In summary, older Chinese individuals with chronic musculoskeletal pain have a lower HRQoL compared to the general population in Hong Kong. This is evident from the distinct EQ-5D index score of 0.70, in contrast to the higher score of 0.92 observed in the general population.20 When considering the biopsychosocial framework of chronic pain, physical factors such as pain intensity and knee pain, and psychological factors like depression and anxiety, were significantly associated with lower HRQoL.
We further investigated the impact of pain intensity, knee pain, depression, and anxiety on different dimensions of EQ-5D. Our findings revealed that individuals with higher BPI severity scores were more likely to report "having problems" in four out of five EQ-5D dimensions, namely "mobility," "self-care," "usual activities," and "pain/discomfort." Interestingly, our study did not find a significant association between pain intensity and the "anxiety/depression". This aligns with a previous study conducted by Björn Gerdle et al., which suggested that although anxiety and depression symptoms often accompany chronic pain, the correlation between pain intensity and psychological distress levels is relatively weak.21 This complexity can be attributed to the intricate relationship between pain intensity and psychological distress, which can be influenced by individual coping strategies, attention, cognition, and emotion regulation.22 23
Compared to other musculoskeletal regions, older individuals who reported knee pain as their most severe pain region showed a significant association with reduced HRQoL. This aligns with previous studies which showed that knee pain was significantly associated with lower HRQoL in older populations. 24 25 It is worth noting that knee pain was only found to be associated with the "mobility" and "usual activity" dimensions of EQ-5D. This was consistent with previous study which found that mobility limitation reduces HRQoL.26 Therefore, we suggest that when developing treatment strategies for knee pain in older individuals, interventions and resources should prioritize to enhance mobility and ability to perform usual activities, thus potentially improve their overall HRQoL.
Depression and anxiety are well-known to be associated with reduced HRQoL among patients with chronic pain.27 28 In terms of their influence on the individual dimensions of EQ-5D, the PHQ-9 was found to be significantly associated with "mobility," "self-care," "usual activities," and "anxiety/depression." On the other hand, the GAD-7 was only associated with the "anxiety/depression" dimension. Again, we did not find any association between psychological distress and the "pain/discomfort" dimension. These findings hold important clinical implications. When encountering chronic pain patients with depression, it is essential to not only manage the depressive symptoms but also focus on enhancing their physical functioning and self-management skills in order to improve their overall HRQoL. On the other hand, for those with comorbid anxiety, treatment can be specifically targeted at dealing with anxiety in order to improve their overall HRQoL.
To the best of our knowledge, this is the first study to evaluate the individual contributions of physical, psychological, and social factors on HRQoL within a single cohort of older individuals with chronic musculoskeletal pain. There were few limitations. First, the study recruitment was limited to community-dwelling older individuals, which may restrict the generalizability of the findings to those with limited mobility or residing in nursing homes. Second, factors such as cognitive function and the use of chronic medications were not included in this analysis. Third, the social factors collected in this study were not comprehensive to cover all aspects of individuals social background. Finally, there was a possibility of self-selection bias, although efforts were made to ensure that the sample was representative of the Hong Kong population aged 60 or above.
Our findings have several clinical implications. Firstly, we identified key determinants of HRQoL within the biopsychosocial framework of chronic pain, emphasizing the need to address pain intensity, knee pain, depression, and anxiety as priorities for resource allocation. Secondly, our evaluation of individual determinants on the five dimensions of EQ-5D informs the development of targeted treatment strategies to enhance overall HRQoL. For instance, reducing pain intensity should focus on improving mobility, self-care, and the ability to perform usual activities. Interventions targeting knee pain should prioritize improvements in mobility and self-care. Patients with comorbid depression and chronic pain would benefit from multidisciplinary care, while individuals with comorbid anxiety may benefit from targeted treatment addressing their anxiety symptoms.