Natalie A. de Morton

Application of Rasch analysis in health care is increasing and is applied for variable reasons in mobility instruments

OBJECTIVEnTo identify the frequency of Rasch analysis use in health instrument development or refinement and the characteristics of Rasch application in mobility scales.nnnSTUDY DESIGN AND SETTINGnThe entire databases of Medline, CINAHL, PEDro, EMBASE, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews were searched until January 2009. Articles that reported the development or refinement of health instruments using Rasch analysis were included. Of the 234 articles that met inclusion, 10 were categorized as mobility instruments. Data were extracted relating to each instrument and the use of Rasch analysis in the development or refinement of the instruments.nnnRESULTSnThe number of articles reporting the use of Rasch analysis of health instruments is increasing, from 1 article in 1987 to 48 articles in 2007. Of the 10 mobility instruments examined, the primary reason Rasch was used varied. Reasons included assessing instrument unidimensionality, differential item functioning, rating categories, item hierarchy, and redundant items.nnnCONCLUSIONnThe application of Rasch analysis in health instrument development has markedly increased in recent years. However, few mobility instruments have been developed or refined using Rasch analysis. The reasons that the Rasch model was used varied across mobility instruments.

Clinimetric Properties of the de Morton Mobility Index in Healthy, Community-Dwelling Older Adults

OBJECTIVEnTo investigate the clinimetric properties of the de Morton Mobility Index (DEMMI) in healthy, community-dwelling older adults.nnnDESIGNnCohort study.nnnSETTINGnRetirement village and Returned and Services League (RSL) club in Melbourne, Australia.nnnPARTICIPANTSnAll participants were 65 years or older, healthy, and living within the community. The validation study included participants recruited from a retirement village (n=61), and the reliability studies included participants recruited from an RSL club and a subset of participants from the retirement village.nnnINTERVENTIONSnNot applicable.nnnMAIN OUTCOME MEASURESnMobility was assessed using the DEMMI. The percentage of participants who scored the highest and lowest possible score on the DEMMI was calculated to determine whether a floor or ceiling effect occurred. The minimal clinically important difference (MCID) was estimated using a distribution-based method. Reliability was assessed independently and concurrently using the minimal detectable change at 90% confidence (MDC₉₀).nnnRESULTSnEvidence of convergent and discriminant validity was obtained for the DEMMI by examining correlations with measures of related constructs, the Lower Extremity Functional Scale (r=.69) and Quality of Life Scale scores (r=.28), respectively. Participants who ambulated without a gait aid (82.62±10.63) had significantly higher (P<.0) DEMMI scores than those who ambulated with an aid (64.1±12.40), providing evidence of known groups validity. No floor or ceiling effect was identified. The MCID was 7 points. The MDC₉₀ was 13 (95% CI, 8.76-17.05) points on the 100-point scale.nnnCONCLUSIONnDEMMI scores in healthy, community-dwelling older adults are both valid and reliable.

The de Morton Mobility Index (DEMMI) provides a valid method for measuring and monitoring the mobility of patients making the transition from hospital to the community: an observational study.

QUESTIONnIs the de Morton Mobility Index (DEMMI) valid for measuring the mobility of patients making the transition from hospital to the community?nnnDESIGNnObservational cohort study.nnnPARTICIPANTSn696 consecutive patients admitted to 11 Transition Care Programs for multidisciplinary care in Victoria and Tasmania during a 6-month period. The DEMMI and Modified Barthel Index were administered within 5 working days of admission and discharge from the Transition Care Program.nnnOUTCOME MEASURESnThe DEMMI and Modified Barthel Index.nnnRESULTSnNeither the DEMMI nor the Modified Barthel Index had a floor or ceiling effect. Similar evidence of convergent, discriminant and known-groups validity were obtained for each instrument. The DEMMI was significantly more responsive to change than the Modified Barthel Index using criterion- and distribution-based methods. The minimum clinically important difference estimates represented similar proportions of the scale width for the DEMMI and Modified Barthel Index and were similar using criterion- and distribution-based estimates. Rasch analysis identified the DEMMI as essentially unidimensional in a Transition Care Program cohort and therefore can be applied to obtain interval level measurement. Rasch analysis demonstrated that the DEMMI was administered similarly by physiotherapists and allied health assistants under the direction of a physiotherapist.nnnCONCLUSIONnThe DEMMI and Modified Barthel Index are both valid measures of activity limitation for Transition Care Program patients. The DEMMI has a broader scale width, provides interval level measurement, and is significantly more responsive to change than the Modified Barthel Index for measuring the mobility of Transition Care Program patients.

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

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. Implications for Rehabilitation Loss of mobility is a common and significant problem following hip fracture. The de Morton Mobilitiy Index (DEMMI) is an effective instrument for measuring mobility in patients with hip fracture during rehabilitation The DEMMI is unidimensional, has a broader scale width than existing measures and offers an interval scale for measurement of mobility in hip fracture during rehabilitation

Reproducibility and validity of the Dutch translation of the de Morton Mobility Index (DEMMI) used by physiotherapists in older patients with knee or hip osteoarthritis.

OBJECTIVEnTo examine the reproducibility, construct validity, and unidimensionality of the Dutch translation of the de Morton Mobility Index (DEMMI), a performance-based measure of mobility for older patients.nnnDESIGNnCross-sectional study.nnnSETTINGnRehabilitation center (reproducibility study) and hospital (validity study).nnnPARTICIPANTSnPatients (N=28; age >65y) after orthopedic surgery (reproducibility study) and patients (N=219; age >65y) waiting for total hip or total knee arthroplasty (validity study).nnnINTERVENTIONnNot applicable.nnnMAIN OUTCOME MEASURESnNot applicable.nnnRESULTSnThe intraclass correlation coefficient for interrater reliability was high (.85; 95% confidence interval, 71-.93), and minimal detectable change with 90% confidence was 7 on the 100-point DEMMI scale. Rasch analysis identified that the Dutch translation of the DEMMI is a unidimensional measure of mobility in this population. DEMMI scores showed high correlations with scores on other performance-based measures of mobility (Timed Up and Go test, Spearman r=-.73; Chair Rise Time, r=-.69; walking test, r=.74). A lower correlation of .44 was identified with the self-report measure Western Ontario and McMaster Universities Osteoarthritis Index.nnnCONCLUSIONSnThe Dutch translation of the DEMMI is a reproducible and valid performance-based measure for assessing mobility in older patients with knee or hip osteoarthritis.

Validation of the de Morton Mobility Index (DEMMI) with older community care recipients

Aim:u2002 To validate the de Morton Mobility Index (DEMMI) in community‐dwelling older adults who require informal care.

What instruments have been used to assess the mobility of community-dwelling older adults?

Abstract Background: The primary aim of this review was to identify existing instruments that have been used to assess the mobility status of community-dwelling older adults. The secondary aims were to identify instruments that have face validity for measuring across the full mobility spectrum and to summarise and compare their clinimetric properties. Methods: MEDLINE, CINAHL, PEDro, and EMBASE were searched until April 2007. The first stage included searching for papers that reported mobility outcome measures that had been applied to healthy community-dwelling older adults. The second stage identified these outcome measures and the third stage compared clinimetric properties of the instruments that had face validity for measuring across the full mobility spectrum (from bed-bound to high levels of independent mobility). Two independent reviewers extracted data from the included studies. Results: From the 128 included papers, 14 outcome measures were identified, two of which, the Lower Extremity Functional Scale (LEFS) and the Elderly Mobility Scale (EMS), measured across the full spectrum of mobility. No clinimetric evidence was found for the LEFS amongst a community-dwelling older population and only evidence of known groups validity was identified for the EMS. Discussion: An outcome measure that has face validity for measuring across the full mobility spectrum and has sufficient clinimetric evidence in a community dwelling population was not identified. Conclusion: This review supports the need for the development of such an instrument.

Measuring mobility in patients living in the community with Parkinson disease

QUESTIONnIs the de Morton Mobility Index (DEMMI) valid for measuring the mobility of patients living in the community with Parkinson disease (PD)?nnnDESIGNnA prospective cohort study comparing the DEMMI with existing mobility-related activity measures.nnnPARTICIPANTSn102 consecutive patients with PD (mean age 72.4 years, SD 8.3) who received multidisciplinary outpatient care in a community rehabilitation facility over 6 to 8 weeks.nnnOUTCOME MEASURES AND ANALYSISnThe DEMMI and other measures of mobility-related activity at admission and discharge (10 metre walk test, Berg balance scale, timed up and go test, functional reach test and pull test) were used to assess convergent validity. Discriminant validity of the DEMMI was assessed by comparison to measures of other constructs, and. unidimensionality was examined using Rasch analysis.nnnRESULTSnEvidence of convergent (rho ranged from 0.47 to 0.84), discriminant (rho ranged 0.12 to 0.22), and known groups validity were obtained for the DEMMI (Mean difference 20.3 units, 95% CI 14.5 to 26.0). Rasch analysis confirmed that the DEMMI was unidimensional.nnnCONCLUSIONnThe DEMMI has a broader scale width than existing mobility-related activity measures, provides interval level measurement and is a unidimensional measure of mobility in patients with PD living in the community.

Factors that predict discharge destination for patients in transitional care: a prospective observational cohort study

OBJECTIVEnTo investigate factors that predict discharge destination for patients making the transition from hospital to the community.nnnMETHODSnUsing a prospective cohort design, 696 patients from 11 Transition Care Programs were recruited. Baseline patient and program characteristics were considered for predicting discharge destination, functional status, and patient length of stay.nnnRESULTSnAn increased physiotherapy staffing ratio in Transition Care Program was associated with an increased likelihood that a patient was discharged home, with an improved functional or mobility status, and after a shorter length of stay. The other factor that predicted discharge to home included having an Aged Care Assessment Service classification of low level care or home with a support package. An increased physiotherapy staffing level also reduced the likelihood of discharge to low level or high level care. The other factors that predicted discharge to low level care were having higher mobility status and older age; the other factor associated with increased likelihood of predicting discharge to high level care was having an Aged Care Assessment Service classification of high level care.nnnCONCLUSIONSnFactors on admission that predicted discharge destination were program physiotherapy staffing ratios, Aged Care Assessment Service assessment, age and mobility status.

Unidimensionality of the Elderly Mobility Scale in older acute medical patients: different methods, different answers

OBJECTIVEnTo investigate the unidimensionality of the Elderly Mobility Scale (EMS) in an older acute medical population.nnnSTUDY DESIGNnEMS data were collected within 48 hours of hospital admission and discharge, respectively, from consecutive older acute medical patients. Rasch and factor analysis of EMS data were conducted.nnnSETTINGnAcute tertiary hospital, South Australia.nnnRESULTSnFactor analysis identified a two-factor solution for both admission and discharge EMS data. At hospital admission (n=120), EMS data fitted the Rasch model (χ(2)=18.31, P=0.19, df=14). One item, the timed walk test, had a high positive fit residual (+3.93). At hospital discharge (n=105), EMS data did not fit the Rasch model (χ(2)=25.66, P=0.03, df=14). Item and person scores were not well matched because of a ceiling effect in discharge EMS scores. The functional reach item showed some misfit to the Rasch model and the gait item had a disordered threshold. After rescoring this disordered threshold, discharge EMS data fitted the Rasch model.nnnCONCLUSIONnConflicting results were identified using a classical test theory and item response theory approach. Although the EMS fitted the Rasch model, an unacceptable ceiling effect at hospital discharge limits the validity of the EMS for measuring and monitoring the mobility of older acute medical patients in the hospital setting.