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


METHODS
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.
La Trobe University, Musculoskeletal Research Centre and School of Physiotherapy, Bundoora, Australia.
Natalie A
NA
de Morton
Katherine E
KE
Harding
Nicholas F
NF
Taylor
Glenys
G
Harrison
D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D005080:Exercise Test; D005260:Female; D015577:Geriatric Assessment; D006620:Hip Fractures / Q000534:rehabilitation*; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D051346:Mobility Limitation; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011594:Psychometrics; D011597:Psychomotor Performance / Q000502:physiology; D015203:Reproducibility of Results; D016138:Walking / Q000502:physiology