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In this cohort of ∼900 community-dwelling older adults without dementia, stroke, or Parkinson's disease, the risk of developing incident IADL, ADL, and mobility disability increased as more areas with musculoskeletal pain were reported. These associations did not vary by age, sex, or education, and they remained significant after controlling for several possible confounders including BMI, physical activity, cognition, depressive symptoms, vascular risk factors, and vascular diseases. These results extend the prior literature and suggest that musculoskeletal pain may be a modifiable risk factor for decreasing the burden of disability in community-dwelling older adults. Further, they suggest that the number of musculoskeletal areas affected by pain may have prognostic significance.
There has been an increased awareness and understanding of the growing burden of musculoskeletal conditions both in the elderly and to society. Studies that have focused on pain in a particular body area, such as low back pain or lower extremity pain, report that both are associated with a subsequent decline in physical performance (20–22). There have been few longitudinal studies that have examined the contribution of musculoskeletal pain to the development of disability in community-dwelling older adults (23). A recent longitudinal study reported that the number of locations and severity of chronic musculoskeletal pain is associated with risks of falling (24). Pain in multiple areas has been reported to be associated with an increased risk of progression from mild to severe ADL disability and mobility disability in women (3, 25). The current study extends these prior studies by showing that more widespread musculoskeletal pain is associated with an increased risk of developing both IADL and Katz disability. Although the association of musculoskeletal pain and the development of self-reported mobility disability showed a trend for significance, the effect size for this association was similar to the association obtained in a model for incident performance-based mobility disability corroborating this association. A similar percentage of participants with 1 or 2 areas of pain and 3 or more areas of pain subsequently developed IADL and mobility disability (Table 3). Further work is needed to examine whether there may be a threshold effect for pain and the subsequent development of different disabilities.
The current study suggests that the presence of musculoskeletal pain may be an important clinical marker for identifying older adults at increased risk for developing a wide range of disabilities. The results of the current study have important translational implications since they suggest that the public health efforts to encourage lifestyle changes and interventions that would ameliorate pain might increase the efficacy of efforts to decrease the burden of disabilities in our rapidly aging population.
Musculoskeletal conditions vary with regard to their pathophysiology, but they are linked anatomically through the structural changes in the bones, joints, and muscles, leading to long term pain and disability in adults. The basis for the association between musculoskeletal pain and disability is uncertain but is likely multifactorial. Prior studies have shown that radiologic or physical joint changes are not as robustly associated with disability as reports of pain, suggesting that other factors are involved in the association (26). While disability due to musculoskeletal pain is often ascribed to osteoarthritis in a specific joint (e.g., the knee), recent work suggests that pain is multifaceted and complex (27–29). For example, the pain matrix in joint or spine disease constitutes an interaction between structural pathology, neural innervation of the joint (sensory, motor, autonomic), dysfunction of pain processing at spinal and cortical levels, and various environmental and individual determinants (i.e., affective, cognitive). Therefore, pain reflects the integrated result of multiple biologic and psychosocial inputs that are not fully understood (28, 29). Our finding that musculoskeletal pain was associated with the development of a wide range of disabilities suggests that pain may affect changes in the central nervous system pathways that mediate both motor and nonmotor functions. Further work is needed to explicate the biology of the link between pain and disability.
The current study has several limitations. The selected nature of the cohort, which included participants willing to provide organ donation and the low prevalence of musculoskeletal pain, underscores the need for replication of these results in a population-based study. Although the current study provides important longitudinal data about pain and incident disability, it is an observational study so causal inferences are limited. Therefore we cannot determine whether musculoskeletal pain causes disability or whether both share a common underlying pathophysiology. Pain is a multidimensional construct, and the current study assessed the number of areas with musculoskeletal pain during a 1-month period. Further studies are needed to examine the contributions of other dimensions of pain including chronicity, frequency, and severity. Finally, we did not have objective-measures physical examination, radiologic, or pathology findings that would provide more precise characterization and classification of the causes of pain.
Our study is strengthened by having a large cohort in which simultaneous measures of musculoskeletal pain and disability were obtained, by the longitudinal design, and by our ability to control for important covariates, especially detailed cognitive function. Our use of a community-based sample rather than a clinic-based sample reduces one type of selection bias. Further, we excluded persons with common neurologic conditions that cause disability, and we considered several covariates that may affect the relationship of musculoskeletal pain and mobility disability. This study suggests that in ambulatory community-dwelling older adults without disability, the number of regions affected with musculoskeletal pain is related to the subsequent risk of developing disability. Public health programs to encourage lifestyle changes and ameliorate musculoskeletal pain might decrease the burden of disability in our aging population.
- Top of page
- SUBJECTS AND METHODS
- AUTHOR CONTRIBUTIONS
All authors were involved in drafting the article or revising it critically for important intellectual content, and all authors approved the final version to be submitted for publication. Dr. Buchman had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study conception and design. Buchman, Shah, Leurgans, Boyle, Wilson, Bennett.
Acquisition of data. Buchman, Shah, Wilson, Bennett.
Analysis and interpretation of data. Buchman, Shah, Leurgans, Boyle, Wilson.