Highlights
- •The newly developed regional lower extremity physical function (LEPF) patient-reported outcome measure (PROM) is reliable, valid, and efficient.
- •The LEPF computerized adaptive test and LEPF short form can be used for research and clinical care.
- •Clinicians may simplify PROM administration by using a single regional measure.
Abstract
Objective
To calibrate the Lower Extremity Functional Scale (LEFS) items into a regional lower
extremity physical function (LEPF) item bank and assess reliability, validity, and
efficiency of computerized adaptive test (CAT) and short form (SF) administration
modes.
Design
Retrospective cohort.
Setting
Data were collected from patients treated in outpatient rehabilitation clinics for
musculoskeletal impairments of the hip, knee, foot, and ankle that responded to all
20 LEFS items at intake.
Participants
Patients aged 14 years or older who started an episode of care during January 2016-October
2019 and identified the lower extremity region as the source of a primary musculoskeletal
complaint. Total cohort included 78,186 patients (mean age, 53±19y, range, 14-89y).
Interventions
Not applicable.
Main Outcome Measures
Item response theory (IRT) model assumptions of unidimensionality, local item independence,
item fit, and presence of differential item functioning (DIF) were studied. LEPF-CAT–
and LEPF-SF–generated scores were evaluated.
Results
An 18-item solution was supported for its unidimensionality and fit to the IRT model,
with reliability estimates >0.9 for all administration modes. No DIF impact on LEPF
scores was identified. Scores discriminated between multiple patient groups in clinically
logical ways and were highly responsive to change, with negligible floor or ceiling
effects. CAT scores were generated using an average of 4.9 items (median, 4).
Conclusions
The LEPF scores were reliable, valid, and efficient for assessing perceived physical
function of patients with musculoskeletal impairments of the hip, knee, foot, and
ankle; thus, it was found suitable for research and routine clinical administration.
These findings are limited to the type of patients included in this study, with further
validation needed to assess their generalizability.
Keywords
List of abbreviations:
CAT (computerized adaptive test), CBFA (confirmatory bifactor analysis), CFA (confirmatory factor analysis), CFI (comparative fit index), DIF (differential item functioning), ECV (explained common variance), EFA (exploratory factor analysis), FOTO (Focus on Therapeutic Outcomes), IRT (item response theory), LEFS (Lower Extremity Functional Scale), LEPF (lower extremity physical function), omega-H (omega-hierarchical), PROM (patient-reported outcome measure), RMSEA (root mean square error of approximation), SF (short form), SRMR (standardized root mean square residual), TLI (Tucker-Lewis index)To read this article in full you will need to make a payment
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Article info
Publication history
Published online: March 04, 2021
Accepted:
February 6,
2021
Received in revised form:
January 8,
2021
Received:
December 16,
2020
Footnotes
Disclosures: Drs Cook, Tucker, and Kallen acknowledge that they are consultants for Net Health Systems, Inc, the company that owns the Focus on Therapeutic Outcomes (FOTO) patient outcomes system that gathers and manages the data analyzed in this manuscript. The authors certify that they have no other affiliations with or financial involvement in any organization or entity with a direct financial interest or any competing interests in the subject matter or materials discussed in the article.
Identification
Copyright
© 2021 The American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.
