The researchers said that the "claim-prone" physicians were disproportionately male (82 percent) and were older, rather than younger. More than half the claims were by doctors in one of four areas: internal medicine, obstetrics and gynecology, general surgery and general practice or family medicine.
But the biggest predictor of all in the claim-prone doctors was whether they'd had a prior claim.
"Compared to physicians with only one previous claim," Studdert said, "a physician who has had three previous claims is three times as likely to have another one. A physician who has had four is four times more likely and so on."
In the study the researchers are clear that they have identified risk factors but that it is up to health care systems, hospital and malpractice insurers to identify and work with these doctors. But they noted that few of these organizations do.
"With notable exception," the researchers write, "fewer still systematically identify and intervene with practitioners who are at high risk for future claims." They call for further investigation into predicting which doctors are at risk and then implementing interventions such as training and supervision to improve their quality of care.
In California, patients can look up their doctor on the state's medical board website. Depending on the type of malpractice settlement, it will be part of the public record if the doctor has had either three or four settlements within a five-year period. Other information is also available, including whether your doctor has had a felony conviction or is on probation. Patients can use the website simply to determine that a doctor's license is valid.
But advocates like Lisa McGiffert, with Consumers Union's Safe Patient Project, say that's not enough and have been pushing the Medical Board of California to require that doctors placed on probation notify their patients. The board has resisted taking this step.
While probation and multiple malpractice claims are not necessarily linked, McGiffert says she hopes doctors will pay attention to this study. "Because I have this sense that doctors as a group protect other doctors who are on probation or get in trouble because they think it might happen to them," she said, but since this study demonstrates that a small percentage of doctors are responsible for a disproportionate number of claims, it should be reassuring to physicians.