(HealthDay News) — Source of funding for spinal research is significantly associated with study outcome and level of evidence (LOE), according to a review published in the February 1 issue of The Spine Journal.

Amir Reza Amiri, from the Royal National Orthopaedic Hospital in Stanmore, U.K., and colleagues conducted a systematic literature review of 1,356 published spinal studies in five leading spinal, orthopedics, neurosurgery, and general medical journals (online or print) during 2010. Information on self-reported potential conflict of interest and type of funding (foundation, industry, public, intramural, multiple [including industry], multiple [without industry], and unfunded) were identified for each paper. Oxford Center for Evidence-Based Medicine guidelines were used for LOE ranking.

The researchers observed a significant association between LOE and source of funding (P<0.01). The greatest proportion of level IV evidence was industry-funded studies (65%). The proportion of industry-funded studies with favorable outcomes was significantly higher than that of publicly- and foundation-funded studies (88% vs. 73 and 74%, respectively). In industry-funded studies, the associated odds ratio for reporting favorable outcomes was 2.7 compared to studies with public funding and 2.6 compared to studies with foundation funding. The highest proportions of unfavorable (14%) and equivocal (23%) outcomes were seen with level I studies, whereas level IV studies had the highest proportion of favorable outcome (85%). Self-reported conflict of interest was not associated with LOE (P=0.83) or study outcome (P=0.25).

“We demonstrated a significant association between source of funding, study outcome, and LOE in spinal research,” the authors write.

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