The Upper Limb Functional Index: development and determination of reliability, validity, and responsiveness
C Philip Gabel1, Lori A Michener, Brendan Burkett
1Virginia Commonwealth University, Medical College of Virginia, Richmond, USA. cp.gabel@bigpond.com
Purpose:
Current upper limb regional self-report outcome measures are criticized for poor clinical utility, including length, ease, and time to complete and score, missing responses, and poor psychometric properties. To address these concerns a new measure, the Upper Limb Functional Index (ULFI), was developed with reliability, validity, and responsiveness being determined in a prospective study.
Methods:
Patients from nine Australian outpatient settings completed the ULFI and two established scales, the Disabilities of the Arm, Shoulder, and Hand (DASH) (n=214) and the Upper Extremity Functional Scale (UEFS) (n=64) concurrently to enable construct and criterion validity to be assessed. Two subgroups were used to assess test-retest reliability at 48-hour intervals (n=46) and responsiveness through distribution-based methods (n=29). Internal consistency, change scores, and missing responses were calculated. Practical characteristics of the scale were assessed.
Results:
The ULFI correlated with the DASH (r=0.85; 95% CI) and UEFS (r=0.78; 95% confidence interval [CI]), demonstrated test-retest reliability (intraclass correlation coefficient=0.96; 95% CI) and internal consistency (Cronbach alpha=0.89). The change scores of the ULFI with standard error of the measurement was 4.5% or 1.13 ULFI-points and minimal detectable change at the 90% CI was 10.4% or 2.6 ULFI-points. Responsiveness indices were standardized response mean at 1.87 and effect size at 1.28. The ULFI demonstrated an impairment range of 0-100%, with no missing responses and a combined patient completion and therapist scoring time of less than 3 minutes.
Conclusions:
The ULFI demonstrated sound psychometric properties, practical characteristics, and clinical utility thereby making it a viable clinical outcome tool for the determination of upper limb status and impairment. The ULFI is suggested as the preferred upper limb regional tool due to its superior practical characteristics and clinical utility, and comparable psychometric properties without a tendency toward item redundancy.
