Publication bias may exist among prognostic accuracy studies of middle cerebral artery Doppler ultrasound

Objectives: The objective of this study was to assess if there is evidence of publication bias in prognostic accuracy studies of middle cerebral artery (MCA) or cerebroplacental ratio (CPR) for adverse perinatal outcome. Study Design and Setting: We queried PubMed, EMBASE, the Cochrane Library, and ClinicalTrials.gov and searched abstract books of five perinatal conferences (1989–2017). We included prognostic accuracy studies on MCA and/or CPR. Highest reported accuracy estimates, sample size, study design, and conclusion positivity were extracted and compared. Results: We included 127 full-text articles and 51 conference abstracts, 29 of which had not been reported as full-text article. In conference abstracts not reported in full, median negative predictive value was significantly lower compared to full-text articles (0.79 [interquartile range 0.67–0.97] vs. 0.95 [0.89–0.99]; P < 0.001). No significant difference was identified for positive predictive value (0.62 vs. 0.59; P = 0.827), sensitivity (0.67 vs. 0.71; P = 0.159), and specificity (0.86 vs. 0.86; P = 0.632). Study design differed significantly as well (P = 0.030), with fewer prospective studies in conference abstracts not reported in full compared to full-text articles (28% vs. 54%). We found no significant differences in sample size or conclusion positivity. Conclusion: Possibly, a publication bias in previously published meta-analyses of MCA and CPR has led to overly generous estimates of prognostic performance.