Patterns of referral in a Canadian primary care electronic health record database: retrospective cross-sectional analysis

Joshua Shadd, Bridget Ryan, Heather Maddocks, Amardeep Thind


Background Databases derived from primary care electronic health records (EHRs) are ideally suited to study clinical influences on referral patterns. This is the first study outside the United Kingdom to use an EHR database to describe rates of referral per patient from family physicians to specialists.
Objective To use a primary care EHR database to describe referrals to specialist physicians; to partition variance in referral rates between the practice and patient levels.
Methods Retrospective cross-sectional analysis of de-identified EHRs of 33 998 patients from 10 primary care practices in Ontario, Canada. The study cohort included all patients who visited their family physician 1 April 2007 to 31 March 2008 (n_24 856). Specialist referrals for each patient were counted for 12 months following their index visit. Rates of referral were compared by sex, age, number of office visits, practice location and specialist type using t-tests or Pearson's correlation. Variance partitioning determined the proportion of variance in the overall referral rate accounted for by the practice and patient levels.
Results In total, 7771 patients (31.3%) had one or more referrals. The overall referral rate was 455/ 1000 patients/year (95% CI, 444_465). Rates were higher for females, older patients and rural practices. The referral rate correlated with thenumber of family physician office visits. Ninety-two percent of the total variance in referral rates was attributable to the patient (vs. practice) level.
Conclusions A Canadian primary care EHR database showed similar patterns of referral to those reported from administrative databases. Most variance in referral rates is explained at the patient level.


electronic health records; referrals; variance partitioning

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