Factors Impacting Mortality in Chronic Lymphocytic Leukemia

A study presented at the 2020 ASH Annual Meeting found that most patients with chronic lymphocytic leukemia (CLL) die from causes unrelated to their cancer. The study indicates certain patient factors were associated with worse prognosis.

Researchers used Surveillance, Epidemiology, and End Results-Medicare data to identify 12,687 patients ≥66 years who were diagnosed with primary CLL between 2004 and 2015. Researchers also assessed a patient cohort who initiated CLL-directed therapy after diagnosis (treated cohort; n=1,543). In both cohorts, patients were required to have continuous enrollment in Medicare Parts A and B and no managed care during the year post-diagnosis. The treated cohort was also required to have continuous enrollment in Medicare Part D if they initiated treatment on or after Jan. 1, 2007.

Researchers used a landmark approach that only included patients who survived at least one year following diagnosis. Among treated patients, only those who initiated treatment within one year of diagnosis were included. Patients were followed for CLL-specific and other-cause mortality from the landmark until Dec. 31, 2016.

Mean age at diagnosis was 77 years, and 45% were female. Patients were categorized as having low (46%), medium (26%), and high (28%) comorbidity. The most common comorbidities were uncomplicated diabetes (25%), chronic pulmonary disease (17%), and congestive heart failure (14%). Twenty-six percent of patients had a high probability of being frail. The treated cohort had slightly more patients categorized as having medium (30%) and high (34%) comorbidity, as well as high predicted probability of frailty (30%).

Overall, 10-year cumulative incidence of mortality was 69% (95% confidence interval [CI], 67-70). Ten-year incidence of mortality was 82% (95% CI, 79-85%) in the treated cohort, with most deaths attributed to non-CLL causes.

Older age at diagnosis, earlier year of cancer diagnosis, higher predicted frailty, and higher comorbidity were associated with worse prognosis. There were stronger associations between frailty and comorbidity and other-cause mortality (high vs. low frailty: hazard ratio [HR], 2.20 [95% CI, 2.00-2.43]; high vs. low comorbidity: HR, 2.00 [95% CI, 1.85-2.17]) than their associations with CLL-specific mortality (high vs. low frailty: HR, 1.43 [95% CI, 1.20-1.70]; high vs. low comorbidity: HR, 1.07 [95% CI, 0.93-1.24]).

“CLL-directed treatment decision-making in older adults should explicitly consider age-related health conditions, such as comorbidity and frailty, as they are strongly and independently associated with prognosis,” the researchers concluded.

Reference

Duchesneau ED, McNeill AM, Tyczynski JE, et al. Prognosis of Older Adults with Chronic Lymphocytic Leukemia By Comorbidity and Frailty: A SEER-Medicare Cohort Study. Abstract 1645. Presented at the 62nd American Society of Hematology Annual Meeting & Exposition, Dec. 2-11, 2020.