Validity of the de Morton Mobility Index (DEMMI) for measuring the mobility of patients with hip fracture during rehabilitation

Disabil Rehabil. 2013 Feb;35(4):325-33. doi: 10.3109/09638288.2012.705220. Epub 2012 Aug 16.


Purpose: Many patients suffer long term loss of mobility after hip fracture but there is no gold standard method for measuring mobility in this group. We aimed to validate a new mobility outcome measure, the de Morton Mobility Index (DEMMI) in a hip fracture population during inpatient rehabilitation.

Method: The DEMMI was compared with the existing measures of activity limitation: 6 minute walk test, 6 metre walk test and Barthel Index on 109 consecutive patients admitted to rehabilitation after surgery for hip fracture. Patients were assessed by a physiotherapist at admission and discharge. Scale width, validity, minimal clinically important difference (MCID), responsiveness, and unidimensionality were investigated.

Results: Evidence of convergent, discriminant and known groups validity were obtained for the DEMMI. Responsiveness was similar across instruments and the MCIDs were consistent with previous reports. A floor effect was identified for the 6 metre walk test and 6 minute walk test at hospital admission. Rasch analysis identified that the DEMMI maintains its unidimensional properties in this population.

Conclusions: The DEMMI has a broader scale width than existing measures of activity limitation and provides a unidimensional measure of mobility for hip fracture patients during inpatient rehabilitation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Activities of Daily Living*
  • Adult
  • Aged
  • Exercise Test
  • Female
  • Geriatric Assessment
  • Hip Fractures / rehabilitation*
  • Hospitalization
  • Humans
  • Male
  • Middle Aged
  • Mobility Limitation*
  • Outcome Assessment, Health Care / methods*
  • Psychometrics
  • Psychomotor Performance / physiology
  • Reproducibility of Results
  • Walking / physiology