Chronic Myeloid Leukemia in Nigerian Patients: Anemia is an Independent Predictor of Overall Survival

OBJECTIVES: The advent of the tyrosine kinase inhibitors has markedly changed the prognostic outlook for patients with Ph+ and/or BCR-ABL1(+) chronic myeloid leukemia (CML). This study was designed to assess the overall survival (OS) of Nigerian patients with CML receiving imatinib therapy and to identify the significant predictors of OS. METHODS: All patients with CML receiving imatinib from July 2003 to June 2013 were studied. The clinical and hematological parameters were studied. The Kaplan-Meier technique was used to estimate the OS and median survival. P-value of <0.05 was considered as statistically significant. RESULTS: The median age of all 527 patients (male/female = 320/207) was 37 (range 10-87) years. There were 472, 47, and 7 in chronic phase (CP), accelerated phase, and blastic phase, respectively. As at June 2013, 442 patients are alive. The median survival was 105.7 months (95% confidence interval [CI], 91.5-119.9); while OS at one, two, and five years were 95%, 90%, and 75%, respectively. Multivariate Cox regression analysis revealed that OS was significantly better in patients diagnosed with CP (P = 0.001, odds ratio = 1.576, 95% CI = 1.205-2.061) or not in patients with anemia (P = 0.031, odds ratio = 1.666, 95% CI = 1.047-2.649). Combining these variables yielded three prognostic groups: CP without anemia, CP with anemia, and non-CP, with significantly different median OS of 123.3, 92.0, and 74.7 months, respectively (chi(2) = 22.042, P = 0.000016). CONCLUSION: This study has clearly shown that for Nigerian patients with CML, the clinical phase of the disease at diagnosis and the hematocrit can be used to stratify patients into low, intermediate, and high risk groups.