Longitudinal associations of chronic pain severity trajectories and number of pain site trajectories with risk of limitations in ability in daily activities: Evidence from two 10-year prospective cohort studies.

Persistent high-level chronic generalized pain severity trajectory was associated with the highest risk of ADL limitations among generalized pain trajectory groups.

• Analysis was conducted using Cox proportional hazards models on longitudinal data from adults aged 50 and above.
• Two cohorts were used: the English Longitudinal Study of Ageing (ELSA) and the Korean Longitudinal Study of Aging (KLoSA).
• Both persistent high-level pain and worsening pain trajectory groups showed the highest increased risk of ADL limitations.
• Dynamic changes in pain severity states were tracked over 10-year prospective follow-up periods.

All trajectories of the number of pain sites were positively associated with ADL limitation risk, with the increasing number of pain sites trajectory showing the strongest association.

• The increasing number of pain sites trajectory had HR = 2.738 (95% CI: 2.147–3.492).
• All pain site number trajectories were positively associated with ADL limitation risk.
• The increasing trajectory showed the strongest association among all pain site trajectory groups.
• Number of pain sites trajectories were identified by analyzing dynamic changes in pain severity states across sites.

Worsening pain trajectory groups for site-specific pain at the back, feet, and knees also exhibited the highest increased risk of ADL limitations.

• Site-specific pain locations analyzed included back, feet, and knees.
• Among trajectories of chronic site-specific pain severity, persistent high-level pain and worsening pain groups showed the highest ADL limitation risk.
• Findings were consistent across both the ELSA and KLoSA cohorts.
• Cox proportional hazards models were used to assess these associations.

Depression mediated the associations between various pain severity trajectories and ADL limitations.

• Mediation analysis was conducted to investigate the mediating role of depression.
• Depression mediated associations between chronic generalized pain severity trajectories and ADL limitations.
• Depression also mediated associations between site-specific pain severity trajectories (back, feet, knees) and ADL limitations.
• The mediating effect of depression was examined across multiple trajectory types including number of pain sites trajectories.

The study utilized longitudinal data from two prospective cohorts of adults aged 50 and above followed over 10-year periods.

• Cohorts included the English Longitudinal Study of Ageing (ELSA) and the Korean Longitudinal Study of Aging (KLoSA).
• Participants were aged 50 and above at baseline.
• Follow-up duration was 10 years for both cohorts.
• Pain severity trajectories were identified by analyzing dynamic changes in pain severity states over time, addressing limitations of single time-point assessments used in prior studies.

Previous studies have mostly assessed pain severity at a single time point, overlooking temporal variability in chronic pain.

• The study was motivated by the gap in longitudinal pain trajectory research in relation to ADL limitations.
• Chronic pain is identified as a significant risk factor for limitations in activities of daily living (ADL).
• The authors argue that incorporating longitudinal monitoring of chronic pain severity trajectories into ADL function limitation management programs is crucial.
• This study aimed to address the gap by exploring longitudinal associations between pain trajectories and ADL limitation risk.