Functional Status Score for the ICU: An International Clinimetric Analysis of Validity, Responsiveness, and Minimal Important Difference.

OBJECTIVES: To evaluate the internal consistency, validity, responsiveness, and minimal important difference of the Functional Status Score for the ICU, a physical function measure designed for the ICU. DESIGN: Clinimetric analysis. SETTINGS: Five international datasets from the United States, Australia, and Brazil. PATIENTS: Eight hundred nineteen ICU patients. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: Clinimetric analyses were initially conducted separately for each data source and time point to examine generalizability of findings, with pooled analyses performed thereafter to increase power of analyses. The Functional Status Score for the ICU demonstrated good to excellent internal consistency. There was good convergent and discriminant validity, with significant and positive correlations (r = 0.30-0.95) between Functional Status Score for the ICU and other physical function measures, and generally weaker correlations with nonphysical measures (|r| = 0.01-0.70). Known group validity was demonstrated by significantly higher Functional Status Score for the ICU scores among patients without ICU-acquired weakness (Medical Research Council sum score, ≥ 48 vs < 48) and with hospital discharge to home (vs healthcare facility). Functional Status Score for the ICU at ICU discharge predicted post-ICU hospital length of stay and discharge location. Responsiveness was supported via increased Functional Status Score for the ICU scores with improvements in muscle strength. Distribution-based methods indicated a minimal important difference of 2.0-5.0. CONCLUSIONS: The Functional Status Score for the ICU has good internal consistency and is a valid and responsive measure of physical function for ICU patients. The estimated minimal important difference can be used in sample size calculations and in interpreting studies comparing the physical function of groups of ICU patients.

Association between physical activity measurements and key parameters of cardiopulmonary exercise testing in patients with heart failure.

BACKGROUND: A hallmark characteristic of heart failure (HF) is reduced physical activity (PA) patterns. The relationship between key cardiopulmonary exercise testing (CPX) variables and PA patterns has not been investigated. Therefore, we evaluated PA patterns in patients with ischemic HF and its relationship to peak oxygen consumption (VO2), the minute ventilation/carbon dioxide production (VE/VCO2) slope, and the oxygen uptake efficiency slope (OUES). METHODS AND RESULTS: Sixteen patients with HF wore an accelerometer for six days to measure total steps/day as well as percentage of time at light, moderate, and vigorous PA. Symptom-limited CPX was performed on a treadmill using a ramping protocol. Total steps correlated with VO2 (r = 0.64 P < .05), the VE/VCO2 slope (r = -0.72; P < .05), and the OUES (0.63; P < .05). The percentage of time at light-intensity PA correlated with the VE/VCO2 slope (r = 0.58; P < .05) and the OUES (r = -0.51; P < .05). The percentage of time at vigorous-intensity PA correlated with peak VO2 (r = 0.55; P < .05) and the VE/VCO2 slope (r = -0.52; P < .05). CONCLUSIONS: PA assessed by accelerometer is significantly associated with key CPX variables in patients with HF.