THE RELATIONSHIP BETWEEN SELF-REPORT AND PERFORMANCE-BASED MEASURES OF PHYSICAL FUNCTION FOLLOWING AN INTENSIVE CARE UNIT STAY

Abstract

PURPOSE: The relationship between self-report and performance-based measures of physical function has not been addressed in ICU patients. The purpose of this study was to examine this association in these patients. METHODS: 300 ICU patients were randomized into an exercise program (ExP) or standard of care (SoC). Self-report (SF-36 Physical Function Subscale (SF-36pfs), Functional Performance Inventory-Short Form (FPI-SF)) as well as performance-based (Short Physical Performance Battery (SPPB), skeletal muscle strength) measures were taken at hospital discharge, 2, 4, and 6 months post-enrollment. Partial correlations between self-report and performance-based measures of physical function in each group were calculated. Covariates included age, APACHE III score, and gender. Alpha was set at p < 0.05. RESULTS: At hospital discharge, a significant, but weak, correlation (r = 0.32) was found between the SF-36 and SPPB in the SoC group. At 2 months, weak to moderate correlations were found between self-report and performance measures in both groups. In the SoC group, the SF-36 was significantly correlated with the SPPB (r = 0.47) and muscular strength (r = 0.34); the FPI was significantly correlated with the SPPB (r = 0.64) and muscular strength (r = 0.52. In the ExP group, the SF-36 was significantly correlated with the SPPB (r = 0.61) and muscular strength (r = 0.42); the FPI was significantly correlated with the SPPB (r = 0.54) and with muscular strength (r = 0.28). A similar pattern was seen at 4 and 6 months in both groups. CONCLUSION: Self-report and performance-based measures of physical function appear to assess different constructs at hospital discharge. Following recovery from an ICU stay, these measures become complementary, but indicate different constructs are being assessed.