Systemic Immune‐Inflammation Index and Serum Uric Acid for Predicting Short‐Term Delivery in Women With Threatened Preterm Labor
Mustafa Hakan Acer, Mustafa Şanlı, Hilal ÖzbekABSTRACT
Problem
This study evaluated the independent and combined predictive value of the systemic immune‐inflammation index (SII) and serum uric acid for short‐term delivery in women hospitalized with threatened preterm labor.
Study Design
This retrospective cohort study included women hospitalized with threatened preterm labor between January 2020 and December 2025. Receiver operating characteristic (ROC) curve analysis assessed the predictive performance of SII and serum uric acid for delivery within 48 h and 7 days. Multivariable logistic regression models were adjusted for clinically relevant covariates. Internal validation was performed using 1000 bootstrap resamples, with Firth penalized models used for the 48‐h outcome because of separation during resampling.
Results
Among 621 women, 51 (8.2%) delivered within 48 h and 239 (38.5%) within 7 days. SII and serum uric acid levels were significantly higher in women who delivered within both time intervals (all p < 0.001). SII showed numerically higher AUCs than serum uric acid for delivery within 48 h (0.932 vs 0.876) and within 7 days (0.882 vs 0.843); however, paired DeLong tests did not demonstrate statistically significant differences ( p = 0.0686 and p = 0.0504, respectively). Both biomarkers remained independently associated with delivery within 48 h in multivariable Firth penalized logistic regression and within 7 days in standard maximum‐likelihood logistic regression. Observed delivery proportions increased stepwise across the combined biomarker categories.
Conclusion
SII and serum uric acid were independently associated with short‐term delivery. Their combined assessment may provide additional information for short‐term risk stratification using routinely available laboratory tests. External validation is required before clinical implementation.