Minimal clinically important difference of the L Test for individuals with lower limb amputation: A pilot study

Prosthet Orthot Int. 2015 Dec;39(6):470-6. doi: 10.1177/0309364614545418. Epub 2014 Aug 18.


Background: The L Test is a reliable/valid clinical evaluation of mobility that measures walking speed in seconds. It can be used with individuals with lower limb amputation. Responsiveness of the L Test is not yet determined.

Objectives: The purpose of this pilot study was to determine how well the L Test identified individuals with a lower limb amputation who have/have not undergone a minimal clinically important difference.

Study design: Prospective follow-up study.

Methods: In total, 33 individuals with lower limb amputation, deemed to require a major intervention, were recruited consecutively from a follow-up clinic. Participants completed the L Test at baseline and follow-up. A Global Rating Change scale was also completed at follow-up.

Results: The participants had a mean age ± standard deviation of 60 ± 13.0 years, and 81.8% had a transtibial amputation. The mean ± standard deviation for the L Test change scores was 6.0 ± 13.9. The area under the curve was 0.67, and the minimal clinically important difference was 4.5 s.

Conclusions: The L Test identified individuals as having an important clinical change. Results must be interpreted with caution, as the accuracy, based on the Global Rating Change scale, is low. Further inquiry into the L Test is encouraged.

Clinical relevance: The L Test can guide the clinical management of individuals with lower limb amputation. Results from this pilot study indicate that individuals with a lower limb amputation who improve by at least 4.5 s on the L Test after an intervention have likely undergone an important change. This result must be interpreted with caution given that the ability of the L Test to correctly identify individuals, who have and have not undergone an important change, using the Global Rating Change scale as the gold standard, is limited because this is a pilot study. It is plausible that the precision of the cut-point threshold could increase or decrease given a larger sample or when using a different method of identifying important clinical change.

Keywords: Responsiveness; ambulation; amputation; minimal clinically important difference; outcome measure.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acceleration
  • Activities of Daily Living*
  • Aged
  • Amputation / methods
  • Amputation / rehabilitation*
  • Amputees / psychology
  • Amputees / rehabilitation*
  • Area Under Curve
  • Artificial Limbs*
  • Cohort Studies
  • Female
  • Follow-Up Studies
  • Humans
  • Lower Extremity / surgery*
  • Male
  • Middle Aged
  • Ontario
  • Pilot Projects
  • Postural Balance
  • Prospective Studies
  • Prosthesis Fitting
  • ROC Curve
  • Risk Assessment
  • Treatment Outcome
  • Walking / physiology*