TUESDAY, Oct. 23, 2007 (HealthDay News) -- Drug company-funded studies of asthma drugs called inhaled corticosteroids are less likely to find adverse effects than studies that were paid for by other sources, Spanish researchers say.
A team from Children's Hospital La Fe in Valencia analyzed 504 studies of the drugs conducted between 1993 and 2002.
Potentially harmful decreases in the stress hormone cortisol, decreases in bone mineral density, and growth suppression are among the adverse effects that have been associated with inhaled corticosteroids, the researchers note.
Of the 504 studies, 275 were funded by drug companies and 229 were funded by other sources, such as government agencies and non-profit organizations.
The researchers found that 34.5 percent of drug company-funded studies and 65.1 percent of studies funded by other sources identified significant differences in adverse events between patients who took inhaled corticosteroids and those in control groups who didn't take the drugs.
The researchers said the difference was no longer statistically significant when they factored in components of study design, such as dosage amounts or a focus limited to specific adverse effects. This suggests that the association between funding source and more positive findings may be the result of variations in how the studies were designed, said the researchers.
They noted that it's difficult to determine if drug company-funded studies are too positive or whether studies funded by other sources are too cautious.
Still, "having information on source of funding will help readers of these studies have a better informed and balanced judgment on the authors' interpretations," they concluded. "Disclosure of conflicts of interest should be strengthened for a more balanced opinion of the safety of drugs."
The study appears in the Oct. 22 issue of the journal Archives of Internal Medicine.
The American Lung Association has more about asthma medications.