SLIDE 1
Abstract Session E1: Organization of Care and Chronic Disease Management
Moderator: Nancy A. Rigotti, MD
UNDERSTANDING VARIATION IN PCP REFERRAL PATTERNS IN A LARGE MULTISPECIALTY PRACTICE GROUP Michael L. Barnett1; Thomas D. Sequist1,2. 1Brigham and Women's Hospital, Boston, MA; 2Partners Healthcare System, Boston, MA. (Tracking ID #1937624) BACKGROUND: Primary care physicians (PCPs) generate the vast majority of specialty referrals, and the decision to refer directly impacts health care quality, patient experiences, and spending. We analyzed referral rates among PCPs to characterize the relative contribution of patient and physician characteristics to the probability of referral, as well as the long term impact on utilization among PCPs with high rates of referral. METHODS: We analyzed electronic health record data within a large multispecialty group practice that requires electronic referral
- rders. We enrolled 78,485 patients 18 years and older who visited 142 PCPs during a baseline referral rate measurement period
(2005-2006), and then analyzed subsequent specialist referrals among these patients from 2007-2011. We collected information on patient age, gender, race, Charlson comorbidity score (2005-2006), and number of subsequent specialist appointments (2007-2011). To calculate PCP referral rates, we estimated a mixed effects logistic regression model using 2005-2006 data adjusted for patient characteristics, using a random intercept term to account for correlation within individual PCPs. We calculated the ratio of the PCP's adjusted referral rate estimated from the fitted random intercept over the expected referral rate estimated with the same model without the random intercept. We multiplied this ratio by the average referral rate in the entire cohort to calculate the case-mix adjusted referral rate for each PCP. We used the c-statistic to assess the relative contribution of patient and physician characteristics in this
- model. We next categorized PCPs according to their quintile of adjusted referral rate and examined the characteristics of the PCPs and
their patient panels, testing for trends using logistic regression. In the period from 2007-2011, we estimated the adjusted probability with logistic and negative binomial models that patients with PCPs in the different referral quintiles received any specialty referral, the average number of referrals per patient, and the average number of specialty visits. RESULTS: From 2007-2011, the PCPs placed 102,276 referral orders, representing 74% of the total referrals for this cohort (additional referrals came from urgent care physicians). The five most commonly referred specialties were orthopedic surgery (23%), dermatology (15%), otorhinolaryngology (9%), gastroenterology (9%), and general surgery (8%). Physicians with more female, non- white and younger patients as well as those with fewer comorbidities were more likely to be in the highest referral quintile, as were physicians with fewer patient encounters and smaller panels (all p<0.001, Table). The c-statistic for a logistic regression model to predict referrals using patient characteristics alone was 0.56, while the mixed effects model with a physician-level random intercept alone had a c-statistic of 0.68, which was unchanged after incorporating patient characteristics into the model. The adjusted average rate of referral per 100 patient visits was 5.2, 16.3, 21.0, 25.6, and 36.2 by quintile of referral rate among PCPs, with an overall average of 17.4. Adjusting for age, sex, race, and comorbidities, the average patient with a PCP in the highest quintile of referral rate had a 77% (95% CI 76-78) probability of receiving a referral and had 2.2 (95% CI 2.1-2.3) referrals on average from 2007-2011, compared to a 36% (95% CI 35-37) chance of receiving a referral and 0.59 (95% CI 0.57-0.61) average number of referrals in lowest
- quintile. From 2007-2011, in the 12 months subsequent to a referral, patients of PCPs in the highest referral quartile experienced an