Pain trajectory and risk of incident chronic lung disease among middle-aged and older adults: a longitudinal study in China

Abstract Background Chronic pain is an established risk factor for chronic lung disease (CLD). However, previous studies have mainly focused on pain intensity or the number of pain sites, with limited attention to long-term pain trajectories. This study aimed to investigate the associations of pain status, longitudinal pain transitions and trajectories, and cumulative pain exposure with incident CLD. Methods Data were obtained from the China Health and Retirement Longitudinal Study (CHARLS), including participants aged ≥ 45 years. Pain was assessed longitudinally using four approaches: baseline pain status (2015), pain status transitions (2015–2018), long-term pain trajectories (2015–2020), and cumulative pain exposure. Incident CLD was followed through 2020. Multivariable Cox proportional hazards models were used to evaluate associations of baseline pain status and pain transitions with CLD risk, while logistic regression models assessed associations of long-term pain trajectories and cumulative pain exposure with CLD risk. Sensitivity analyses were conducted to test robustness. Results Baseline pain was significantly associated with increased CLD risk (HR 1.25, 95% CI 1.10–1.42). Compared with stable pain-free participants, those with progressive pain or persistent pain had higher CLD risk in transition analyses (Pain-free to pain: HR 1.51, 95% CI 1.13–2.03; Persistent pain: HR 1.69, 95% CI 1.24–2.31). Similarly, trajectory analyses showed elevated odds of CLD among participants with progressive pain (OR 2.40, 95% CI 1.79–3.22; RR 2.31, 95% CI 1.74–3.05) and persistent pain (OR 2.93, 95% CI 2.04–4.20; RR 2.76, 95% CI 1.95–3.89), while the association with intermittent pain was only borderline significant (OR 1.43, 95% CI 1.00–2.03; RR 1.41, 95% CI 1.00–1.99). Pain remission was not associated with increased CLD risk in either transition or trajectory analyses. A significant dose-response relationship was observed between cumulative pain exposure and the odds of CLD ( P for trend < 0.001), with the highest odds among participants reporting three pain episodes (OR 3.15, 95% CI 2.20–4.52; RR 2.96, 95% CI 2.10–4.17). Conclusions Long-term dynamic patterns of pain are independently associated with incident CLD. Pain progression, persistence, and greater cumulative pain exposure are associated with a higher likelihood of CLD, whereas pain remission is not associated with excess risk.