Prognostic effect of comorbidities in patients with chronic myeloid leukemia treated with a tyrosine kinase inhibitor

Comorbidities at diagnosis among patients with chronic myeloid leukemia in chronic phase (CML‐CP) may affect their overall survival (OS) rate even in the tyrosine kinase inhibitor (TKI) era. However, the prognostic impact of comorbidities in patients with CML‐CP treated with a second‐generation TKI (2GTKI) has not been elucidated. We evaluated the effect of comorbidities on survival using the Charlson Comorbidity Index (CCI) in patients with CML‐CP treated with imatinib or a 2GTKI (nilotinib and dasatinib). From April 2010 to March 2013, 506 patients with CML‐CP were registered for the population‐based cohort study, and 452 with a median age of 56 y were assessable. Treatment groups included 139 patients receiving imatinib, 169 receiving nilotinib, and 144 receiving dasatinib. Comorbidities were diagnosed in 99 patients. CCI scores were stratified as follows: 2, 353 patients; 3, 72 patients; and ≥4, 27 patients. Treatment response did not vary relative to CCI scores. However, across the entire cohort, the OS rate was significantly lower among patients with higher CCI scores than in those with a CCI score of 2 (94.4% in score 2, 89.0% in score 3, and 72.8% in score ≥4; P < .001). Multivariate analysis identified a CCI score of ≥4 as a strong adverse prognostic factor for OS rather than the disease‐specific risk factor, older age, performance status, or selection of TKI (Wald test, P < .01). Our results demonstrated that comorbidities at diagnosis were the most important predictive factor for successful treatment, regardless of the TKI type used in CML‐CP. This trial was registered at UMIN‐CTR as 00003581.