Background
Methods
Study population
Measures
Late life mobility item bank (LLM-IB)
Other mobility measures
Biodemographic, clinical and disability measures
Procedure
Data analysis
IRT assumptions
Differential item and differential bundle functioning analysis by sex
IRT analysis: Rasch RSM
Missing data
Results
Sample (n = 593) | Male (n = 252) | Female (n = 341) | |
---|---|---|---|
Age
| |||
Mean (SD) | 76.53 (4.81) | 76.73 (4.78) | 76.39 (4.84) |
Median | 76 | 76 | 76 |
Range | 70 – 98 | 70 - 96 | 70 – 98 |
Gender (%) | |||
Female | 57.50 | ||
Education (%) | |||
Unable to read/write | 16.69 | 9.13 | 22.29 |
Able to read/write | 58.52 | 59.92 | 57.48 |
Primary | 16.86 | 19.44 | 14.97 |
Secondary or higher | 7.93 | 11.51 | 5.28 |
Living (%) | |||
Couple | 60.03 | 79.37 | 45.75 |
Family | 14.84 | 8.73 | 19.35 |
Alone | 25.13 | 11.90 | 34.90 |
Morbidity Index (%) | |||
0-1 | 21.92 | 29.37 | 16.42 |
2 | 23.44 | 22.62 | 24.05 |
+2 | 54.64 | 48.01 | 59.53 |
Mean (SD) | 2.90 (1.78) | 2.65 (1.78) | 3.08 (1.76) |
Body Mass Index
| |||
Mean (SD) | 29.12 (4.28) | 28.14 (3.81) | 29.85 (4.46) |
Cognitive Status
| |||
SPMSQ: mean (SD) | 1.58 (1.12) | 1.35 (1.01) | 1.75 (1.11) |
Functional Status
| |||
ADL dependence:% | 6.41 | 3.57 | 8.50 |
SPPB: mean (SD) | 8.35 (2.73) | 9.17 (2.41) | 7.74 (2.80) |
PF-10: mean (SD) | 67.90 (26.35) | 76.38 (22.45) | 61.59 (27.29) |
65.70 (29.80)* | 73.30 (27.00) * | 63.10 (25.10) * |
Descriptive analysis of the item pool
IRT asumptions
Models | CFI | NNFI (TLI) | RMSEA | SRMR | Satorra-Bentler χ2 | df |
---|---|---|---|---|---|---|
Single | .99 | .99 | .072 | .056 | 3816.72* | 945 |
Bifactor | 1.00 | .99 | .048 | .040 | 2126.52* | 900 |
Single (female) | .99 | .99 | .072 | .061 | 2475.04* | 902 |
Bifactor (female) | .99 | .99 | .051 | .047 | 1599.65* | 858 |
Single (male) | .99 | .99 | .072 | .083 | 2079.19* | 902 |
Bifactor (male) | .99 | .99 | .055 | .067 | 1506.36* | 858 |
Standard cutoff val. | > .95 | > .95 | < .06 | < .08 |
DBF and DIF analysis
Item Wording | External criteria | ||||||
---|---|---|---|---|---|---|---|
Internal criterion | PF-10 | SPPB | |||||
Beta | p | Beta | p | Beta | p | ||
Walking (W) | |||||||
W01 | Walk around the house | -.01 | .75 | -.02 | .41 | -.03 | .32 |
W02 | Walk without losing balance | .02 | .56 | .03 | .38 | .01 | .71 |
W03 | Walk without tripping | .05 | .13 | .07 | .03 | .07 | .07 |
W04 | Walk outdoors | -.06 | .06 | -.05 | .25 | -.08 | .07 |
W05 | Walk 5 minutes nonstop | -.04 | .23 | -.03 | .40 | -.05 | .19 |
W06 | Cross the road | .04 | .06 | .05 | .11 | .01 | .82 |
W07 | Walk 1 kilometre with rests | -.08 | .07 | -.04 | .43 | -.11 | .03 |
W08 | Walk on a slippery surface | .01 | .80 | .06 | .19 | .01 | .87 |
W09 | Walk 15 minutes nonstop | -.07 | .08 | -.09 | .04 | -.12 | .02 |
W10 | Walk 5 minutes at a fast pace | .14 | .01 | -.11 | .05 | -.14 | .01 |
W11 | Walk 2 kilometres nonstop | -.21 | .00 | -.14 | .01 | -.17 | .00 |
W12 | Walk several kilometres on uneven ground | -.03 | .58 | .04 | .40 | -.01 | .93 |
W13 | Walk half an hour at a fast pace nonstop | -.14 | .01 | -.04 | .50 | -.07 | .30 |
W14 | Climb a steep hill | -.02 | .59 | .07 | .07 | .09 | .06 |
W15 | Run a short distance | -.05 | .05 | .02 | .68 | -.01 | .91 |
W16 | Run one and a half kilometres | -.08 | .06 | .04 | .43 | .02 | .71 |
DBF | -.14 | -.58 | |||||
Average DBF (DBF/n items) | -.01 | -.04 | |||||
Up and down stairs (UDS) | |||||||
UDS01 | Climb 4 or 5 steps, using handrails | .05 | .09 | .03 | .28 | .05 | .19 |
UDS02 | Step up and down from a curb | .01 | .76 | .06 | .09 | .02 | .58 |
UDS03 | Climb 4 or 5 steps, without handrails | .06 | .18 | .10 | .05 | .06 | .30 |
UDS04 | Go down 4 or 5 steps, using handrails | .05 | .11 | .04 | .17 | .03 | .34 |
UDS05 | Get on and off a bus | .05 | .17 | .11 | .01 | .06 | .14 |
UDS06 | Go down 4 or 5 steps, without handrails | .06 | .15 | .13 | .01 | .10 | .07 |
UDS07 | Go up 1 flight of stairs, without handrails | .02 | .74 | .10 | .06 | .08 | .19 |
UDS08 | Go down 1 flight of stairs, using handrails | .05 | .11 | .06 | .07 | .06 | .10 |
UDS09 | Climb stairs carrying little weight | -.05 | .17 | -.04 | .29 | -.02 | .61 |
UDS10 | Go up 3 flights of stairs, using handrails | .02 | .60 | .06 | .13 | .07 | .14 |
UDS11 | Go down 3 flights of stairs, using handrails | .01 | .70 | .03 | .42 | .05 | .32 |
DBF | .68 | .56 | |||||
Average DBF (DBF/n items) | .06 | .05 | |||||
Body Position (BP) | |||||||
BP01 | Get into bed† | - | - | - | - | - | - |
BP02 | Turn over in bed | .01 | .91 | .05 | .29 | .06 | .15 |
BP03 | Sit down on a couch | .02 | .50 | .05 | .16 | .02 | .54 |
BP04 | Sitting, bend over to pick something up | -.04 | .32 | -.02 | .66 | .01 | .81 |
BP05 | Remain seated for 10 minutes without back rest | .07 | .05 | .13 | .00 | .16 | .00 |
BP06 | Sit up in bed, being lied down | -.03 | .47 | -.01 | .74 | -.00 | .97 |
BP07 | Sit down and stand up from a chair† | - | - | - | - | - | - |
BP08 | Stand up from a low, soft couch | .10 | .03 | .09 | .04 | .08 | .11 |
BP09 | Pick up a chair† | - | - | - | - | - | - |
BP10 | Reach overhead while standing | .19 | .00 | .22 | .00 | .26 | .00 |
BP11 | Turn around while standing | .07 | .09 | .08 | .04 | .09 | .04 |
BP12 | Remain standing for 10 minutes | -.03 | .50 | -.01 | .83 | .00 | .98 |
BP13 | Standing, bend down to pick something up | -.04 | .37 | .01 | .80 | .01 | .80 |
BP14 | Get up from the floor from lying on your back | .20 | .00 | .24 | .00 | .23 | .00 |
BP15 | Kneel down | .29 | .00 | .32 | .00 | .32 | .00 |
BP16 | Get into and out of a car | .03 | .53 | .08 | .06 | .08 | .06 |
DBF | 1.23 | 1.32 | |||||
Average DBF (DBF/n items) | .09 | .10 | |||||
Carrying, Lifting and Pushing (CLP) | |||||||
CLP01 | Push or pull a large object | .07 | .09 | .12 | .01 | .13 | .01 |
CLP02 | Move or drag a bed | .11 | .02 | .13 | .00 | .16 | .00 |
CLP03 | Lift 4 or 5 kg from the floor | .17 | .00 | .22 | .00 | .25 | .00 |
CLP04 | Turn over a mattress | .10 | .04 | .14 | .00 | .18 | .00 |
CLP05 | Change gas bottle | .23 | .00 | .22 | .00 | .23 | .00 |
DBF | .83 | .95 | |||||
Average DBF (DBF/n items) | .17 | .19 |
Rasch RSM analysis
Confirmatory factor analysis | Rasch rating scale analysis | |||||||||
---|---|---|---|---|---|---|---|---|---|---|
Single Factor | Bi-factor model | Location (Error) | Infit MNSQ | Outfit MNSQ | ||||||
G | g1 | g2 | g3 | g4 | ||||||
Walking (W) | ||||||||||
W01 | Walk around the house | .88 | .86 | .27 | 3.15 (.15) | .88 | .54 | |||
W02 | Walk without losing balance** | .81 | .80 | .16 | - | - | - | |||
W03 | Walk without tripping | .78 | .78 | .06 | 1.71 (.11) | 1.02 | 1.47 | |||
W04 | Walk outdoors | .89 | .86 | .29 | .91 (.10) | .78 | .72 | |||
W05 | Walk 5 minutes nonstop | .83 | .79 | .33 | 2.12 (.12) | 1.13 | .73 | |||
W06 | Cross the road | .87 | .87 | .17 | 2.02 (.12) | .91 | .77 | |||
W07 | Walk 1 kilometre with rests | .89 | .83 | .40 | .50 (.09) | .98 | .81 | |||
W08 | Walk on a slippery surface | .82 | .82 | .14 | - .84 (.09) | .95 | 1.29 | |||
W09 | Walk 15 minutes nonstop | .88 | .81 | .46 | .84 (.10) | 1.03 | .95 | |||
W10 | Walk 5 minutes at a fast pace | .87 | .80 | .44 | - .74 (.09) | 1.22 | 1.00 | |||
W11 | Walk 2 kilometres nonstop | .90 | .84 | .43 | - .66 (.09) | 1.03 | .83 | |||
W12 | Walk several kilometres on uneven ground | .88 | .85 | .27 | - 1.53 (.08) | .90 | .84 | |||
W13 | Walk half an hour at a fast pace nonstop | .88 | .81 | .46 | - 2.47 (.09) | 1.04 | .90 | |||
W14 | Climb a steep hill | .81 | .80 | .20 | - 1.06 (.09) | .89 | 1.29 | |||
W15 | Run a short distance | .88 | .86 | .26 | - 2.31 (.09) | 1.08 | .89 | |||
W16 | Run one and a half kilometres | .83 | .80 | .30 | - 4.30 (.10) | 1.29 | .97 | |||
Up and down stairs (UDS) | ||||||||||
UDS01 | Climb 4 or 5 steps, using handrails | .86 | .83 | .40 | 1.89 (.11) | .87 | .72 | |||
UDS02 | Step up and down from a curb | .86 | .87 | .11 | 1.42 (.11) | .81 | .80 | |||
UDS03 | Climb 4 or 5 steps, without handrails | .93 | .93 | .16 | - .31 (.09) | .97 | .77 | |||
UDS04 | Go down 4 or 5 steps, using handrails** | .80 | .75 | .54 | - | - | - | |||
UDS05 | Get on and off a bus | .88 | .89 | .03 | .22 (.09) | .74 | .69 | |||
UDS06 | Go down 4 or 5 steps, without handrails | .92 | .92 | .15 | - .47 (.09) | .98 | .87 | |||
UDS07 | Go up 1 flight of stairs, without handrails | .90 | .91 | .10 | - 1.54 (.08) | .91 | .88 | |||
UDS08 | Go down 1 flight of stairs, using handrails | .90 | .88 | .34 | 1.42 (.11) | .74 | .70 | |||
UDS09 | Climb stairs carrying little weight | .87 | .86 | .26 | .64 (.10) | .87 | .83 | |||
UDS10 | Go up 3 flights of stairs, using handrails | .88 | .88 | .22 | - .98 (.09) | .75 | .79 | |||
UDS11 | Go down 3 flights of stairs, using handrails | .89 | .88 | .26 | - .29 (.09) | .80 | .75 | |||
Body positions (BP) | ||||||||||
BP01 | Get into bed† | - | - | - | - | - | ||||
BP02 | Turn over in bed** | .62 | .60 | .32 | - | - | - | |||
BP03 | Sit down on a couch | .83 | .83 | .23 | 1.48 (.11) | 1.18 | .80 | |||
BP04 | Sitting, bend over to pick something up | .75 | .72 | .46 | 0.83 (.10) | 1.25 | 1.23 | |||
BP05 | Remain seated for 10 minutes without back rest** | .76 | .76 | .20 | - | - | - | |||
BP06 | Sit up in bed, being lied down** | .72 | .71 | .25 | - | - | - | |||
BP07 | Sit down and stand up from a chair† | - | - | - | - | - | ||||
BP08 | Stand up from a low, soft couch | .80 | .79 | .21 | - .87 (.09) | 1.01 | 1.16 | |||
BP09 | Pick up a chair† | - | - | - | - | - | ||||
BP10 | Reach overhead while standing* | .74 | .73 | .26 | - | - | - | |||
BP11 | Turn around while standing** | .70 | .69 | .23 | - | - | - | |||
BP12 | Remain standing for 10 minutes | .82 | .83 | .03 | - .15 (.09) | 1.14 | 1.06 | |||
BP13 | Standing, bend down to pick something up | .79 | .77 | .47 | .02 (.09) | 1.12 | 1.03 | |||
BP14 | Get up from the floor from lying on your back | .83 | .82 | .29 | −1.96 (.08) | .95 | 1.03 | |||
BP15 | Kneel down* | .79 | .79 | .19 | - | - | - | |||
BP16 | Get into and out of a car | .76 | .76 | .20 | .54 (.09) | 1.10 | 1.31 | |||
Carrying, lifting and pushing (CLP) | ||||||||||
CLP01 | Push or pull a large object | .80 | .79 | .42 | .26 (.09) | 1.20 | 1.20 | |||
CLP02 | Move or drag a bed | .81 | .79 | .48 | .12 (.09) | 1.21 | 1.33 | |||
CLP03 | Lift 4 or 5 kg from the floor* | .80 | .80 | .30 | - | - | - | |||
CLP04 | Turn over a mattress | .81 | .80 | .34 | .36 (.09) | 1.21 | 1.14 | |||
CLP05 | Change gas bottle* | .82 | .81 | .39 | - | - | - |