The Pace of Biological Aging Partially Explains the Relationship Between Socioeconomic Status and Chronic Low Back Pain Outcomes

Introduction: Having a lower socioeconomic status (SES) is a predictor of age-related chronic conditions, including chronic low back pain (cLBP). We aimed to examine whether the pace of biological aging mediates the relationship between SES and cLBP outcomes - pain intensity, pain interference, and physical performance. Methods: We used the Dunedin Pace of Aging Calculated from the Epigenome (DunedinPACE) software to determine the pace of biological aging in adults ages 18 to 85 years with no cLBP (n = 74), low-impact pain (n = 56), and high-impact pain (n = 77). Results: The mean chronological age of the participants was 40.9 years (SD= 15.1); 107 (51.7%) were female, and 108 (52.2%) were Black. On average, the pace of biological aging was 5% faster [DunedinPACE = 1.05 (SD = 0.14)] in the sample (DunedinPACE value of 1 = normal pace of aging). Individuals with higher levels of education had a significantly slower pace of biological aging than those with lower education levels (F = 5.546, p = 0.001). After adjusting for sex and race, household income level significantly correlated with the pace of biological aging (r = -0.17, p = 0.02), pain intensity (r = -0.21, p = 0.003), pain interference (r = -0.21, p = 0.003), and physical performance (r = 0.20, p = 0.005). In mediation analyses adjusting for sex, race, and body mass index (BMI), the pace of biological aging mediates the relationship between household income (but not education) level and cLBP intensity, interference, as well as physical performance. Discussion: Results indicate that lower SES contributes to faster biological aging, possibly contributing to greater pain intensity and interference, as well as lower physical performance. Future interventions slowing the pace of biological aging may improve cLBP outcomes. Pain language summary: Individuals of lower socioeconomic status (SES) experience worse outcomes from age-related chronic conditions, including chronic low back pain (cLBP). This work examines the relationship between SES, pace of biological aging, and cLBP intensity, interference with daily activities, and physical function. Lower SES correlates with a faster pace of biological aging, as well as cLBP pain intensity, pain interference, and physical performance. The pace of biological aging helps explain the relationship between household income and cLBP intensity, interference, as well as physical performance. Interventions targeting SES disparities may slow biological aging and improve cLBP outcomes.