Abnormal Ankle-Brachial Index and Risk of Cardiovascular and all-cause mortality in Patients with Chronic Kidney Disease: An Updated Systematic Review and Meta-analysis.

Background: Chronic kidney disease (CKD) is a global health concern associated with an elevated risk of cardiovascular (CV) and all-cause mortality. The ankle-brachial index (ABI), a non-invasive diagnostic tool, is widely recognized for detecting peripheral arterial disease (PAD). This meta-analysis aims to assess whether abnormally low or high ABI values independently predict CV and all-cause mortality in CKD patients, including those on hemodialysis.

Methods: A systematic review and meta-analysis was conducted following PRISMA guidelines, using PubMed, Cochrane, and Google Scholar databases through September 2024 to identify studies on abnormal ABI and mortality outcomes in CKD patients with or without hemodialysis. Data was analyzed with random-effects models, and subgroup analyses evaluated variations by patient characteristics, region, sample size, and follow-up duration.

Results: The analysis included ten cohort studies comprising 13,378 participants. ABI values between 0.9 and 1.3 were defined as normal. Individuals with abnormally low ABI (<0.9) demonstrated a significantly higher incidence in CV mortality (HR = 2.23; CI: 1.75-2.83) and all-cause mortality (HR = 1.78; CI: 1.55-2.05). Those with high ABI ≥1.3 were associated with a 2.77-fold increase in CV mortality (HR = 2.77; CI: 1.74-4.41) and a 1.49 higher risk of all-cause mortality (HR = 1.49; CI: 1.09-2.02). Overall, abnormal ABI values were linked to a 1.74 higher risk of all-cause mortality (HR = 1.74; CI: 1.54-1.96) and a 2.34-fold increase in CV mortality (HR = 2.34; CI: 1.93-2.85). Subgroup analyses revealed higher mortality risks in hemodialysis patients compared to non-dialysis CKD patients and in studies conducted in Asia.

Conclusion: Abnormal ABI values show a U-shaped relationship with mortality, serving as strong predictors of CV and all-cause mortality in CKD patients, particularly those on hemodialysis. Since CV and all-cause mortality is high in CKD patients, these findings suggest that ABI measurement is a useful screening technique to assist prognosticate such patients. Further studies are warranted to validate these findings and to better understand the prognostic utility of ABI across different CKD stages, including both dialysis-dependent and non-dialysis CKD patients.