Timing matters: diagnostic delay and major organ involvement in Behçet's syndrome

To assess the association between diagnostic delay and major organ involvement (MOI) in Behçet's syndrome (BS), accounting for time at risk and heterogeneity in disease trajectories.

We conducted a retrospective monocentric cohort study including 173 patients with BS fulfilling ISG and/or ICBD criteria and with at least 5 years of follow-up. Patients were classified according to the presence or absence of MOI (ocular, neurological, gastrointestinal, or vascular involvement). Diagnostic delay was defined as the time from symptom onset to diagnosis. Logistic regression and sensitivity models assessed the association between diagnostic delay and cumulative MOI, accounting for age at onset, sex, and disease duration. Time-to-event analyses were performed among patients without MOI at disease onset to evaluate incident MOI during follow-up.

Among 173 patients, 101 (58.4%) had at least one cumulative MOI. Timing of first MOI was available for 100 patients: 67 had MOI already present at disease onset, whereas 33 developed incident MOI during follow-up. Diagnostic delay was longer in patients with cumulative MOI than in those without MOI. In the initial logistic regression model adjusted for age at onset and sex, diagnostic delay was associated with cumulative MOI; however, this association was attenuated after accounting for disease duration. Time-to-event analysis among patients without MOI at disease onset did not show a statistically significant association between diagnostic delay and incident MOI.

Diagnostic delay was associated with cumulative MOI in BS; however, this association was attenuated after accounting for disease duration and time at risk. The findings support the existence of heterogeneous disease trajectories, including early severe disease, incident MOI during follow-up, and absence of MOI over the observed period. These results should be interpreted as hypothesis-generating and require confirmation in prospective longitudinal studies.