Background/Purpose: Although back pain is common and costly, few longitudinal studies have evaluated the association between back pain, severe enough to restrict activity (hereafter referred to as restricting back pain), and the development of disability in mobility. Older persons who lose independent mobility have higher rates of morbidity and mortality, and experience a poorer quality of life. The objective of this study is to evaluate restricting back pain and subsequent mobility disability, both dynamic conditions that recur in older persons.

Methods: We evaluated the 709 participants (mean age 77.3 years, range 70-96, 63% women) of the Precipitating Events Project, a prospective study of community-living persons, aged 70+ years, all non-disabled at baseline, who completed monthly telephone assessments of restricting back pain and who were at risk for developing mobility disability for up to 159 months. Restricting back pain was defined as staying in bed for at least half a day and/or cutting down on one’s usual activities due to back pain. Mobility disability was defined as needing help with or inability to complete any of the following three tasks in any given month: walking a 1/4 mile, climbing a flight of stairs, lifting or carrying 10 pounds. The event rate for mobility disability was estimated using a GEE Poisson model. A recurrent events Cox model was used to evaluate the associations between the occurrence of restricting back pain (yes/no) and subsequent (within one month) mobility disability. The model was adjusted for fixed-in-time (sex, education, ethnicity) and time-varying covariates (age, chronic conditions, BMI, depressive symptoms, cognitive impairment, hip weakness, and physical frailty defined by slow gait speed) that were updated every 18 months. In a secondary analysis, these models were re-run after excluding participants who had mobility disability at baseline. We ran a final set of analyses, focusing on the relationship between restricting back pain and mobility disability that persisted for at least two months.

Results: The event rate for mobility disability was 7.26 per 100-person months (95% CI 6.89,7.64) with a median duration of 2 (interquartile range: 1-4) months. Overall, 213 (30%) of the 709 eligible participants reported one or more of the three disabilities at baseline and recovered at some point during the follow-up. The frequency of each of the three mobility disability items at baseline was 20.2% for walking a 1/4 mile, 6.6% for climbing stairs, and 19% for lifting/carrying 10 pounds. After adjusting for covariates, restricting back pain was strongly associated with subsequent mobility disability, with a hazard ratio (HR) (95% CI) of 3.23 (2.87,3.64) in the primary analytic sample, HR 3.71 (3.22,4.27) after omitting subjects with baseline mobility disability, and HR 3.64 (3.15,4.20) in the analyses evaluating longer duration of mobility disability.

Conclusion: In this longitudinal study, restricting back pain was independently associated with subsequent mobility disability among older persons. Interventions implemented to decrease or prevent restricting back pain may reduce the likelihood of mobility disability.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/restricting-back-pain-and-subsequent-mobility-disability-in-community-living-older-persons/