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

OBJECTIVE We tested the hypothesis that the frequency with which patients p resent to primary care physicians with certain types of health problems is inversely related to the chances of specialty referral during an office vis it. STUDY DESIGN Cross-sectional analysis. POPULATION We used a data set composed of 78,107 primary care visits from t he 1989 to 1994 National Ambulatory Medical Care Surveys. The physicians co mpleted questionnaires after office visits. OUTCOMES MEASURED We defined the frequency of a health problem's presentati on to primary care (practice prevalence) as the percentage of all visits ma de to family physicians, general internists, and general pediatricians for that particular problem. We 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 pra ctice 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 visit s made for the uncommon problems, the odds of referral for those with inter mediate or high practice prevalence were 0.49 (P=.004) and 0.22 (P < .001), respectively. Surgical conditions were referred more often than medical co nditions, and a greater burden of comorbidities increased the odds of refer ral. CONCLUSIONS Primary care physicians are more likely to make specialty refer rals for patients with uncommon problems than those with common conditions. This finding highlights the responsible judgment primary care physicians e mploy in recognizing the boundaries of their scope of practice. Practice pr evalence is a defining feature of the primary care-specialty care interface .