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 (RBP)] and the development of disability. The objective of this study is to evaluate the association between RBP and subsequent episodes of disability in basic, instrumental, and mobility activities, respectively.

Methods: Participants included the 754 members of the Precipitating Events Project (median age 78 y, 64.6% women), a prospective study of community-living persons, aged 70+ years, who completed monthly telephone assessments of RBP and disability, and who were at risk for developing new and recurrent disability episode(s) for up to 159 months. RBP was defined as staying in bed for at least 1/2 day and/or cutting down on one’s usual activities due to back pain. Disability was defined as needing help with/inability to complete ³1 of the activities, listed in the Table, in any given month for each of the three outcome categories. The event rates for the three disability outcomes were estimated using a GEE Poisson model. A recurrent events Cox model was used to evaluate the association between RBP and each of the three disability outcomes. The model was adjusted for fixed-in-time (sex, education, ethnicity) and time-varying covariates (listed in Table) (age, chronic conditions, BMI, depressive symptoms, cognitive impairment, physical frailty) that were updated every 18 months.

Results: For the basic, instrumental and mobility activities, the disability event rates were: 3.6 per 100-person months (95% CI 3.37, 3.89), 8.5 per 100-person months (95% CI 8.05, 8.98), and 9.38 per 100-person months (95% CI 8.98,9.81), respectively, with a median duration of 2 months per disability episode for each of the three outcomes. The unadjusted and adjusted associations of restricting back pain with the 3 disability outcomes are listed in the Table.

Conclusion: In this longitudinal study, RBP was independently associated with disability in basic, instrumental and mobility activities among older persons. Interventions directed at preventing or decreasing RBP may reduce the likelihood of disability in activities across three key domains of function.