This is a guest post by Jennifer Horsley, PLOS Collections, Meghan Byrne, PLOS ONE and Sarah Wade, PLOS ONE. PLOS is a co-founding organisation of AllTrials.

The publication of negative results is vitally important for many reasons, not least that it helps prevent duplication of research effort and potentially expedites the process of finding positive results. The struggle to find a home to publish the work, however, and the effort necessary to submit and publish what can feel like negligible scientific contributions, has led to concerns that negative findings are becoming the missing pieces in the scientific literature.

Last month, the open access journal PLOS ONE launched a collection highlighting a selection of such results and discussed the benefits of these findings for the scientific community.

One particular field where failed work is often filed away and forgotten is medical research, with one recent study estimating that 29% of registered clinical trials go unpublished. The PLOS Collection showcases several trials that yielded no significant effects from treatment, the results of which may not have been widely shared unless there was a place to publish null results.

In one clinical trial, the authors found that a capsaicin patch was no more effective than placebo in reducing severe, persistent pain following surgery for inguinal hernias (hernias in the groin). The capsaicin patch would seem a logical treatment option because it is an established treatment for chronic pain associated with injured nerve fibres. Sharing the null results of this study may prevent other researchers from putting effort into similar clinical trials and allow them to focus future research on alternative treatment strategies.

In a secondary analysis of another clinical trial, the authors found that participating in women’s health groups did not reduce women’s postpartum psychological distress compared with usual perinatal care in rural Bangladesh. The authors hypothesized that the women’s health groups, whose aim was to improve women’s and children’s health, would have a significant effect, based on similar studies in eastern rural India. These null results suggest that researchers may need to look at other factors in the women’s lives, specific to Bangladesh, to address mental health issues following childbirth.

By highlighting these results, this new collection aims to demonstrate the value of negative and inconclusive findings as the key missing pieces of the scientific literature.

Please visit the collection at: