Diagnostic Yield of Internal Medicine Referrals to Rheumatology: A Retrospective Single-Center Study

Background and Objectives: In Turkey, access to adult rheumatology outpatient clinics requires referral from another specialty, mostly internal medicine, and no standardized referral algorithms are in use. We estimated the diagnostic yield of new inflammatory rheumatic disease (IRD) diagnoses among internal medicine referrals who completed rheumatology evaluation and identified referral-stage characteristics associated with a new IRD diagnosis. Materials and Methods: In this retrospective cohort study, 2233 patients referred from internal medicine clinics to rheumatology outpatient clinics between 1 September and 30 November 2022 were screened. Patients with a prior diagnosis of IRD (n = 539) and those who did not attend their scheduled appointment (n = 732) were excluded, leaving 962 patients who completed rheumatology evaluation for analysis. Findings documented at referral were compared between patients with and without a new IRD diagnosis, and associations were examined with a clinically selected multivariable logistic regression model without laboratory variables, because laboratory tests had been ordered selectively. Results: Among the 962 patients who completed rheumatology evaluation, 141 (14.6%) received a new IRD diagnosis, corresponding to 6.3% of all 2233 referrals; the diagnostic status of the 732 patients who did not attend is unknown. In the multivariable model, swollen and tender joints were associated with a new IRD diagnosis (odds ratio [OR] 5.24, 95% confidence interval [CI] 3.17–8.68), whereas sicca symptoms (OR 1.45, 95% CI 0.83–2.55) and constitutional symptoms (OR 1.66, 95% CI 0.76–3.64) were not independently associated. Conclusions: Among patients referred from internal medicine to a tertiary rheumatology clinic who completed evaluation, approximately one in seven received a new IRD diagnosis. Referral appropriateness was not assessed, and the high non-attendance rate limits generalization to all referrals. Swollen and tender joints were the only referral characteristic independently associated with a new diagnosis. Whether structured referral criteria, medical education, or triage strategies improve the yield of referrals is a hypothesis for prospective evaluation.