Sponsorship bias and quality of randomised controlled trials in veterinary medicine

Abstract

BackgroundRandomised controlled trials (RCTs) are considered the gold standard form of evidence for assessing treatment efficacy, but many factors can influence their reliability including methodological quality, reporting quality and funding source.The aim of this study was to examine the relationship between funding source and positive outcome reporting in veterinary RCTs published in 2011 and to assess the risk of bias in the RCTs identified.MethodsA structured search of PubMed was used to identify feline, canine, equine, bovine and ovine clinical trials examining the efficacy of pharmaceutical interventions published in 2011. Funding source and outcomes were extracted from each RCT and an assessment of risk of bias made using the Cochrane risk of bias tool.ResultsLiterature searches returned 972 papers, with 86 papers (comprising 126 individual RCTs) included in the analysis. There was found to be a significantly higher proportion of positive outcomes reported in the pharmaceutical funding group (P) compared to the non-pharmaceutical (NP) and ‘no funding source stated’ (NF) groups (P = 56.9%, NP = 34.9%, NF = 29.1%, p < 0.05). A high proportion of trials had an unclear risk of bias across the five criteria examined.ConclusionsWe found evidence that veterinary RCTs were more likely to report positive outcomes if they have pharmaceutical industry funding or involvement. Consistently poor reporting of trials, including non-identification of funding source, was found which hinders the use of the available evidence.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-017-1146-9) contains supplementary material, which is available to authorized users.

Sample size and number of outcome measures of veterinary randomised controlled trials of pharmaceutical interventions funded by different sources, a cross-sectional study

“…The sample population was feline, canine, equine, bovine and ovine RCTs published in 2011 within journals indexed in PubMed. This study was conducted in parallel with Wareham et al [ 8 ] and the search strategy and literature filtering processes reported in full in that manuscript also apply to this study The same sample of literature was used for data extraction in both studies [ 8 ].…”

“…In a recent study, we reported that the source of funding (pharmaceutical company or other) has an effect on positive outcome reporting (sponsorship bias) in veterinary clinical trials [ 8 ]. The impact of funding on the size of trials and whether a sample size calculation has been undertaken remains unclear in medical RCTs [ 9 – 11 ].…”

“…To date, there has been no report of the influence of funding source on the size of veterinary RCTs and whether primary outcomes are stated or a sample size calculation has been undertaken. This study was done concurrently with Wareham et al [ 8 ] to examine further whether funding source has an effect on other aspects of trial design and delivery.…”

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“…Studies associated with a financial tie are 3.23-4.05 times more likely to report a positive significant effect of the sponsor's product (Ahn et al, 2017;Lexchin et al, 2003). Whilst understudied in the veterinary profession, a similar effect has been observed with commercially funded studies significantly more associated with a positive outcome (Wareham et al, 2017). The peer review process, whilst recognised as imperfect (e.g.…”

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