The researchers also point out that the results may be even more "worrisome" than they appear at first glance. This is because when information was ambiguous, the researchers erred on the side of assigning higher appropriateness ratings.
On the basis of the findings, Chassin advised patients not to "accept uncritically" a physician's recommendations that they undergo risky procedures and to seek second opinions when doctors cannot relieve their doubts about the value of proposed treatments.
"There is a strong interest on the part of the public to believe in the scientific basis of medicine, even . . . (when) it isn't there," added Dr. John E. Wennberg of Dartmouth Medical School in Hanover, N.H., who wrote an editorial about the RAND study for the medical journal.
The RAND researchers said their data may "stimulate a productive educational dialogue" among physicians. It also may spur insurance companies, corporations and the federal Health Care Financing Administration, one of the study's sponsors, to crack down on unnecessary care through intensified reviews of elective medical and surgical procedures.
Chassin said he and his colleagues will analyze the data further to see if, for example, specialist physicians provide more or less inappropriate care than generalist physicians or if rich patients receive more unnecessary care than poor patients or vice versa. They are also preparing related studies to evaluate the quality of care in the Medicare program and the wide variations among hospitals in their death rates for elderly patients.
Dartmouth's Wennberg, an expert on geographic variations in medical care, said in an interview that the RAND studies should spur the development of "a National Institute of Health devoted to health care outcomes."
He added: "The problem is disagreement and uncertainty among physicians about the best way of practicing medicine. The reason is that the studies to find out what works have not been done, and when they have been done, they often have not been done well."
Chassin, however, took issue with Wennberg's pessimistic view of the state of physician knowledge.
"It is certainly true from the most rigorous scientific viewpoint that we know little about the efficacy of most modern medical treatments, but that is not to say physicians do not know how to make people better," he said. "The enormous amount of experience that has been gained over the years is also very important."
The RAND Corp. studied the appropriateness of common medical and surgical procedures. Here are the findings for three:
Cases Reviewed Appropriate Equivocal Inapprop. Coronary Angiography 1,677 74.0% 8.5% 17.4% Carotid Endarterectomy 1,302 35.3% 32.3% 32.4% Upper Gastrointestinal Tract Endoscopy 1,585 72.0% 10.8% 17.2%