Higher Rates of Dysphagia Incidence Among Patients With Malignant Primary Brain Tumors Compared to Brain Metastases: A National Study of Medicare Beneficiaries

Introduction: Dysphagia occurs frequently with central nervous system (CNS) diseases. Additionally, rates of dysphagia increase with age. However, there are no population-based estimates of dysphagia among older patients with malignant primary brain tumors (PBTs) or brain metastases. Therefore, we aimed to describe the incidence of new-onset dysphagia among Medicare beneficiaries with CNS malignancies and compare rates of dysphagia between those with malignant PBTs and solid tumor brain metastases. Methods: Using the 2013-2018 Medicare 5% Data sample and ICD-9/10 codes, we identified beneficiaries at least 65 years of age with malignant PBTs as well as the five most common solid tumors metastasizing to the brain (lung, breast, melanoma, renal, and colorectal). Those with coexisting disorders predisposing to symptomatic dysphagia such as head and neck cancer, achalasia, or relevant neurological conditions, were excluded. We estimated rates of new onset dysphagia, defined as occurring within one year from the time of cancer diagnosis, among those with continuous Medicare enrollment for at least six months of follow-up time. Comparisons were made between 1) beneficiaries with malignant PBTs and those with brain metastases and 2) beneficiaries with brain metastases and their counterparts without CNS metastases. A Chi-squared test was used to assess differences between groups. Results: Of the 80,187 beneficiaries identified, the median age of all patients was 72 and most patients (64.9%) were female, primarily due to the large number of breast cancer patients in the cohort. There were 3,018 (3.8%) beneficiaries with malignant PBTs and 805 (1.0%) had brain metastases (Table). Dysphagia occurred in 3,396 (4.2%) of the overall population. Patients with malignant PBTs were significantly more likely to have dysphagia than those with brain metastases (9.7% vs 6.5%, p< 0.01). Patients with brain metastases were more likely to have dysphagia than those without CNS involvement (6.5% vs 4.0%, p< 0.01) (Figure). Conclusion: The incidence of dysphagia is high among older patients with CNS malignancies, with significantly higher rates among those with PBTs compared to brain metastases. The presence of CNS metastases among commonly occurring solid tumors is also associated with the development of dysphagia. These results warrant further investigation to identify predictors of dysphagia among this population as well as to describe its impact on clinical outcomes and overall health care utilization.Figure 1.: Rates of new onset dysphagia within one year of cancer diagnosis among Medicare beneficiaries by disease subgroups: primary brain tumors, solid tumors (lung, breast, melanoma, renal, and colorectal cancer) with brain metastases, and solid tumors without brain metastases. Table 1. - Clinical and demographic data among Medicare beneficiaries studied. #Primary tumor type by brain metastases are not reported to meet CMS censoring reporting requirements. Primary Brain Tumors (N=3,018) Solid tumors with brain metastases (N=805) Solid tumors without brain metastases (N=76,364) Age, median (Q1, Q3) 73 (68, 78) 71 (67, 76) 72 (67, 79) Female 1,672 (55.4%) 478 (59.4%) 49,866 (65.3%) RaceWhiteBlackOther 2,520 (83.5%)248 (8.2%)250 (8.3%) 671 (83.4%)9 (8.6%)65 (8.1%) 66,284 (86.8%)5,727 (7.5%)4,353 (5.6%) Primary tumor typeBreastColorectalLungMelanomaRenal -- --# 29,739 (38.9%)14,378 (18.8%)13,464 (17.6%)12,225 (16.0%)6,558 (8.6%) New onset dysphagia(within 1 year of cancer diagnosis) 293 (9.7%) 52 (6.5%) 3,055 (4.0%)