Pre-referral laboratory completeness and diagnostic yield in an early arthritis clinic: a retrospective single-centre analysis

To characterise patients presenting to a specialised early arthritis clinic (EAC) at a German university rheumatology centre, and to analyse referral patterns, waiting times, pre-referral laboratory completeness, working diagnoses, serological markers, and independent associates of arthritis confirmation and DMARD initiation. Single-centre retrospective analysis of 290 consecutive patients. At each EAC appointment, a structured assessment comprising medical history, review of available laboratory results, focused physical examination, and arthrosonography was performed. Variables included demographics, serology (RF, anti-CCP), CRP, ESR, imaging, referral source, waiting time, and treatment decisions. Chi-squared, Mann–Whitney U, Kruskal–Wallis tests, and binary logistic regression were performed; p < 0.05 was considered significant. The cohort comprised 212 women (73.1%) and 78 men (26.9%), mean age 49.4 ± 15.9 years. Median waiting time was 23 days (Q1–Q3, 14–40). Although a complete baseline panel (RF, anti-CCP, CRP, ESR) was requested from referring physicians, it was available in only 110 patients (37.9%). Anti-CCP was missing in 34.5%, with missingness significantly associated with referral source (p = 0.013). Inflammatory arthritis was confirmed in 145 patients (50.0%) and DMARD initiation recommended in 130 (44.8%). In multivariable logistic regression (n = 163 with full serology), anti-CCP positivity was independently associated with arthritis confirmation (OR 4.25; 95% CI 1.68–10.74) and DMARD initiation (OR 4.49; 95% CI 1.80–11.22). Orthopaedist referral was independently associated with higher arthritis confirmation (OR 2.97; 95% CI 1.20–7.36). RF was not significantly associated with either outcome. EACs demonstrate high diagnostic yield for inflammatory joint disease. Anti-CCP positivity showed the strongest independent association with both outcomes. Pre-referral laboratory submission was achieved in fewer than 40% of patients despite being a stated referral requirement, with missingness associated with referral source. Targeted educational interventions for referring physicians are warranted.