Development and validation of a clinical prediction rule for bone marrow involvement in patients with Hodgkin lymphoma.

We developed a clinical prediction rule for bone marrow involvement (BMI) in Hodgkin lymphoma based on 826 patients and validated it in 654 additional patients. Independent prognostic factors for BMI were x1, B symptoms; x2, stage III/IV prior to bone marrow biopsy; x3, anemia; x4, leukocytes fewer than 6 x 10(9)/L; x5, age 35 years or older; and x6, iliac/inguinal involvement. Each factor was graded as x(i)=1, if present, or x(i)=0, if absent. A simplified score Zs=8x1+6x2+5x3+5x4+3x5+3x6-8 was assigned to each patient. The sensitivity, specificity, and positive and negative predictive value of this prediction rule was 97.8%, 51.5%, 10.6%, and 99.8%, respectively. In the validation group, they were 98.1%, 40.3%, 12.7%, and 99.6%. According to Zs value, 3 risk groups for BMI were defined: low risk (Zs<0, 44% of patients, 0.3% risk), standard risk (Zs, 0-9; 37% of patients; 4.2% risk), and high risk (Zs>or=10, 20% of patients, 25.5% risk). Patients with low risk (stage IA/IIA without anemia and leukopenia; stage IA/IIA, younger than 35 years, with either anemia or leukopenia but no inguinal/iliac involvement; and stage IIIA/IVA without any of these 4 risk factors) do not need bone marrow (BM) biopsy. Patients with standard risk should be staged with unilateral biopsy, but patients with high risk may benefit from bilateral biopsy.