Validation of the Behçet's Syndrome Overall Damage Index (BODI) for Retrospective Studies and a Proposal for Modification.

Objective: Assessment of damage accrual over time is important for evaluating and comparing long-term results of treatment modalities and strategies. Retrospective studies may be useful for assessing long-term damage, especially in rare diseases. We aimed to validate Behçet's Syndrome Overall Damage Index (BODI) for use in retrospective studies by evaluating its construct validity, reliability, and feasibility in retrospectively collected data. Additionally, we aimed to determine missing items by evaluating Behçet's syndrome patients with different types of organ involvement and long-term follow-up.

Methods: We included 300 patients who had at least 2 clinic visits at 1-year intervals. The construct validity for use in retrospective trials was assessed by comparing BODI scores calculated from patient charts and during face-to-face visits. BODI was additionally scored using retrospective chart data by 2 different observers and by the same observer six months apart, in a blinded manner. The time for filling BODI was evaluated to assess feasibility. Additionally, damaged items that were missing from BODI were identified.

Results: There was a good correlation between the retrospective and face-to-face evaluation of BODI (ICC 0.99; %95 CI 0.99-0.99). Inter-observer and intra-observer agreement were good (ICC 0.96 and 1, respectively). The main damage items that BODI did not capture were hypertension, liver failure, lung parenchymal involvement, glaucoma, and lymphedema.

Conclusion: BODI seems to be a reliable and feasible instrument for assessing damage in retrospective studies. Modifying BODI using the additional damage items identified in this study may make it an even better scale.