Abstract
INTRODUCTION: Falls are a major source of morbidity in older adults and pose particular concern in cancer survivors who may experience treatment related neurological and functional decline. Dementia is a known risk factor for falls, yet its contribution to fall risk among breast cancer survivors has not been well defined. METHODS: This retrospective cohort study used de identified electronic health records from the TriNetX Research Network, which includes more than 100 health care organizations. Women aged 65 years or older with stage 1 to stage 3 breast cancer were eligible. Dementia was identified using ICD 10 code F03 recorded on or after the first qualifying cancer diagnosis. Propensity score matching used a 1 to 1 nearest neighbor approach. The primary outcome was incident fall events identified by ICD 10 codes for unspecified falls, initial fall encounters, history of falling, and repeated falls. Multivariable Cox proportional hazards models estimated independent predictors of falls. Follow up began 1 day after diagnosis and continued through the last recorded encounter. RESULTS: A total of 49 576 breast cancer survivors met inclusion criteria, of whom 1 683 (3.4%) had dementia. Before matching, fall related diagnoses were significantly more common in patients with dementia, including unspecified falls (26% vs 2%, p < 0.0001) and history of falling (15% vs 1%, p < 0.0001). After 1 to 1 matching, 1 602 survivors remained in each cohort with standardized mean differences < 0.06 across all variables. During follow up, 17.8% of survivors with dementia experienced a fall compared with 6.5% without dementia. This corresponded to an absolute risk difference of 11.3% (95% CI 9.1% to 13.6%), a risk ratio of 2.74 (95% CI 2.41 to 3.12), and an odds ratio of 3.12 (95% CI 2.67 to 3.65). The Kaplan Meier analysis showed significantly lower fall free survival in the dementia cohort (log rank p < 0.0001). The adjusted Cox model showed that dementia remained an independent predictor of falls (hazard ratio 1.43, 95% CI 1.25 to 1.63). Additional strong predictors included long term drug therapy (hazard ratio 2.62, 95% CI 2.41 to 2.84), osteoporosis (hazard ratio 1.48, 95% CI 1.34 to 1.62), polyneuropathy (hazard ratio 1.58, 95% CI 1.34 to 1.85), and depressive episode (hazard ratio 1.78, 95% CI 1.60 to 1.98). CONCLUSIONS AND RELEVANCE: Dementia was associated with a substantially elevated fall risk among older breast cancer survivors, even after extensive adjustment for comorbidity, neurological conditions, psychiatric disorders, and medication burden. Recognition of this risk may help clinicians identify a subgroup of survivors who require closer monitoring and more precise evaluation during routine care.