Outside financial interests in radiology offices: prevalence, payment, and practice patterns in involved offices

The purposes of our study were to (1) investigate the prevalence of different patterns of outside financial interests in radiology offices and of different methods of compensating these interests and (2) determine how the professional, operational, and practice characteristics of the offices vary with the patterns of outside interest. The term "office" means nonhospital practice sites, including those called imaging centers or clinics; "outside interests" refers to parties other than physicians in the group of physicians who serve the office.

Data are for 516 office sites served by radiology groups. Data were collected as part of a national, stratified random sample survey of radiology groups in the United States done by the American College of Radiology in 1992. Responses were weighted to make the results representative of all radiology groups in the United States with offices.

Parties other than the physicians in the practice serving an office had a financial interest in 41% of offices. In about half of these (20% of all offices), physicians in the practice had no financial interest at all. The most common categories of outside financial interest were referring physicians (21%), hospitals (19%), and non-physician entrepreneurs (12%); some offices reported more than one type of outside financial interest. All categories were more common in high-tech offices (offices that offered CT, MR imaging, or nuclear medicine studies) than in non-high-tech offices. Overall, 50% of high-tech offices and 35% of non-high-tech offices had outside financial interests. The most common method of compensating outsiders was giving them shares or dividends or a percentage of the profits. The average number of procedures per full-time-equivalent radiologist was higher in offices in which only outsiders (and not the group serving the office) had a financial interest than in other offices, and fewer of the former offices offered mammography. Offices with no outside interests were more likely than those with any outsiders to regularly do chest, spinal, gastrointestinal, and urologic procedures.

Outside financial interests, and the problems of cost and access they may engender, are fairly common in radiology offices. Nationally, joint ventures including referring physicians, which are now under legal attack, number more than 500. Differences in who owns radiology offices were associated with statistically significant variations among offices in workload, staffing, and types of procedures done.