Physical function and activity of patients after open abdominal surgery: a prospective cohort study comparing the clinimetric properties of two outcome measures.

ABSTRACT

OBJECTIVES: To measure and compare the clinimetric properties of the Chelsea Critical Care Physical Assessment (CPAx) and Physical Function in Intensive Care Test-scored (PFIT-s) for assessment of physical function and activity. DESIGN: Prospective cohort design using crossover-randomisation of the sequence in which participants were assessed with CPAx and PFIT-s. SETTING: Surgical and transplant intensive care units (ICU) in an academic hospital. PARTICIPANTS: Adults who underwent elective open abdominal surgery. Consecutive sampling was used to enrol 69 participants. INTERVENTIONS: Physical function and activity were assessed on ICU days one, three, five and at ICU discharge using the CPAx and PFIT-s in random order. MAIN OUTCOME MEASURES: Responsiveness to change, minimal clinically important difference (MCID), floor and ceiling effect, and convergent validity. RESULTS: CPAx demonstrated a large responsiveness (effect size index (ESI)= 0.83) and PFIT-s moderate responsiveness (ESI=0.73) to change in scores. MCID for CPAx was 2.1 (standard error of measurement (SEM) 1.1) and for PFIT-s 0.6 (SEM=0.3). CPAx had no floor effect and a small ceiling effect (9%, n = 6) at ICU discharge compared to 2% (n = 1) floor and 48% (n = 32) ceiling effects of PFIT-s. Moderate convergent validity was found for both tools at ICU admission (n = 67, r = 0.62, p < 0.001) and discharge (n = 67, r = 0.51, p < 0.001). CONCLUSION: CPAx is most responsive to changes in physical function and activity scores, has no floor and limited ceiling effects and moderate convergent validity, and is recommended for similar cohorts. CONTRIBUTION OF THE PAPER.