Cervical interleukin-6 as a predictive test for preterm delivery in symptomatic women: preliminary results.

OBJECTIVE The aim of this study is to assess the efficacy of cervical interleukin-6 (IL-6) compared with cervical length and its association in the prediction of preterm delivery in symptomatic women. STUDY DESIGN Observational prospective study was performed at Hospital Universitario La Fe, Valencia (Spain). SAMPLE 100 women between 24 and 34 weeks gestational age, with threatened preterm delivery and intact membranes during the period 2006-2008. METHODS Transvaginal scan to assess cervical length was performed and cervical swab for IL-6 detection was taken. Statistical analysis included Chi-square test, receiver operating characteristic (ROC) curve analysis, COX regression, logistic regression, and Kaplan-Meier survival analysis. RESULTS The prevalence of preterm delivery at <37 weeks was 35% and at <32 weeks was 5%. Cervical length was <15 mm in 12% and <30 mm in 62% of the cases. Cervical length and IL-6 were useful for prediction of delivery at 48 h, 7 days, <32, and <34 weeks. Using ROC curves, the IL-6 value that showed best accuracy for prediction of preterm delivery was >210 pg/ml. No differences were observed between the area under the curve (AUC) of IL-6 and cervical length for the prediction of preterm delivery. The association of IL-6 (>210 pg/ml) and cervical length (<30 mm) increases the prediction of either alone. CONCLUSIONS Cervical IL-6 can predict preterm delivery similarly to cervical length; when combined, it adds prognostic information to that provided by sonographic measurement of the cervical length.