The effect of journal impact factor, reporting conflicts, and reporting funding sources, on standardized effect sizes in back pain trials: a systematic review and meta-regression

Robert Froud, Tom Bjorkli, Philip Bright, Devan Rajendran, Rachelle Buchbinder, Martin R Underwood, David Evans, Sandra Eldridge

Research output: Contribution to journalArticleResearchpeer-review

6 Citations (Scopus)


Background: Low back pain is a common and costly health complaint for which there are several moderately effective treatments. In some fields there is evidence that funder and financial conflicts are associated with trial outcomes. It is not clear whether effect sizes in back pain trials relate to journal impact factor, reporting conflicts of interest, or reporting funding. Methods: We performed a systematic review of English-language papers reporting randomised controlled trials of treatments for non-specific low back pain, published between 2006-2012. We modelled the relationship using 5-year journal impact factor, and categories of reported of conflicts of interest, and categories of reported funding (reported none and reported some, compared to not reporting these) using meta-regression, adjusting for sample size, and publication year. We also considered whether impact factor could be predicted by the direction of outcome, or trial sample size. Results: We could abstract data to calculate effect size in 99 of 146 trials that met our inclusion criteria. Effect size is not associated with impact factor, reporting of funding source, or reporting of conflicts of interest. However, explicitly reporting no trial funding is strongly associated with larger absolute values of effect size (adjusted ?=1.02 (95 CI 0.44 to 1.59), P=0.001). Impact factor increases by 0.008 (0.004 to 0.012) per unit increase in trial sample size (P
Original languageEnglish
Pages (from-to)1 - 18
Number of pages18
JournalBMC Musculoskeletal Disorders
Issue number1 (Art. No: 370)
Publication statusPublished - 2015

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