Industry funding doesn't appear to boost the likelihood of positive outcomes among published studies of drugs for rheumatoid arthritis (RA), researchers found.

About 75 percent of published studies funded by industry showed a positive result, compared with nearly 70 percent of those not funded by industry, which wasn't a significant difference, Nasim Khan, MD, of the University of Arkansas in Little Rock, and colleagues reported in Arthritis & Rheumatism.

But when looking at all trials listed on ClinicalTrials.gov, they noted that trials sponsored by drug companies were more likely not to be published, though the trend wasn't significant.

"Although a preponderance of the data in the medical literature shows that industry funding leads to higher chances of pro-industry results and conclusions, we did not observe any association between the funding source and the study outcome of 'published' [trials] of RA drug therapies," they wrote.

The authors did caution that publication bias could be at work, as trials with unfavorable results may be less likely to be published.

Khan and colleagues assessed 103 randomized controlled trials, 58 of which were funded by industry, 19 by nonprofits, and six with mixed funding. The rest of the reports didn't have funding information available.

Among the trials for which outcomes could be assessed, 75.5 percent of industry-funded trials had a positive outcome compared with 68.8 percent of trials funded by nonprofits.

"We could not ascertain whether 'published' [trials] more commonly presented outcomes that were favorable but different from the originally planned primary outcomes, thus inflating the frequency of positive 'published' trials," they noted.

They said further study is needed to address the "extent and implications" of publication bias in RA drug trials.

In general, the researchers found that studies funded by industry involved significantly more study centers and patients, and were stronger in their methodology. For instance, these trials were more likely to be double-blind, had better descriptions of participant flow, and performed more intent-to-treat analyses.

Studies funded by nonprofits, on the other hand, lasted longer and were more likely to examine different treatment strategies.

These differences "clearly highlight the importance of both industry and nonprofit sources for funding of randomized, controlled trials to generate efficacy and safety evidence for newer as well as established drugs and strategies for their use in clinical care," they wrote.

The study was limited because about a fifth of the published trials had no funding source disclosed. Also, there was the potential for investigators to not report certain aspects of methodology, and the researchers didn't evaluate the specific conclusions or recommendations offered by trial investigators.

Source: Rheumatoid Arthritis Trial Results Not Skewed by Industry Dollars