A global measure of physical functioning: psychometric properties.

Area of Science:

• Medical assessment
• Health outcomes research
• Psychometrics

Background:

• Physical functioning is a critical aspect of patient recovery and quality of life after surgery.
• Existing measures may not adequately capture the full spectrum of physical function.
• A reliable and valid self-report scale is needed to assess global physical functioning.

Purpose of the Study:

• To evaluate the psychometric properties of the Global Physical Functioning Scale (GPFS).
• To establish the reliability, validity, and sensitivity to change of the GPFS as a self-report measure.
• To determine the scale's suitability for outcome studies in surgical populations.

Main Methods:

• Collected self-ratings from surgical patients and clinician ratings between 1997 and 1999.
• Assessed test-retest reliability, patient-clinician score convergence, and inter-rater reliability.
• Examined discriminative validity, sensitivity to change, and ceiling/floor effects in various surgical patient groups.
• Compared GPFS scores with the SF-36 physical functioning scale (PF-10) for concurrent validity.

Main Results:

• High test-retest reliability (r=.90), patient-clinician correlation (r=.87), and inter-rater reliability (ICC=.82).
• The GPFS effectively discriminated between different physical functioning levels and showed sensitivity to change post-coronary surgery.
• Moderate ceiling effects were observed, but no floor effects. Concurrent validity with SF-36 PF-10 was .67.
• GPFS demonstrated superior differentiation of middle physical functioning levels compared to PF-10.

Conclusions:

• The Global Physical Functioning Scale (GPFS) exhibits adequate psychometric properties for measuring general physical functioning.
• The scale is user-friendly and suitable for outcome studies, particularly those involving significant changes in physical function, such as after coronary surgery.