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. We hypothesized that restricting back pain would be strongly associated with mobility disability over the 13+ years of follow-up.

Methods: We evaluated the 555 participants (mean age 77.5 years, 56% 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 (hereafter referred to as disability) was defined as needing help with or inability to complete any of the following four tasks in any given month: walking a 1/4 mile, climbing a flight of stairs, lifting or carrying 10 pounds, or driving a car. The event rate for disability was estimated using a Generalized Estimation Equation 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) disability. The model was adjusted for fixed-in-time (sex, education, ethnicity) and time-varying covariates (age, chronic conditions, BMI, depressive symptoms, cognitive impairment, and physical frailty defined by slow gait speed) that were updated every 18 months. We tested potential interactions of restricting back pain with sex, BMI, depressive symptoms, and physical frailty.

Results: The event rate for disability was 8.47 per 100-person months (95% CI 8.08,8.88) with a median duration of 2 (interquartile range: 1-5) months. The frequency of each of the four disability items at baseline was 13.2% for walking a 1/4 mile, 3.6% for climbing stairs, 10.5% for lifting/carrying 10 pounds, and 11.2% for driving a car. After adjusting for covariates, restricting back pain was strongly associated with subsequent disability, with a hazard ratio (95% CI, p-value) of 3.35 (2.91,3.86, <0.001). Only the interaction with physical frailty was statistically significant (p = <0.001). Subgroup analyses suggest that restricting back pain is associated with disability among participants with and without physical frailty at baseline assessment 2.10 (1.67,2.63) and 4.06 (3.42,4.81), respectively.

Conclusion: In this longitudinal study, restricting back pain was independently associated with disability among older persons. It is possible that individuals who are not physically frail may be more active and therefore at higher risk for developing subsequent disability. Calculating absolute risk differences may help to clarify the results of our subgroup analysis. Interventions implemented to decrease or prevent restricting back pain are likely to decrease disability.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/restricting-back-pain-is-associated-with-disability-in-community-living-older-persons/