Patients with worse mental health report more physical limitations after adjustment for physical performance.

OBJECTIVE: To determine whether mental health scores are associated with self-reported physical limitations after adjustment for physical performance. Patient-reported physical limitations are widely used to assess health status or the impact of disease. However, patients' mental health may influence their reports of their physical limitations.
METHODS: Mental health and physical limitations were measured using the SF-36v2 mental health and physical functioning subscales in a cross-sectional study of 1024 participants. Physical performance was measured using tests of strength, endurance, dexterity, and flexibility. Multivariable linear regression was performed to examine the relationship between self-reported mental health and physical limitations adjusting for age, gender, race/ethnicity, education, body mass index, and measured physical performance.
RESULTS: The score distributions for mental health and physical functioning were similar to that of the United States population in this age range. In unadjusted analyses, every 10-point decline in mental health scores was associated with a 4.8-point decline in physical functioning scores (95% Confidence Interval (CI) = -4.2 to -5.3; p < .001). After adjusting for covariables including measured physical performance, every 10-point decline in mental health scores was associated with a 3.0-point decline in physical functioning scores (95% CI = -2.5 to -3.6; p < .001).
CONCLUSIONS: People with poor mental health scores seem to report more physical limitations than would be expected based on physical performance. When comparing self-reported physical limitations between groups, it is important to consider differences in mental health.