(24) The Burden of Sudden Cardiac Death Among Older Adults Diagnosed with Cancer

Publication Number: 355

Background: Several new classes of cancer therapies (e.g., tyrosine kinase inhibitors) and supportive care medications (e.g., certain antiemetics) can delay ventricular repolarization, manifesting as QT interval prolongation on electrocardiogram, which is associated with ventricular tachyarrhythmias and sudden cardiac death (SCD). Older adults with cancer are at elevated risk for these adverse outcomes due to the high prevalence of comorbid cardiovascular disease and polypharmacy. Yet, few studies have quantified the incidence of SCD among older adults with cancer.

Objectives: We estimated the 6-, 12-, and 24-month incidence of SCD among a cohort of older adults newly diagnosed cancer, overall and by age, sex, and cancer type.

Methods: We identified all individuals aged 65 years or older with one of 21 solid tumors diagnosed between 2004 and 2017 using the Surveillance, Epidemiology, and End Results (SEER) program cancer registries. Using linked Medicare enrollment data, we required all individuals to have continuous enrollment in Medicare Parts A and B (and no managed care enrollment) for up to 24 months following diagnosis (or until death, whatever occurred first). SCD was defined using a modification of the algorithm developed by Chung et al using place of death codes from medical claims and ICD-10 cause of death codes. We used the Aalen-Johansen estimator to calculate the 6-, 12-, and 24-month cumulative incidence of all-cause mortality and SCD, overall and by age, sex, and cancer type. In SCD analyses, death due to a cause other than SCD was treated as a competing event. We used bootstrapping with 200 replicates to estimate 95% confidence intervals.

Results: There were 1,702,758 older adults with cancer included in the study population; the median age was 75 years; 49% were female; and the most common cancer types were lung (16.6%), prostate (15.6%), breast (13.6%), and colorectal cancer (10.6%). At 6-, 12-, and 24-months, the cumulative incidence of all-cause mortality was 21.1% (95% CI: 21.1%, 21.2%), 29.1% (95% CI: 29.0%, 29.2%), and 38.0% (95% CI: 37.9%, 38.1%). At the same time points, the cumulative incidence of SCD was 0.05% (95% CI: 0.046%, 0.052%), 0.075% (95% CI: 0.071%, 0.079%), and 0.11% (95% CI: 0.109%, 0.120%), respectively. The cumulative incidence of SCD at 24-months was highest among those aged 85+ years, males, and those diagnosed with colorectal (0.153%) or lung cancer (0.115%).

Conclusions: While a rare event among older adults with cancer, SCD occurs more frequently among adults aged 85+, with colorectal or lung cancer, and males. Using large healthcare databases, like SEER-Medicare, may allow researchers to evaluate the risk of SCD associated with cancer treatments and supportive care medications.