Prevalence of health problems and primary care physicians' specialty referral decisions.

OBJECTIVE The researchers tested the hypothesis that the frequency with which patients present to primary care physicians with certain types of health problems is inversely related to the chances of specialty referral during an office visit. STUDY DESIGN Cross-sectional analysis. POPULATION The researchers used a data set composed of 78,107 primary care visits from the 1989 to 1994 National Ambulatory Medical Care Surveys. The physicians completed questionnaires after office visits. OUTCOMES MEASURED The frequency of a health problem's presentation to primary care (practice prevalence) was defined as the percentage of all visits made to family physicians, general internists, and general pediatricians for that particular problem. The researchers estimated the correlation between a condition's practice prevalence and its referral ratio (percentage of visits referred to a specialist) and used logistic regression to estimate the effect of practice prevalence on the chances of referral during a visit. RESULTS The practice prevalence of a condition and its referral rate had a strong inverse linear relationship (r=-0.87; P<.001). Compared with visits made for the uncommon problems, the odds of referral for those with intermediate or high practice prevalence were 0.49 (P=.004) and 0.22 (P<.001), respectively. Surgical conditions were referred more often than medical conditions, and a greater burden of comorbidities increased the odds of referral. CONCLUSIONS Primary care physicians are more likely to make specialty referrals for patients with uncommon problems than those with common conditions This finding highlights the responsible judgment primary care physicians employ in recognizing the boundaries of their scope of practice. Practice prevalence is a defining feature of the primary care-specialty care interface.