Allostatic load and risk of all-cause, cancer-specific, and cardiovascular mortality in older cancer survivors: an analysis of the National Health and Nutrition Examination Survey 1999-2010

Background: Allostatic load has been linked to an increased risk of death in various populations. However, to date, there is no research specifically investigating the effect of allostatic load on mortality in older cancer survivors.

Aims: To investigate the association between allostatic load (AL) and mortality in older cancer survivors.

Method: A total of 1,291 adults aged 60 years or older who survived for ≥1 year since cancer diagnoses were identified from the 1999-2010 National Health and Nutrition Examination Survey. AL was the exposure of interest incorporating 9 clinical measures/biomarkers; one point was added to AL if any of the measures/biomarkers exceeded the normal level. The sum of points was categorized as an ordinal variable to reflect low, moderate, and high AL. Our outcomes of interest were all-cause, cancer-specific, and cardiovascular disease (CVD)-specific mortality. Death was identified by linkage to the National Death Index. Multivariable Cox proportional hazards models were used to estimate adjusted hazard ratio (aHR) and 95% confidence intervals (CI) of mortality by AL category.

Results: Overall, 53.6% of participants were male and 78.4% were white. The mean age of study participants at interview was 72.8 years (SD=7.1). A total of 546 participants died during the follow-up (median follow-up time: 8.0 years). Among them, 158 died of cancer and 106 died of cardiovascular events. Results from multivariable Cox proportional hazards models showed that higher ALS was positively associated with higher all-cause mortality (ALS=4-9 vs. ALS =0-1: aHR=1.52, 95% CI =1.17-1.98, p-trend<0.01) and higher cancer-specific mortality (ALS=4-9 vs. ALS =0-1: aHR=1.80, 95% CI =1.12-2.90, p-trend=0.01). The association between ALS and cardiovascular mortality was positive but non-significant (ALS=4-9 vs. ALS =0-1: aHR=1.59, 95% CI =0.86-2.94, p-trend=0.11).

Conclusions: Our study suggests that older cancer survivors can have a higher risk of death if they have a high burden of AL.