Higher systemic immune-inflammation index associated with increased mortality in interstitial lung disease

A retrospective cohort study investigated the association between the systemic immune-inflammation index (SII) and all-cause mortality in 366 patients with interstitial lung disease (ILD). The median follow-up was 20.6 months. The primary outcome was all-cause mortality, which occurred in 91 patients (24.9%). The study did not report a specific comparator group.

The main results showed that median SII was higher in deceased patients (1471.14) compared to survivors (1017.21). The SII demonstrated a statistically significant discriminatory ability for mortality, with an area under the curve (AUC) of 0.658 (95% CI 0.594–0.723). Survival was significantly lower in the high SII group compared to the low SII group (log-rank p < 0.001). No effect sizes for mortality risk were reported.

Safety and tolerability data were not reported. The study has several key limitations: it is a retrospective observational study, which establishes association but not causation. The generalizability is unclear as the clinical setting was not reported. The funding sources and potential conflicts of interest were also not reported.

For clinical practice, this study identifies a potential prognostic biomarker in ILD. However, the SII's clinical utility for risk stratification or guiding therapy remains unproven. The findings should be interpreted as hypothesis-generating, requiring validation in prospective studies before any consideration for integration into clinical decision-making.