Evaluating the impact of age and disease on survival of chronic lymphocytic leukaemia patients by a new method

Background: The impact of chronic lymphocytic leukaemia (CLL) on survival may be different in younger patients, but this remains controversial. Objectives: The aim of the study was to examine the effect of age on survival in CLL using an original method. Methods: Clinical, laboratory and survival data of 87 CLL patients treated in our institute were analysed. The survival of patients in different age groups was determined and compared, as related to the expected survival of age- and gender-matched general population obtained from national statistical data. Results: The mean age in the younger (≤ 65 years, n = 37) and older (> 65 years) age groups was 56 and 74 years (p < 0.001). The younger group had more unfavourable presentation, with advanced stage (Rai 2-4) in 46% vs. 16% (p = 0.002), and diffuse involvement of bone marrow in 60% vs. 18% (p = 0.03), compared with the older group, and were more likely to require treatment (p = 0.02). The Kaplan-Meyer curve showed a more favourable survival for the younger group. However, the loss of expected survival exposed a reversed pattern: while the older patients lost only 13%, the survival loss in the younger patients was 44% (p < 0.001). Conclusions: Chronic lymphocytic leukaemia had a more unfavourable presentation and a more severe clinical course in the younger patients. Our method of evaluating the negative impact of disease on expected survival reveals that their survival also is significantly more affected than that of older patients. We suggest calculating the loss of expected survival as a new criterion for assessing disease impact.