Age-Specific Modifiable Determinants and Nonlinear Risk Patterns of Habitual Low Back Pain in a Large Medical Check-Up Cohort: A Cross-Sectional and Longitudinal Analysis.

Abstract

Age-related mechanisms underlying habitual low-back pain (LBP) remain poorly defined, with most studies pooling heterogeneous populations and lacking behavioral granularity. To identify modifiable and age-specific determinants of habitual LBP using a nationwide health check-up cohort, and to examine their longitudinal stability in within-person models. Cross-sectional analysis with longitudinal sub analysis of repeat examinees from a large academic preventive medicine program in Japan (2020-2023). 13,135 adults (≤ 40 years: n = 2,034; ≥ 50 years: n = 8,354), excluding transitional 41-49 age group; 7,215 repeat attendees contributed 8,268 visits for longitudinal analysis. Self-reported habitual LBP (pain on most days ≥ 1 month) assessed via standardized questionnaire. Participants completed a 279-item lifestyle survey and laboratory panel. Multivariable logistic models were constructed separately by age group using forced-entry selection (p < 0.20), incorporating restricted cubic splines for body fat percentage. Conditional logistic regression and generalized estimating equation (GEE) models assessed within-person and population-level effects. In young adults, higher body fat, lower HDL-C, chewing difficulty, frequent animal-fat intake, and non-restorative sleep increased LBP risk; moderate sweat-inducing exercise was protective. In older adults, age, elevated LDH, low platelet count, smoking, overeating, and poor sleep were risk factors, while exercise and brisk gait were protective. In longitudinal models, non-restorative sleep remained the strongest within-person driver (OR 6.3). Body fat effects were non-linear, with a steep threshold beyond ∼40 %. Modifiable behaviors, particularly sleep and physical activity, are associated with habitual LBP risk across age strata. The distinct behavioral and biological signatures may support implementing age-stratified, evidence-informed prevention within routine check-ups.