Multimorbidity and competing risks for incident dementia and dementia‐free death in an ADRC cohort

Abstract

AbstractBackgroundOlder adults are often affected by more than one coexisting chronic disease, a condition referred to as multimorbidity. Multimorbidity associates with poor physical and mental health outcomes, cognitive decline, and higher mortality. This study aims to assess the association between the number of self‐reported chronic conditions (CC) and risks for dementia and dementia‐free death in a cohort of older adults.MethodWe examined data from the University of Kentucky Alzheimer’s Disease Research Center cohort, a convenience sample of community‐based older adults followed longitudinally until death. Adults ≥50 years with normal cognition at baseline and data available on 11 measured CC and mental and physical components of SF‐36 (health‐related quality of life measure) were included in this study. The cohort was stratified at baseline based on self‐reported CC into 3 groups: 0, 1, and ≥2. A competing risk analysis using Fine‐Gray subdistribution hazard models was performed to estimate associations between the number of comorbidities and incident dementia or dementia‐free death.ResultAmong 772 adults (mean age 73.1±6.7 years, 66.6% female, 89.0% white), a majority (64.4%) reported ≥2 of the measured 11 CC at baseline; 22.8% had one, and 12.8% had none (Figure 1). These groups did not significantly differ in main demographic characteristics (Table 1). Individuals with multimorbidity had lower physical component scores of SF‐36 indicating worse self‐perceived physical health than other groups. Almost half (45.9%) of the overall cohort reported a history of smoking, which was most common in the ≥2 CC group. Unadjusted and adjusted Fine‐Gray models did not show an association between the number of CC at baseline and incident dementia, accounting for competing risk of death during mean 6.8±3.9 annual follow‐up visits. There was a significant association between the number of CC at baseline and dementia‐free death, accounting for competing event dementia, in unadjusted analyses; this association did not remain significant in the adjusted analyses(Table 2).ConclusionMultimorbidity is prevalent in this cohort of older adults. When accounting for competing risks of death, the number of CC was not associated with incident dementia. Further studies are needed to examine associations with mild cognitive impairment and cognitive decline.