Effects of Allostatic Load on Long-Term Survival After Stroke

BACKGROUND: Allostatic load index (ALI) is often utilized to quantify the physiological response to stress. This study assesses the relationship between ALI and its impact on all-cause, cardiovascular, and stroke mortality in individuals with a self-reported history of stroke and within the general National Health and Nutritional Examination Survey sampled population. METHODS: Using data from the National Health and Nutritional Examination Survey (III, 1988-1994) and the 2015 Linked Mortality File, we selected adults aged ≥25 years with self-reported stroke. We computed the weighted prevalence of each ALI category to obtain nationally representative estimates with higher ALI corresponding to a higher stress burden. We evaluated the relationship between ALI category and mortality outcomes using the Cox proportional hazard model, considering the survey design variables and adjusting for age, sex, race/ethnicity, education, marital status, income, drinking, and smoking status. RESULTS: Of 17 284 people screened in the National Health and Nutritional Examination Survey sample population, 15 567 individuals were included in the study. The ALI distribution was 48.3% ALI ≤1, 21.7% ALI=2, and 30% ALI ≥3. Of 414 individuals with a reported history of stroke, there were 11.8% ALI ≤1, 22.1% ALI=2, and 66.1% ALI ≥3. There was an association between a higher ALI and older age, Black and Mexican American race, and >1 comorbidity in the overall sampled population. In the population with prior stroke, those with ALI ≥3 had 2.7× higher adjusted all-cause mortality (hazard ratio, 2.7 [CI, 1.5-4.9]) and 4.5× higher adjusted cardiovascular mortality (hazard ratio, 4.5 [CI, 1.4-14.3]) compared with those with ALI ≤1. In the general sampled National Health and Nutritional Examination Survey population, the ALI ≥3 group had 1.8× higher adjusted stroke mortality (hazard ratio, 1.8 [CI, 1.1-3.1]). CONCLUSIONS: Baseline higher ALI is associated with greater all-cause and cardiovascular mortality in stroke survivors and greater stroke mortality in the overall sampled National Health and Nutritional Examination Survey population.