Cox regression analysis for time to progression by baseline parameter. Vertical lines represent no treatment effect; risk ratio equals 1. Horizontal bars represent 95% confidence intervals for relevant category. Model includes stratification by center pool. BNLI indicates British National Lymphoma Investigation Group; BM, bone marrow; CRF, case report form; FLIP Index, Follicular Lymphoma International Prognostic Index; LDH, lactate dehydrogenase; B2M, β₂ microglobulin; and IPI, International Prognostic Index.