Reliability and validity of the German translation of the de Morton Mobility Index (DEMMI) performed by physiotherapists in patients admitted to a sub-acute inpatient geriatric rehabilitation hospital.
BACKGROUND
Mobility is a key outcome in geriatric rehabilitation. The de Morton Mobility Index (DEMMI) is an internationally well-established, unidimensional measure of mobility with good psychometric properties. The aim of this study was to examine the reliability and construct validity of the German translation of the DEMMI in geriatric inpatients.


METHODS
This cross-sectional study included patients admitted to a sub-acute inpatient geriatric rehabilitation hospital (reliability sample: N = 33; validity sample: N = 107). Reliability, validity, and unidimensionality were investigated.


RESULTS
Inter-rater reliability between two graduate physiotherapists was excellent, with intra-class correlation coefficient of 0.94 (95% confidence interval: 0.88-0.97). The minimal detectable change with 90% confidence was 9 points. Construct validity for the DEMMI was evidenced by significant moderate to strong correlations with other measures of mobility and related constructs (Performance Oriented Mobility Assessment: rho = 0.89; Functional Ambulation Categories: rho = 0.70; six-minute walk test: rho = 0.73; gait speed: rho = 0.67; Falls Efficacy Scale International: rho = -0.68). Known-groups validity was indicated by significant DEMMI mean group differences between independent versus dependent walkers and walking aid users versus non-users. Unidimensionality of the German DEMMI translation was confirmed by Rasch analysis.


CONCLUSIONS
The German translation of the DEMMI is a unidimensional instrument producing valid and reproducible measurement of mobility in an inpatient geriatric rehabilitation setting.
Department of Applied Health Sciences, Physiotherapy Program, Hochschule für Gesundheit, Universitätsstr. 105, 44789, Bochum, Germany. tobias.braun@hs-gesundheit.de.|University of Cologne, Medical Faculty, Kerpener Str. 62, 50937, Cologne, Germany. tobias.braun@hs-gesundheit.de.
Tobias
T
Braun
Department of Geriatric Medicine, St. Marien-Hospital, Kunibertskloster 11-13, 50668, Cologne, Germany. ralf-joachim.schulz@cellitinnen.de.
Ralf-Joachim
RJ
Schulz
Catholic Clinic Bochum, Ruhr-University Bochum, Marien-Hospital Wattenscheid, Parkstr. 15, 44866, Bochum, Germany. reinke@mhwat.de.
Julia
J
Reinke
Health~Holland, Topsector Life Sciences and Health, 2509, The Hague, The Netherlands. meeteren@health-holland.com.|CAPHRI, Maastricht University, Minderbroedersberg 4-6, 6211 LK, Maastricht, The Netherlands. meeteren@health-holland.com.
Nico L
NL
van Meeteren
Donvale Rehabilitation Hospital, Ramsay Health, 1119 Doncaster Road, Donvale, VIC, 3111, Australia. demortonn@ramsayhealth.com.au.
Natalie A
NA
de Morton
School of Allied Health, College of Science, Health and Engineering, La Trobe University, Melbourne, VIC, 3086, Australia. m.davidson@latrobe.edu.au.
Megan
M
Davidson
Department of Applied Health Sciences, Physiotherapy Program, Hochschule für Gesundheit, Universitätsstr. 105, 44789, Bochum, Germany. christian.thiel@hs-gesundheit.de.
Christian
C
Thiel
Department of Applied Health Sciences, Physiotherapy Program, Hochschule für Gesundheit, Universitätsstr. 105, 44789, Bochum, Germany. christian.grueneberg@hs-gesundheit.de.
Christian
C
Grüneberg
D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005080:Exercise Test; D005260:Female; D005684:Gait / Q000502:physiology*; D015577:Geriatric Assessment; D005858:Germany; D006760:Hospitalization; D006801:Humans; D008297:Male; D051346:Mobility Limitation; D009043:Motor Activity / Q000502:physiology*; D011594:Psychometrics; D015203:Reproducibility of Results; D014177:Translations