As the global population ages, frailty and pain have become two significant health issues that impact the quality of life in older adults. Previous studies have not thoroughly explored the relationship between them. This study aims to investigate the longitudinal association between frailty and pain using data from prospective cohorts in China (CHARLS), the United Kingdom (ELSA), and the United States (HRS).

This study utilized data from three prospective cohort studies: the China Health and Retirement Longitudinal Study (CHARLS), the English Longitudinal Study of Ageing (ELSA), and the Health and Retirement Study (HRS). Frailty status was assessed using the Rockwood frailty index and categorized into robust, pre-frail, and frail. Pain was evaluated by self-reports. Pain degrees were categorized into mild, moderate and severe. Pain areas were grouped into four main areas: head and neck, trunk, limbs, oral. Generalized linear mixed-effects models were employed to analyze the longitudinal relationship between frailty and pain while adjusting for covariates, including gender, age, marital status, education level, sleep quality, smoking, drinking, hypertension, and diabetes.

According to the inclusion and exclusion criteria, 10,624 participants from CHARLS (47% female, mean age: 60.76 years), 4,945 participants from ELSA (52.2% female, mean age: 70.05 years), and 11,439 participants from HRS (55.8% female, mean age: 69.28 years) were included in the subsequent analysis. Compared to robust individuals, those in pre-frail and frail states showed a significantly increased risk of experiencing pain. In all three cohorts, pre-frail individuals had a 3.82-fold increased likelihood of pain compared to robust individuals (OR = 3.82, 95%CI = 3.51–4.15, p-value<0.001, CHARLS), 4.29-fold (OR = 4.29, 95%CI = 3.74–4.93, p-value<0.001, ELSA), and 4.17-fold (OR = 4.17, 95%CI = 3.81–4.57 p-value<0.001, HRS). Frail individuals had a 10.44-fold increased likelihood of pain (OR = 10.44, 95%CI = 9.05–12.04, p-value<0.001, CHARLS), 10.14-fold (OR = 10.14, 95%CI = 8.05–12.76, p-value<0.001, ELSA), and 13.27-fold (OR = 13.27, 95%CI = 11.71–15.03, p-value<0.001, HRS).

This study demonstrates that frailty significantly impacts the risk of pain, the degree of pain, and the areas of pain. And this association is consistently observed across older populations in different countries. Future pain management strategies should incorporate frailty assessments to mitigate the adverse effects of pain on the health of older adults.