Association of Lok index with all-cause mortality among critically ill patients suffering from coronary artery disease: a cohort study based on MIMIC database

BMC Cardiovasc Disord. 2026 Jul 7. doi: 10.1186/s12872-026-06194-w. Online ahead of print.

ABSTRACT

BACKGROUND: The Lok index is a composite laboratory marker derived from the international normalized ratio (INR), the aspartate aminotransferase/alanine aminotransferase (AST/ALT) ratio, and platelet count. In critically ill patients, this index may reflect not only hepatic dysfunction but also coagulation disturbances, hematologic imbalances, and overall systemic illness burden. However, the association between the Lok index and mortality risks in critically ill patients with coronary artery disease (CAD) remains poorly understood. This study aims to assess the association between the Lok index and short- and long-term all-cause mortality (ACM) risks in this population.

METHODS: Relevant data were extracted from the MIMIC-Ⅳ (v3.1) database. Kaplan-Meier curves were generated based on the quartiles of the Lok index to compare ACM risks across groups, with differences assessed using the Log-Rank test. Restricted cubic spline (RCS) analysis and Cox proportional hazards models were employed to examine the association between the Lok index and ACM risks.

RESULTS: In total, 7,594 patients were included, with mortality rates of 20.71% at 30 days, 27.88% at 90 days, and 38.83% at 365 days. Across increasing Lok quartiles, absolute mortality increased progressively: from 16.01% to 27.28% at 30 days, from 22.17% to 35.65% at 90 days, and from 32.23% to 47.13% at 365 days. In the fully adjusted Cox model, when analyzed as a continuous variable, the Lok index was significantly associated with ACM risks at 365 days (HR = 1.011, 95% CI: 1.005-1.016, P < 0.001). When analyzed as a categorical variable, compared with Q1, a high Lok index (Q4) was significantly associated with ACM risks at 365 days (HR = 1.237, 95% CI: 1.107-1.381, P < 0.001). RCS analysis revealed a nonlinear relationship between the Lok index and mortality outcomes. Subgroup analyses, sensitivity analyses, and interaction tests confirmed the robustness of these associations.

CONCLUSION: In critically ill CAD patients, a higher Lok index is significantly associated with an elevated ACM risk at 30 days, 90 days, or 365 days, indicating that a higher Lok index is independently associated with both short- and long-term ACM risks. Nevertheless, given the modest per-unit effect size and the retrospective design, the Lok index should not be used in isolation to guide individual treatment decisions.

PMID:42414928 | DOI:10.1186/s12872-026-06194-w