Growth of single-specialty medical groups.

Using site-visit data from the Community Tracking Study, we show that specialists are increasingly forming large single-specialty medical groups, particularly in orthopedics and cardiology, where new technologies have increased the number of diagnostic imaging and surgical services that can be provided in outpatient settings. Specialists are also forming large groups to gain negotiating leverage with health plans; the decline of managed care and the fading of the perception of a specialist surplus has made single- rather than multispecialty groups an attractive means to gain leverage. We explore possible consequences of this shift in physician practice organization and its policy implications.