Study design: Clinicoepidemiologic study in the Chianti area (Tuscany, Italy).
Objective: To evaluate whether performance measures of lower extremity function confounds the association of low back pain (LBP) with self-report disability in specific basic and instrumental activities of daily living (IADLs).
Summary of background data: LBP is high prevalent in older population and has a negative impact on functional status. Studies on the pathway leading from LBP to disability are limited and often the role played by important confounders is not considered.
Methods: A total of 956 InCHIANTI study participants aged 65 and older able to complete performance-based tests of lower extremity function were included in this analysis. LBP was defined as a self-report of back pain "quite often-almost every day" in the past 12 months. Lower extremity function was evaluated administering the Short Physical Performance Battery. In addition, participants were asked to walk on a 7-m course and collect an object from the ground. Depressive symptoms (CES-D score), trunk flexion-extension range of motion, and hip-knee-foot pain were also considered in the pathway from LBP to disability.
Results: Compared with participants who did not report LBP, those with LBP were more likely to report difficulty in performing most activities of daily living. LBP was also associated with disability in the activities of bathing, doing the laundry, performing heavy household chores, cutting toenails, shopping, and carrying a shopping bag. The association between LBP and disability in selected ADLs and IADLs was no longer statistical significant, after adjustment for performance in lower extremity function, with exception of the activity of "carrying a shopping bag".
Conclusion: The cross-sectional association between LBP and self-reported disability, in specific tasks is modulated by performance measures. Specific performance-based tests that explore the functional consequences of LBP may help design specific interventions of disability prevention and treatment in patients with LBP.