Clinical interpretation of outcome measures generated from a lumbar computerized adaptive test

Area of Science:

• Rehabilitation Medicine
• Biostatistics
• Health Outcomes Research

Background:

• Computerized adaptive testing (CAT) is an efficient method for estimating functional status (FS) in individuals with impairments.
• The Back Pain Functional Scale (BPFS) is a common tool for assessing back pain-related functional limitations.

Purpose of the Study:

• To interpret functional status (FS) estimated by a lumbar CAT developed using BPFS items and physical functioning items.
• To establish meaningful interpretations for FS scores derived from a CAT in patients with lumbar impairments.

Main Methods:

• A prospective longitudinal cohort study involved 17,439 patients with lumbar impairments across 377 outpatient clinics.
• Functional status (FS) was assessed using a lumbar CAT (0-100 scale).
• Data interpretation involved calculating confidence intervals, percentile ranks, minimal detectable change (MDC), clinically important change, and applying a functional staging model (BPFCS).

Main Results:

• The average precision of a single FS score was +/-4.
• Percentile ranks indicated improvements in FS scores from intake to discharge.
• An MDC(95) of 8+ indicated statistically reliable change, and a 5+ point change suggested minimal clinically important improvement.
• The developed Back Pain Function Classification System (BPFCS) provided clinical insights.

Conclusions:

• The BPFCS requires further validity assessment through prospective studies.
• These findings can enhance the clinical interpretation of CAT-generated outcome measures.
• The results support clinicians in utilizing patient-reported outcomes in physical therapist practice.