Background: The conclusiveness of a systematic review influences the strength of practice recommendations. A study in 2006 showed that two-thirds of Cochrane neonatal reviews were conclusive. Ten years later, with many new and updated reviews, it is unclear whether the finding has changed.
Objectives: We determined the proportion of Cochrane neonatal reviews that were conclusive, and assessed whether the size of the evidence gathered affected the conclusiveness of the review.
Methods: We analysed published Cochrane neonatal reviews up to issue 12, 2015, focusing on the main intervention-outcome combination. Two authors independently evaluated the abstract conclusions and selected one out of five possible options: clearly beneficial, clearly non-beneficial (conclusive), perhaps beneficial, perhaps non-beneficial and unclear either way (inconclusive).
We performed logistic regression to examine the association between the number of included studies and cumulative sample size and the likelihood of a review being conclusive (SPSS 22, Chicago, IL, USA).
Results: Overall, 319 reviews were assessed. Excluding 43 empty reviews, 103 reviews (37.3%) were conclusive (beneficial: 63 (22.8%), non-beneficial (40 (14.5%)) and 173 (62.7%) were inconclusive (perhaps beneficial: 80 (29.0%), perhaps non-beneficial: 5 (1.8%), unclear either way: 88 (31.9%)). Reviews with more studies were more likely to be conclusive (OR 1.07, 95% CI 1.03 to 1.12 for each added study, P 0.001), but no independent association was observed between cumulative sample size and conclusiveness of a review (P 0.30). Among reviews published pre-2000, 70% were conclusive, compared to 34.8% post-2000.
Conclusions: The majority of Cochrane neonatal reviews are inconclusive. The major decline in the proportion of conclusive reviews post-2000 was not clearly attributed to the size of evidence. Our findings suggest that in Neonatology, incremental benefits of newer interventions over older ones may no longer be clear-cut. Clinical decisions may increasingly depend on the clinical context, individual perception of benefit and harm, and values and preferences of those involved in the care of neonates.