Allostatic Load, Multimorbidity, and Overall and Cancer-Specific Survival among Older Adults in the United States

BACKGROUND: Both allostatic load (AL), a measure of cumulative physiological stress, and multimorbidity, the presence of multiple chronic conditions, have been linked to poorer survival in older adults; However, associations remain understudied. METHODS: Using the nationally representative National Health and Nutrition Examination Survey data from 1999-2018 with the 2019 Linked Mortality File, weighted Cox regression models estimated adjusted hazard ratios (HR) and 95% confidence intervals (CI) for the associations of AL and multimorbidity with overall and cancer-specific survival. AL consisted of nine biomarkers, assigning one point for each exceeding predefined clinically relevant cutoffs, for a total AL score (range:0-9; high AL ≥3). Multimorbidity was defined as having ≥2 of 11 chronic conditions. RESULTS: Participants (N= 3,484 adults ≥60 years with self-reported cancer) were on average 73 years old, 46% female, 71% non-Hispanic White, 59% had high AL, and 64% had multimorbidity. Overall, 46% of participants died of any cause, including 484 cancer-specific deaths. High AL and multimorbidity were both associated with poorer overall survival [HR (95% CI)=1.33 (1.15-1.54), 1.40 (1.21-1.62), respectively], and moderately for cancer-specific survival. Results were similar for sex-specific AL cutoffs, incorporating medication use, excluding individuals <65 years, and mutually adjusting for AL and multimorbidity. CONCLUSIONS: Among older adults with cancer, high AL and multimorbidity are associated with poorer overall survival. Interventions that improve chronic condition management may reduce AL and multimorbidity and improve survival for older cancer survivors. IMPACT: Assessing AL, and multimorbidity could help identify high-risk older cancer survivors, and inform survivorship care.