Preventive medicine has taken on a new meaning -- to protect the doctor from malpractice suits. Paul Huth, a lawyer in Detroit, founded Physician's Alert in 1983 to help doctors avoid malpractice claims by identifying litigious patients in advance. The information will help doctors decide how -- and even whether -- to treat people who ask for their help.

Before starting the business, Huth found in his own survey that 35% of all the people who filed malpractice suits in Detroit during a three-month period had been plaintiffs in previous civil actions. When he started Physician's Alert, he sent workers to check the docket in the city courthouse manually; now, Docket Search Network Inc., in Chicago, which acquired Physician's Alert last fall, is completing a computerized file of every civil action in Detroit since 1948.

Ten years of Chicago records have already been computerized. To check a patient's litigation history, Chicago doctors call DSN's office, where a clerk performs a search and reads the results within 15 seconds. DSN charges doctors an annual membership fee of $150, plus an additional charge for each request.

Huth figures he can sign up at least 5% of the doctors in any city because of increasing concern about lawsuits. Patients are filing three times as many malpractice suits as they did a decade ago, according to the American Medical Association, and malpractice insurance can now cost a doctor more than $60,000 a year. In February, the AMA proposed sweeping actions to reduce the number of lawsuits and lower the average payout per claim.

Physician's Alert plans to expand to New York City, Los Angeles, and San Francisco this year, followed by six more cities next year. Huth is recruiting law firms to compile the litigation histories in return for royalties on the searches.

The new service could spell trouble for patients who filed lawsuits in the past for legitimate reasons. But Huth argues that doctors will treat these patients more conservatively, rather than turn them away at the door. "Medicine is too competitive today to just give patients away," he says.

On the other hand, patients might like to buy a printout of their own -- detailing the doctor's litigation history.