The de Morton Mobility Index (DEMMI): an essential health index for an ageing world.
BACKGROUND
Existing instruments for measuring mobility are inadequate for accurately assessing older people across the broad spectrum of abilities. Like other indices that monitor critical aspects of health such as blood pressure tests, a mobility test for all older acute medical patients provides essential health data. We have developed and validated an instrument that captures essential information about the mobility status of older acute medical patients.


METHODS
Items suitable for a new mobility instrument were generated from existing scales, patient interviews and focus groups with experts. 51 items were pilot tested on older acute medical inpatients. An interval-level unidimensional mobility measure was constructed using Rasch analysis. The final item set required minimal equipment and was quick and simple to administer. The de Morton Mobility Index (DEMMI) was validated on an independent sample of older acute medical inpatients and its clinimetric properties confirmed.


RESULTS
The DEMMI is a 15 item unidimensional measure of mobility. Reliability (MDC(90)), validity and the minimally clinically important difference (MCID) of the DEMMI were consistent across independent samples. The MDC(90) and MCID were 9 and 10 points respectively (on the 100 point Rasch converted interval DEMMI scale).


CONCLUSIONS
The DEMMI provides clinicians and researchers with a valid interval-level method for accurately measuring and monitoring mobility levels of older acute medical patients. DEMMI validation studies are underway in other clinical settings and in the community. Given the ageing population and the importance of mobility for health and community participation, there has never been a greater need for this instrument.
de Morton
Natalie A
NA
Department of Physiotherapy, School of Primary Health Care, Faculty of Medicine, Nursing and Health Sciences, Monash University-Peninsula Campus, PO Box 527, Frankston, Victoria 3199, Australia. natalie.demorton@med.monash.edu.au
Davidson
Megan
M
Keating
Jennifer L
JL
D018806:APACHE; D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D001315:Australia; D005260:Female; D015577:Geriatric Assessment; D006760:Hospitalization; D006801:Humans; D008297:Male; D017063:Outcome Assessment, Health Care; D015203:Reproducibility of Results