Multimorbidity and dynamic transitions of low back pain states in older adults: a multistate markov analysis of the health and retirement study

Low back pain is an important contributor to disability and reduced healthy life expectancy in older adults. Most previous studies have examined prevalence or single outcomes, with limited attention to transitions across pain severity states and death. This study characterized low back pain state transitions among older adults in the United States and assessed the impact of chronic disease burden. Longitudinal data from the Health and Retirement Study (HRS) collected between 2006 and 2018 were analyzed. Participants were included in the analytic cohort if they contributed at least two chronologically ordered state records, including either two living-state records or one living-state record followed by death. Low back pain states were defined by pain severity and death status, and chronic disease burden was classified by the number of chronic conditions. Continuous-time multistate Markov models were used to estimate transition-specific hazards, transition probabilities, and state-specific sojourn times. Among 9,820 adults aged > 60 years, 21,335 state records were included. Low back pain showed dynamic transitions involving progression, recovery, and death. Compared with disease-free participants, those with multimorbidity had a higher hazard of transition from no low back pain to mild low back pain (HR, 1.66; 95% CI, 1.27–2.17) and a lower hazard of transition from moderate-to-severe low back pain to mild low back pain (HR, 0.27; 95% CI, 0.09–0.83). Multimorbidity was also associated with higher hazards of death from both the no low back pain and moderate-to-severe low back pain states. For a common covariate profile, the model-estimated mean sojourn time in the no low back pain state was shorter in the multimorbidity group than in the disease-free group (6.94 years [95% CI, 6.02–8.00] vs 14.68 years [95% CI, 12.04–17.91]). Low back pain in older adults showed clear dynamic transitions across severity states and death. Multimorbidity was associated with increased hazards of incident low back pain and death, a lower likelihood of recovery, and a shorter low-back-pain-free survival. Older adults with multimorbidity should be prioritized in integrated strategies for low back pain prevention and management.