Establishment of a predictive model for histological chorioamnionitis in patients with preterm premature rupture of membranes: a single center retrospective study

Objective: The aim of this study is to explore the risk factors for histological chorioamnionitis(HC) in patients with preterm premature rupture of membranes(PPROM), and further establish a simple and efficient predictive model for early prediction of the occurrence of HC. Methods: This study is a retrospective case-control study that included 308 patients with PPROM divided into a case group and a control group in a 1:1 ratio. The final pathological results of the placenta in the case group showed chorioamnionitis, while the control group was negative. This study collected relevant clinical and examination data of each research subject before delivery. Univariate and multivariate analysis were used to compare the data between the two groups, explore the risk factors for HC. And then a scoring formula was established based on the OR value to predict the occurrence of HC. Results: Univariate analysis showed statistical differences between the two groups in aspects age, gestational weeks(GW), time from the rupture to delivery(Duration), reproductive tract pathogens(RTP) cultivation, frequency of vaginal examinations(VE), antibiotic beginning time(ABT), glucocorticoids(GC) administering, Temperature(T), white blood cell(WBC) count and C-reactive protein(CRP). Multivariate analysis showed that VE, ABT, RTP, WBC and CRP were independent risk factors of HC. The AUC of ROC curve based on the established prediction formula reached 0.902, the sensitivity was 80.7%, the specificity was 86.2%, and the optimal cutoff value was 7.621. Conclusions: VE, ABT, RTP, WBC and CRP are independent risk factors for HC in PPROM patients. The prediction formula (0.60×VE+0.27×ABT+1.50+0.23×WBC+0.06×CRP) has good predictive value for the occurrence of HC. Individuals with a score above 7.621 have a significantly increased risk of developing HC.