neurocognitive functioning remain unknown. Our objective was to quantify neurocognitive impairment after an episode of AKI.

METHODS

Survivors of AKI were compared to age-matched controls, as well as a convenience sample of patients matched for cardiovascular risk factors with normal kidney function (active control group). Patients with AKI completed two assessments, while the active control group completed one assessment. The assessment included a standardized test: The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), and a robotic assessment: Kinarm.

RESULTS

The cohort consisted of 21 patients with AKI, 16 of whom completed both assessments, and 21 active control patients. The majority of patients with AKI had Kidney Disease Improving Global Outcomes stage 3 AKI (86%), 57% received dialysis, and 43% recovered to ≤ 25% of their baseline serum creatinine by their first assessment. Compared to the RBANS, which detected little impairment, the Kinarm categorized patients as impaired in visuomotor (10/21, 48%), attention (10/20, 50%), and executive tasks (11/21, 52%) compared to healthy controls. Additionally, patients with AKI performed significantly worse in attention and visuomotor domains when compared to the active controls. Neurocognitive performance was generally not impacted by the need for dialysis or whether kidney function recovered.

CONCLUSION

Robotic technology identified quantifiable neurocognitive impairment in survivors of AKI. Deficits were noted particularly in attention, visuomotor, and executive domains. Further investigation into the downstream health consequences of these neurocognitive impairments is warranted.

Clinical features, risk factors, and clinical burden of acute kidney injury in older adults

Background: Few epidemiologic studies on acute kidney injury (AKI) have focused on the older adult population. This study investigated the clinical features, risk factors, and clinical burden in this population. Methods: A retrospective observational study was performed with the clinical data of inpatients at Guangdong Geriatrics Institute from 1 August 2012, to 31 December 2016. AKI was classified into community-acquired AKI (CA-AKI) and hospital-acquired AKI (HA-AKI), and the risk factors for AKI were ranked by weight. The relationships between AKI and adverse outcomes during hospitalization were analyzed using univariate and multivariate logistic regression. Results: In total, 6126 patients were enrolled, and 1704 patients developed AKI (27.8%): 6.3% had CA-AKI, and 21.5% had HA-AKI. In total, 1425 (23.3%), 202 (3.3%), and 77 (1.3%) patients had stage 1, 2 and 3 AKI, respectively. Age, dementia, moderate/severe renal disease, moderate/severe liver disease, metastatic solid tumor, female sex, congestive heart failure, chronic pulmonary disease, diabetes mellitus with chronic complications, non-metastatic tumor and lymphoma were independent risk factors for HA-AKI. The first five were also independent risk factors for CA-AKI. After multiple adjustment, AKI was associated with intensive care admission (CA-AKI: OR 5.688, 95% CI 3.122-10.361; HA-AKI: OR 4.704, 95% CI 3.023-7.298) and in-hospital mortality (CA-AKI: OR 5.073, 95% CI 2.447-10.517; HA-AKI: OR 13.198, 95% CI 8.133-21.419). Conclusion: AKI occurs in >25% of older adults in the geriatric ward. In addition to traditional risk factors, dementia and tumors were risk factors for AKI in older adults. AKI is closely related to a poor prognosis.