Background Allostatic load (AL) refers to the physiological burdens that arise from chronic stress response. A growing body of evidence suggests that AL may be associated with the development of chronic pain (CP). However, the prospective relationship between AL and CP has yet to be fully explored using population-based data. This study aimed to examine the prospective relationships between AL and CP using nationally representative data.

Data The study used two waves of nationally representative data from 945 adults aged 34–83 from the Midlife in the United States (MIDUS) study.

Methods The associations between AL in the MIDUS 2 Biomarker Project, computed using different indices, and three different measures of CP in the MIDUS 3 were examined, including the occurrence of chronic pain, the number of pain sites, and the severity of pain interference (PI). The associations were also examined in a subgroup of individuals with chronic primary pain (CPP). The analysis controlled for a range of sociodemographic variables, multiple chronic diseases, previous chronic pain onset, medication uses, mental illness, and adverse childhood experiences.

Results The study found that the AL index, defined using clinical cutoffs after square root transformation, was a predictor of PI approximately 7 years later among the CPP samples (β=0.448, 95% CI: 0.158, 0.737, p<0.01). The findings indicate that the AL index, defined using clinical norms, is a prospective risk factor for PI among individuals with CPP. This study provides evidence that the physiological burdens induced by stress may contribute to the development of CPP.