Association Rules Mining and Prognostic Stratification of 2-Year Longevity in Octogenarians Undergoing Endovascular Therapy for Lower-extremity Arterial Disease: Observational Cohort Study (Preprint)

BACKGROUND Two-year longevity (2YL) is a crucial consideration in revascularization strategies for patients with symptomatic lower-extremity artery disease (LEAD). However, factors associated with 2YL and risk stratification in octogenarians or nonagenarians have been underreported. OBJECTIVE We aimed to investigate the associated variables and stratify the 2-year prognosis in elderly patients with LEAD. METHODS We performed logistic regression and association rules mining based on the Apriori algorithm to discover the independent variables and validate their associations with 2YL. Malnutrition, inflammation, and stroke (MIS) factors were identified. C-statistics and Kaplan-Meier analysis were used to assess the impact on 2YL of different numbers of MIS factors. RESULTS We recruited a total of 232 octogenarians or nonagenarians (mean age 85±4.2 years) treated with endovascular therapy. During the study period, 81 patients died (33% from a cardiac origin) within two years. Association rules analysis showed the interrelationships between neutrophil-lymphocyte ratio (NLR) and nutritional status, determined by the Controlling Nutritional Status (CONUT) score or Geriatric Nutritional Risk Index (GNRI), with 2YL. The cut-off values of NLR, GNRI, and CONUT were ≥3.89, ≤90.3, and >3, respectively. The C-statistics for the predictive power for 2YL were similar between the CONUT score and GNRI-based models (0.773 vs. 0.760, P=0.572). The Kaplan-Meier analysis showed that 2YL was worse, as the number of MIS factors increased either in the GNRI-based model (92% vs. 68% vs. 46% vs. 12%, P<0.001) or the CONUT score model (87% vs. 75% vs. 49% vs. 10%, P<0.001). The hazard ratio between those with three factors and those without was 18.2 (95% confidence interval [CI]: 7.0-47.2, P<0.001) in the GNRI and 13.6 (95% CI: 5.9-31.5, P<0.001) in the CONUT score models. CONCLUSIONS This study demonstrated the association and crucial role of MIS factors in assessing 2YL in elderly patients with LEAD. Using this simple risk score might assist clinicians in selecting the appropriate treatment. CLINICALTRIAL Not applicable.