Association of systemic immune-inflammation index (SII) with 28-day all-cause mortality in acute heart failure: A retrospective cohort study.

Higher SII tertiles were independently associated with greater 28-day all-cause mortality in AHF patients.

• Compared with the lowest tertile, the middle SII tertile had HR = 1.485 (95% CI: 1.193–1.849, P < .01)
• The highest SII tertile had HR = 2.497 (95% CI: 2.060–3.028, P < .01)
• Associations were assessed using multivariable Cox proportional hazards models adjusting for demographic, clinical, and laboratory covariates
• Kaplan-Meier analysis showed significant differences in 28-day mortality across SII tertiles (log-rank P < .001)

SII demonstrated a dose-response relationship with 28-day mortality in AHF patients.

• Restricted cubic spline analyses were used to evaluate the shape of the association
• Results suggested a dose-response (non-linear or continuous) relationship between SII and 28-day mortality
• SII was calculated as (platelet count × neutrophil count)/lymphocyte count from initial admission laboratory values

Elevated SII was similarly associated with increased mortality at 90-, 180-, and 365-day follow-up timepoints.

• Similar associations were observed for 90-, 180-, and 365-day mortality beyond the primary 28-day endpoint
• This suggests SII has prognostic relevance beyond the acute 28-day period
• The study used a retrospective cohort design from the MIMIC-IV database

Adding SII to established severity scores improved discrimination for 28-day mortality.

• Adding SII to Acute Physiology Score III (APS III) and Sequential Organ Failure Assessment (SOFA) improved discrimination for 28-day mortality
• Improvement was assessed using receiver operating characteristic (ROC) analyses
• This suggests SII provides incremental prognostic value beyond standard ICU severity scores

The study included 5482 AHF patients admitted to the ICU, identified from the MIMIC-IV database.

• A total of 5482 patients were included in the final analysis
• Inclusion criteria required an AHF diagnosis on first ICU admission
• Exclusion criteria included ICU stays < 24 hours or missing key laboratory data
• Patients were categorized into tertiles based on their SII values