A nomogram based on the value of the dynamic evolution of systemic immune inflammatory index in the evaluation of severe heatstroke.

Background: Severe heatstroke patients have a poor prognosis. There are few descriptions of the inflammatory response to heatstroke in clinical studies. Systemic immune-inflammation index(SII) is a new index to reflect the inflammatory state of disease.

Methods: This retrospective observational study included patients who had severe heatstroke between 2010 and 2023. Multivariate logistic regression and nomogram were performed to determine the ability of the SII to predict the prognosis of these patients, and subgroup analysis was performed according to SII levels.

Results: Of the 177 patients included in our study, 28 (15.8%) died. There was no difference in SII values between the first day (p = 0.810) and the second day (p = 0.184) in multivariate analysis. The SII value of the third day (SII 72) was elevated in patients with heatstroke who died compared to that in those who survived (p = 0.035). In multivariable logistic regression, Sequential Organ Failure Assessment (SOFA) score (OR = 1.717, 95%CI: 1.073-2.747, p = 0.024) and SII 72 (OR = 1.001, 95%CI: 1.000-1.002, p = 0.035) were found to be independent predictors of mortality. SII 72 combined with SOFA score distinguished between patients who died and those who survived better than did the separate SOFA score. Patients with SII 72 > 1000 had poor clinical prognosis.

Conclusions: Compared to SII results from the first and second days, third-day results more meaningfully predict poor heatstroke prognosis. SII 72 may be a good indicator, and when combined with SOFA, offers enhanced predictive value.