The Prevalence of Diffuse Large B-Cell Lymphoma Varies Substantially by Methods Applied: Results From a...

Accurate prevalence estimates of diffuse large B-cell lymphoma (DLBCL) are important for numerous purposes including orphan drug designation. A key criterion for orphan drug designation is a disease prevalence of less than 5/10,000 persons. The objective is to apply and compare different methods of prevalence assessment.

In the present nationwide Danish cohort study, the prevalence of DLBCL was assessed using different methodologies, including register-based and formula-based approaches.

The prevalence calculations were based on 9,492 patients diagnosed with DLBCL since year 2000. Incidence increased and survival improved in the period, resulting in higher prevalence of DLBCL. In year 2023, the 2-,3-,5-,10-, and 20-year prevalences were 1.53, 2.19, 3.45, 6.08, and 8.80 per 10,000 adults using the register-based approach. The formula-based approach was generally accurate when using restricted mean survival. However, when using median survival, the total prevalence was estimated at 8.1 per 10,000 adults. Furthermore, when extrapolating the median survival from the 5-year survival under constant hazard assumption as done in some orphan drug designation reports, the prevalence was estimated at 6.6 per 10,000 adults.

In conclusion, the estimated DLBCL prevalences are sensitive to the applied method. DLBCL would disqualify from orphan drug designation in some of the mentioned scenarios.