Chorioamnionitis as a risk factor for bronchopulmonary dysplasia: a systematic review and meta-analysis

Objective To conduct a systematic review of the association between chorioamnionitis (CA) and bronchopulmonary dysplasia (BPD) in preterm infants. Methods The authors searched Medline, Embase, CINAHL, Science Citation Index and PubMed, reviewed reference lists and contacted the primary authors of relevant studies. Studies were included if they had a comparison group, examined preterm or low birthweight infants, and provided primary data. Two reviewers independently screened the search results, applied inclusion criteria and assessed methodological quality. One reviewer extracted data and a second reviewer checked data extraction. Studies were combined with an OR using a random effects model. Meta-regression was used to explore potential confounders. Results 3587 studies were identified; 59 studies (15 295 patients) were included. The pooled unadjusted OR showed that CA was significantly associated with BPD (OR 1.89, 95% CI 1.56 to 2.3). Heterogeneity was substantial (I-2=66.2%) and may be partially explained by the type of CA. Infants exposed to CA were significantly younger and lighter at birth. The pooled adjusted OR was 1.58 (95% CI 1.11 to 2.24); heterogeneity was substantial (I-2=65.1%) which may be due to different variables being controlled in each study. There was strong evidence of publication bias which suggests potential overestimation of the measure of association between CA and BPD. Conclusions Unadjusted and adjusted analyses showed that CA was significantly associated with BPD; however, the adjusted results were more conservative in the magnitude of association. The authors found strong evidence of publication bias. Despite a large body of evidence, CA cannot be definitively considered a risk factor for BPD.