U-shaped association of red cell distribution width to platelet count ratio and prognosis in diffuse large B-cell lymphoma treated with rituximab-based therapy.

[OBJECTIVES] To examine the nonlinear association between the red cell distribution width to platelet count ratio (RPR) and the prognosis of diffuse large B-cell lymphoma (DLBCL) patients treated with rituximab-based therapies.

[METHODS] Data from 170 newly diagnosed DLBCL patients on rituximab regimens were retrospectively analyzed. Clinical data and survival outcomes were collected. Patients were categorized into three RPR tertiles: Tertile 1 (<0.048), Tertile 2 (0.048-0.066), and Tertile 3 (0.066). Multivariable Cox models were used to evaluate the RPR's impact on progression-free survival (PFS) and overall survival (OS). Nonlinear RPR-PFS/OS relationships were explored using smooth curve fitting and a two-piecewise Cox model.

[RESULTS] Over a median follow-up of 30.5 (range: 3-92) months, there were 42 deaths and 67 events (death or progression). Patients in the first and third RPR tertiles had a higher risk of poorer PFS compared to the second RPR tertile. A U-shaped relationship was found between RPR and PFS, with an inflection point at an RPR level of 0.051. For PFS, the HR per 0.01 increment was 0.58 (0.39, 0.87) on the left and 1.10 (1.01, 1.19) on the right of this point ( < 0.05).

[CONCLUSION] Both low and high RPR levels are linked to reduced PFS, confirming a U-shaped association.