Supplementary file 1_Association between the alkaline phosphatase-to-albumin ratio and recorded early all-cause mortality within 90 days of admission in patients with heart failure: a retrospective cohort study in a Chinese population.docx

In the complete-case model (n = 1,824; 36 deaths), each 1-SD increase in ln(APAR) was associated with higher mortality (HR 1.375, 95% CI 1.024–1.846; P = 0.034), whereas raw APAR per 1 U/g was not (HR 1.146, 95% CI 0.988–1.330; P = 0.072). The spline showed an overall association (P = 0.025) and nonlinearity (P = 0.023). Nine of 37 deaths were confirmed in-hospital.

Among 1,897 patients discharged without recorded in-hospital death, 28 died within 90 days: 15 on a later calendar date, 12 on the discharge date, and one with missing exact timing. In the strict post-discharge analysis, the adjusted HR was 1.460 (95% CI 0.931–2.289; P = 0.099; 15 events). APAR showed modest discrimination (AUC 0.698), while incremental value was limited: ΔC-index 0.018 (P = 0.104), IDI 0.0019 (95% CI −0.0035 to 0.0252), small decision-curve gains, and continuous NRI 0.179 (95% CI −0.129 to 0.577).</p>Conclusion<p>Higher admission ln(APAR) was associated with recorded early all-cause mortality within 90 days of admission, but the association was modest, nonlinear, scale-dependent, and based on few events.

Post-discharge estimates were directionally consistent but imprecise. External validation is required before APAR or any cutoff is used for clinical risk stratification.</p>