Variation in the tendency of primary care physicians to intervene

Research has documented dramatic variation in health care spending across the United States that has little relationship to health outcomes. Although high-spending areas have more physicians per capita, it is not known whether this disparity fully explains the differences in spending or whether individual physicians in high-spending regions have a greater tendency to intervene for their patients. We sought to measure the tendency of primary care physicians to intervene across regions that differ in their levels of local health care spending.

We used data from the Community Tracking Study Physician Survey, a telephone survey of a nationally representative sample of 5490 primary care physicians who provided care to adults in 1998-1999 (response rate 59%). Local health care spending in physicians' communities was determined by assigning each participating physician to 1 of 306 US hospital referral regions. The tendency of physicians to intervene was measured by evaluating their responses to 6 clinical vignettes in which they were asked how often they would order a test, referral, or treatment for the patient described.

In 5 of the 6 vignettes, physicians in high-spending regions were more likely to recommend interventions than those practicing in low-spending regions. For example, for a 35-year-old man with back pain and foot drop, physicians in high-spending regions would recommend magnetic resonance imaging 82% of the time, compared with 69% for physicians in low-spending regions (P<.001). For a 60-year-old man somewhat bothered by symptoms of benign prostatic hypertrophy, physicians in high-spending regions would make a urology referral 32% of the time, while those in low-spending regions would do so only 23% of the time (P<.001). Our findings that physicians in high-spending regions have a greater tendency to intervene persisted in analyses stratified by physician specialty (family/general practice vs internal medicine).

Varying rates of health care spending across the United States reflect the underlying tendency of local physicians to recommend interventions for their patients.