The laws aim to shed light on drug companies' influence over doctors' decisions on which drugs to prescribe. But weaknesses in laws in the two states studied — Vermont and Minnesota — make it difficult to know how much money is changing hands and who is receiving it, according to the report.
Most payments studied were related to education, research, meals, and personal visits with doctors to promote new drugs, the researchers said. But reasons for many payments were not specified, sometimes because companies declared them trade secrets.
The issue is important to consumers because doctors may end up recommending drugs because of industry influence, not patients' best interests, said lead author Dr. Joseph Ross, a researcher at Mount Sinai School of Medicine in New York.
But the information was not easily accessible, requiring lawsuits in Vermont and photocopying individual disclosure forms in Minnesota, the researchers said.
"The hoops that we had to jump through just to get the data in each state is enough to show these laws really aren't working," Ross said.
The results highlight the need for better enforcement of existing laws, and should help others craft better ones elsewhere, the authors said.
Minnesota and Vermont were the first to enact disclosure laws, in 1993 and 2001 respectively. Defenders say it is not surprising to find imperfections in the pioneering efforts and that improvements are under way.
Disclosure laws also exist in California, the District of Columbia, Maine and West Virginia; and similar legislation was proposed last year in 11 other states, the researchers said.
Their report appears in Wednesday's Journal of the American Medical Association.
Ross said it is unclear whether similar problems would be found elsewhere.
The pharmaceutical industry's efforts to influence doctors are pervasive. An article in JAMA last year said about 90 percent of the industry's roughly $21 billion annual marketing budget is spent on doctors.
AMA guidelines recommend that gifts to doctors should not exceed $100 and should benefit patients. Other medical groups and the Pharmaceutical Research and Manufacturers of America, or PhRMA, an industry trade group, have similar recommendations.
PhRMA attorney Marjorie Powell said many payments cited would be considered appropriate under the group's guidelines, including money for research and medical education. She also defended companies' rights to declare some payments trade secrets to keep competitors from learning about drugs under development.
A JAMA editorial said the study results suggest lawmakers may be ambivalent about imposing strict limits on industry gifts to doctors and that the report "undermines faith in industry self-regulation."
The researchers examined disclosures in Vermont from July 2002 through June 2004, and in Minnesota from January 2002 through December 2004.