Original article
Discrepancy between Results and Abstract Conclusions in Industry- vs Nonindustry-funded Studies Comparing Topical Prostaglandins

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Purpose

To investigate the relationship between industry- vs nonindustry-funded publications comparing the efficacy of topical prostaglandin analogs by evaluating the correspondence between the statistical significance of the publication's main outcome measure and its abstract conclusions.

Design

Retrospective, observational cohort study.

Methods

English publications comparing the ocular hypotensive efficacy between any or all of latanoprost, travoprost, and bimatoprost were searched from the MEDLINE database. Each article was reviewed by three independent observers and was evaluated for source of funding, study quality, statistically significant main outcome measure, correspondence between results of main outcome measure and abstract conclusion, number of intraocular pressure outcomes compared, and journal impact factor. Funding was determined by published disclosure or, in cases of no documented disclosure, the corresponding author was contacted directly to confirm industry funding. Discrepancies were resolved by consensus. The main outcome measure was correspondence between abstract conclusion and reported statistical significance of the publications' main outcome measure.

Results

Thirty-nine publications were included, of which 29 were industry funded and 10 were nonindustry funded. The published abstract conclusion was not consistent with the results of the main outcome measure in 18 (62%) of 29 of the industry-funded studies compared with zero (0%) of 10 of the nonindustry-funded studies (P = .0006). Twenty-six (90%) of the industry-funded studies had proindustry abstract conclusions.

Conclusions

Twenty-four percent of the industry-funded publications had a statistically significant main outcome measure; however, 90% of the industry-funded studies had proindustry abstract conclusions. Both readers and reviewers should scrutinize publications carefully to ensure that data support the authors' conclusions.

Section snippets

Methods

A MEDLINE search from 1966 to the second week of November 2007 using any combination of the keywords latanoprost, travoprost, and bimatoprost was conducted. The title and abstracts from the initial search were reviewed and those included were English language publications comparing the intraocular pressure (IOP)-lowering efficacy of any combination of latanoprost; travoprost; or bimatoprost. The complete articles were obtained and the references also were searched to identify relevant

Results

A total of 180 articles were identified by the original search. After reviewing the abstracts, 39 met the inclusion criteria and were included in the study. In reviewing the references of these publications, no additional publications were found. Of the 39 publications, 35 were studies that directly compared two or three of the PGAs and four were meta-analyses. Thirty-five of the publications included a disclosure statement, and four had no documented disclosure. The authors were contacted

Discussion

We found that 62% of the industry-funded vs none of the nonindustry-funded studies' abstract conclusions did not correspond with the results of the main outcome measure (P = .0006, Fisher exact test). Although only 24% of the industry-funded publications had a statistically significant main outcome measure, 90% of the industry funded studies had a proindustry abstract conclusion.

The influence of industry on publications involving a wide range of diseases and drugs is well documented.2, 5, 6, 7,

Dr Yvonne Buys completed her MD, ophthalmology residency, and glaucoma fellowship at the University of Toronto, Toronto, Canada. She is currently an Associate Professor at the University of Toronto, Department of Ophthalmology, Co-Director of the Glaucoma Unit at the University Health Network, and President of the Canadian Glaucoma Society. Dr Buys is involved in training ophthalmology residents and glaucoma fellows. She has published over 60 peer-reviewed papers and three book chapters in the

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  • Cited by (0)

    Dr Yvonne Buys completed her MD, ophthalmology residency, and glaucoma fellowship at the University of Toronto, Toronto, Canada. She is currently an Associate Professor at the University of Toronto, Department of Ophthalmology, Co-Director of the Glaucoma Unit at the University Health Network, and President of the Canadian Glaucoma Society. Dr Buys is involved in training ophthalmology residents and glaucoma fellows. She has published over 60 peer-reviewed papers and three book chapters in the area of glaucoma.

    Dr Tariq Alasbali completed his MD, ophthalmology residency at King Faisal University and a glaucoma fellowship at King Khaled Eye Specialist Hospital (KKESH) in Saudi Arabia. Dr Alasbali completed a research fellowship and currently he is a clinical glaucoma fellow at the University of Toronto, Department of Ophthalmology. Dr Alasbali received a Canadian Ophthalmological Society award for excellence in ophthalmic research in 2007.

    See accompanying Editorial on page 1.

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