A new review of drug trials revealed that studies funded by the pharmaceutical industry are more likely to produce favorable results than nonprofits and federal organizations.

Children's Hospital Boston researchers analyzed 546 drug trials conducted between 2000 and 2006, and found that industry-funded trials reported positive outcomes 85% of the time compared with 72% of the time for trials funded by nonprofits or non-federal organizations and 50% of the time for government-funded trials.

Among the nonprofit or non-federal studies, those that received industry contributions had positive outcomes 85% of the time compared with 61% of the time for those that did not have any industry support.

The drug trials reviewed were listed with ClinicalTrials.gov, a Web-based U.S. government registry of clinical trials, and included five types of drugs: cholesterol-lowering medicines, antidepressants, antipsychotics, proton-pump inhibitors, and vasodilators.

The study was published in the Aug. 3 issue of the journal Annals of Internal Medicine.

Researchers said the disparity could be because whoever funds a drug trial can manipulate the design of the study.

“There are a number of things that investigators designing trials can do that can then subsequently add up to factors that result in more favorable results,” said the study’s lead author Florence Bourgeois.

Bourgeois said drug companies can be selective in choosing questions, focus on certain aspects of a drug’s performance, cherry-pick patients, and decide the time period of a study.

Pharmaceutical industry can also be more selective in what studies it funds. Drug companies want to support trials that have a reasonably good chance of landing on the market for profit.

The study also found that only 32 percent of industry-funded trials published results within two years of clinical trial completion, compared with 54 percent of government-funded studies and 56 percent of nonprofit and nonfederal trials.

"While we cannot specifically point to which factors contribute to the association between funding source and positive result reporting, our findings speak to the need for more disclosure of all elements of a study," said Bourgeois.

"Publication bias is likely a contributing factor, but there may be many more, including biases in study design, patient selection, data analysis and results reporting," she added.

Biases in study can undermine the integrity of medical research yet researchers said preventing pharmaceutical firms from funding drug is an impractical solution because industry funds the lion’s share of most clinical trials.

More oversight and disclosure in drug trials are needed to ensure objective studies with unbiased results, Bourgeois said.