Objective: From the literature search for a government-commissioned systematic review on surgical treatments for benign prostatic enlargement (BPE), we identified the relevant conference abstracts of randomised controlled trials (RCTs) which failed to reach full publication and their data were not utilised. We aimed to ascertain, first, the reasons of failure to reach full publication and second, to estimate the impact of including the abstracts' data.
Design: A two-part study, consisting of a questionnaire survey and a sensitivity analysis of the above said review.
Methods: An ad hoc questionnaire was sent to each author of the relevant abstracts, as to determine the reasons of failure to reach full publication. The data from the abstracts were then extracted and incorporated into sensitivity analysis of the review.
Results: Forty-seven questionnaires were completed for 47 abstracts. Of these abstracts, 32 of them were claimed to have reached full publication. A number of reasons of failure to reach full publication were identified, for example: 'being written up' and 'lack of time'. Utilizable, relevant data were obtained from eight of the 47 abstracts, and put into sensitivity analysis. There were small changes in effect sizes and directions for three of 14 reviews' secondary outcomes.
Conclusion: Common reasons of failure to reach full publication were also identified in the context for the BPE review. Inclusion of abstract data did not affect primary outcome defined in the original review. Identification, summarisation of conference abstracts and other grey literature should form an essential exercise for any systematic review.