title: Lower limb functional index: development and clinimetric properties.
abstract: BACKGROUND
  Existing lower-limb, region-specific, patient-reported outcome measures have clinimetric limitations, including limitations in psychometric characteristics (eg, lack of internal consistency, lack of responsiveness, measurement error) and the lack of reported practical and general characteristics. A new patient-reported outcome measure, the Lower Limb Functional Index (LLFI), was developed to address these limitations.
  
  
  OBJECTIVE
  The purpose of this study was to overcome recognized deficiencies in existing lower-limb, region-specific, patient-reported outcome measures through: (1) development of a new lower-extremity outcome scale (ie, the LLFI) and (2) evaluation of the clinimetric properties of the LLFI using the Lower Extremity Functional Scale (LEFS) as a criterion measure.
  
  
  METHODS
  This was a prospective observational study.
  
  
  METHODS
  The LLFI was developed in a 3-stage process of: (1) item generation, (2) item reduction with an expert panel, and (3) pilot field testing (n=18) for reliability, responsiveness, and sample size requirements for a larger study. The main study used a convenience sample (n=127) from 10 physical therapy clinics. Participants completed the LLFI and LEFS every 2 weeks for 6 weeks and then every 4 weeks until discharge. Data were used to assess the psychometric, practical, and general characteristics of the LLFI and the LEFS. The characteristics also were evaluated for overall performance using the Measurement of Outcome Measures and Bot clinimetric assessment scales.
  
  
  RESULTS
  The LLFI and LEFS demonstrated a single-factor structure, comparable reliability (intraclass correlation coefficient [2,1]=.97), scale width, and high criterion validity (Pearson r=.88, with 95% confidence interval [CI]). Clinimetric performance was higher for the LLFI compared with the LEFS on the Measurement of Outcome Measures scale (96% and 95%, respectively) and the Bot scale (100% and 83%, respectively). The LLFI, compared with the LEFS, had improved responsiveness (standardized response mean=1.75 and 1.64, respectively), minimal detectable change with 90% CI (6.6% and 8.1%, respectively), and internal consistency (α=.91 and .95, respectively), as well as readability with reduced user error and completion and scoring times.
  
  
  CONCLUSIONS
  Limitations of the study were that only participants recruited from outpatient physical therapy clinics were included and that no specific conditions or diagnostic subgroups were investigated.
  
  
  CONCLUSIONS
  The LLFI demonstrated sound clinimetric properties. There was lower response error, efficient completion and scoring, and improved responsiveness and overall performance compared with the LEFS. The LLFI is suitable for assessment of lower-limb function.
authors: Faculty of Science, Health and Education, Centre for Healthy Activities, Sport and Exercise, University of the Sunshine Coast, PO Box 760, Coolum Beach, Queensland, Australia 4573. cp.gabel@bigpond.com
authors: Charles Philip
authors: CP
authors: Gabel
authors: Markus
authors: M
authors: Melloh
authors: Brendan
authors: B
authors: Burkett
authors: Lori A
authors: LA
authors: Michener
mesh_terms: D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007866:Leg / Q000503:physiopathology*; D008297:Male; D017063:Outcome Assessment, Health Care; D010147:Pain Measurement; D011446:Prospective Studies; D011594:Psychometrics; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires