Paying doctors to reach clinical targets, a hot trend in the push to improve health care quality, may not lead to hoped-for improvements in care, researchers said on Tuesday.

A two-year study, published in the Journal of the American Medical Association, found that paying doctors bonuses for hitting certain quality goals mainly rewards doctors who already are top performers, while showing some increase in the number of patients screened for disease.

Health insurers increasingly are turning to such “pay-for-performance” programs - which give doctors incentives to reach certain clinical goals - despite the fact that little published research exists to support the trend.

In one of the first studies of the plans, researchers evaluated a pay-for-performance program conducted by insurer PacifiCare Health Systems Inc.

The study compared use of pay-for-performance for multi-specialty physician practices in California with practices in the Pacific Northwest that didn’t use pay-for-performance over more than two years.

It found that Cervical cancer screenings grew 5.3 percent for the California practices, compared to 1.7 percent among the doctors in the Pacific Northwest.

Mammography screenings rose 1.9 percent in California against a 0.2 percent climb in the Northwest, but the difference in favor of the pay-for-performance group was not statistically significant. Blood tests for diabetics rose about the same for each group.

The study also found that doctors already at the target levels received 75 percent of the bonus money.

“Pay-for-performance is a work in progress,” Meredith Rosenthal, the study’s lead author and an assistant professor at the Harvard School of Public Health, said in an interview.

Rosenthal said future pay-for-performance designs should incorporate incentives for doctors to improve, rather than just reach target goals.

“We’re really just starting to learn about what works here,” Rosenthal said.

An accompanying editorial in JAMA called for more research into the trend. Health plans, employer groups and governments sponsor nearly 100 pay-for-performance plans, the editorial said, despite limited research.

The study was funded by The Commonwealth Fund, a private foundation supporting independent health research.

SOURCE: Journal of the American Medical Association, October 12, 2005.