Objectives: To describe the relationship between symptom scores and mobility function measures, assess whether symptom scores and disease scores are similarly associated with mobility function, and identify clusters of symptoms that are most strongly associated with functional status in older adults.
Design: Secondary analysis of cross-sectional data from three cohorts.
Setting: Academic medical center.
Participants: One hundred ninety-five community-dwelling subjects with poor flexibility or cardiorespiratory fitness (fitness cohort), 211 female retirement community residents with vertebral fractures (VF cohort), and 61 subjects with Parkinson's disease (PD cohort).
Measurements: Twenty-item self-reported symptom scale, 17-item self-reported disease scale, Medical Outcomes Study 36-item Short Form Survey (SF-36) Physical Functioning Scale, 5-item Nagi Disability scale, 10-m walk time, supine to stand time.
Results: Symptom scores correlated with mobility function measures (Spearman correlation coefficients ranged from 0.222 to 0.509) at least as strongly as, if not more strongly than, did disease scores. Symptom scores remained associated with functional outcomes after controlling for disease score and demographic variables. Adding symptom scores to models that contained disease scores significantly increased the association with functional outcomes. In the fitness cohort, muscle weakness was the most explanatory single symptom, associated with an average decrease of 17.8 points on the Physical Functioning Scale. A model that included only muscle weakness, pain, and shortness of breath accounted for 21.2% of the variability in the Physical Functioning Score.
Conclusion: Symptoms represent useful indicators of disability burden in older adults and are promising targets for interventions to improve function in medically complex patients.