Chronic kidney disease and dementia incidence in England

Takeaway

• This study found a co-occurrence of detection of chronic kidney disease (CKD) and dementia in the first 6 months after CKD detection, while a weak association was seen in the long run.
• No graded association was seen between the CKD stage and the incidence of dementia diagnosis.
• A strong association was found between CKD stage and all-cause mortality.

• Findings warrant further studies to independently determine whether better management of risk factors in patients with CKD may reduce the impact on cognitive impairment and the observed long-term associations with dementia.

Study design

• This cohort study included 235,004 participants with CKD and 233,395 matched participants without CKD (mean age 75.4±9.7 years, 39.3% male) using data from the Clinical Practice Research Datalink (2004 to 2014).
• Primary outcome: first-ever diagnosis of dementia; secondary outcome: all-cause mortality.
• Funding: None disclosed.

• During a median follow-up of 3.0 years, 20658 participants were newly diagnosed with dementia (11973 in the CKD cohort; 8685 in the matched comparison cohort).
• The crude incidence rate of dementia was 11.4 and 9.4 per 1000 person-years in matched patients with and without CKD, respectively.
• CKD status was associated with an incident dementia diagnosis in the first 6 months of the follow-up (adjusted rate ratio [aRR], 1.58; 95% CI, 1.44-1.74), however, this association was weaker after 6 months (aRR, 1.12; 95% CI, 1.08-1.16).
• No significant association was seen between CKD stage and incident dementia diagnosis in patients with CKD.
  • Compared with CKD stage 3a, the aRR was 1.04 for CKD stage 3b and 0.94 for CKD stages 4/5 in the first 6 months, while it was 0.97 and 0.89 from 6 months onwards.
• Compared with patients with CKD stage 3a, the aRR for all-cause mortality was:
  • First 6 months:
    • CKD stages 3b: 1.85 (95% CI, 1.74-1.95),
    • CKD stage 4/5: 4.33 (95% CI, 4.06-4.61).
  • After 6 months of follow-up:
    • CKD stage 3b: 1.51 (95% CI, 1.48-1.54),
    • CKD stage 4/5: 2.56 (95% CI, 2.47-2.63).

• The crude incidence rate of dementia might be underestimated.