The Symptom Burden of Chronic Myelogenous Leukemia (CML)

Symptom burden is the combined impact of all disease-related and therapy-related symptoms on one’s ability to function as one did before onset of disease or therapy. Lack of understanding of symptoms may result in failure to address symptoms and return patients to optimum functioning. This is critical for patients with chronic diseases who are receiving continuing therapy, such as patients with chronic myeloid leukemia (CML). Additionally patient-reported outcome measures are becoming primary endpoints in clinical trials to test results such as reduction in symptom burden that establish treatment benefits from the patient’s perspective. No patient-reported outcome measure for CML currently exists, and there is little understanding or knowledge of the symptom burden of CML and its treatment. The purpose of this study was to initially explore the symptom burden of CML.

Methods: Retrospective analysis of 29 patients with CML who participated in two larger cross-sectional studies exploring cancer-related symptoms. Patients used the M. D. Anderson Symptom Inventory (MDASI) to rate the severity of their symptoms (13 items) and the degree to which their symptoms interfered with daily living (6 items) on a 0–10 scale.

Results: Patient/treatment characteristics are summarized in Table 1.

Table 1: Patient/Treatment Characteristics

Mean global symptom severity was 1.86 (SD 1.76) and mean global interference was 1.79 (SD 2.05). Cronbach alpha for the symptom scores was 0.916 and for the interference scores was 0.922, indicating that the MDASI is reliable in this sample. The 6 most severe symptoms (mean severity score > 2.5) were fatigue, drowsiness, lack of appetite, disturbed sleep, difficulty remembering things, and dry mouth. Symptoms interfered most with work and general activities. Mean symptom severity scores and standard deviations for the top most severe symptoms and most bothersome interference items are reported in Table 2.

Table 2: Symptom and Interference Means and SD

There was no significant difference in mean symptom severity or interference between patients receiving interferon-based therapies and patients receiving tyrosine kinase inhibitors. There were significant differences in mean symptom severity (p = .001) and interference (p < .001) scores between patients with good (0 or 1) and poor (≥ 2) ECOG performance status. Preliminary analysis has encouraged us to investigate further relationships among the 13 symptom items, the 6 interference items, and demographic, disease, and treatment related factors. This further, more-detailed analysis will be presented.

Conclusion: Methods for patients with CML to report symptom burden to clinicians and researchers are needed. Based on preliminary results, the MDASI is a reliable instrument that captures many symptoms of CML and differentiates between levels of severity of illness. Further work is ongoing to identify and add symptom items to the MDASI that will capture CML-specific and treatment-specific symptoms.