Table 3.
Test-retest reliability of measurement instruments of mobility in 65 older acute medical patients with cognitive impairment
| DEMMI | HABAM | POMA | SPPB | Gait speed a (n = 35) | 5x chair rise test (n = 16) | 2-min walk test (n = 35) | TUGb (n = 33) |
BI mobility subscale | ||
|---|---|---|---|---|---|---|---|---|---|---|
| Scale range and unit | 0–100 points | 0–26 points | 0–28 points | 0–12 points | Ratio scale (meter/second) | Ratio scale (seconds) | Ratio scale (meter) | Ratio scale (seconds) | 0–40 points | |
| Mean ± SD score 1st measure | 38.5 ± 23.4 | 13.5 ± 7.6 | 10.5 ± 9.4 | 2.8 ± 3.2 | 0.62 ± 0.22 | 17.5 ± 4.1 | 71.5 ± 29.0 | 24.0 ± 13.5 | 18.7 ± 13.7 | |
| Mean ± SD score 2nd measure | 38.7 ± 23.9 | 13.7 ± 7.8 | 10.9 ± 9.7 | 3.2 ± 3.6 | 0.67 ± 0.25 | 16.3 ± 5.2 | 75.9 ± 28.7 | 23.0 ± 12.2 | 19.5 ± 14.1 | |
| Mean difference absolute (95% CI) | 0.3 (− 0.5 to 1.1) | 0.2 (− 0.1 to 0.6) | 0.4 (0.0 to 0.8) | 0.4 (0.2 to 0.6) | 0.04 (0.00 to 0.08) | −1.3 (− 3.1 to 0.6) | 4.4 (0.8 to 8.1) | − 1.0 (− 2.6 to 0,6) | 0.9 (0.1 to 1.6) | |
| Mean difference relative to score of 1st measure | < 1% | 1% | 4% | 14% | 6% | 7% | 6% | 4% | 5% | |
| P value for mean difference | 0.52 | 0.22 | 0.04 | < 0.001 | 0.04 | 0.16 | 0.02 | 0.22 | 0.03 | |
| σ2p | 554.304 | 58.267 | 90.143 | 11.087 | 0.049 | 16.317 | 778.484 | 154.555 | 188.450 | |
| σ2o | 0 | 0.01 | 0.062 | 0.074 | 0.001 | 0.44 | 8.221 | 0.169 | 0.288 | |
| σ2residual | 5.239 | 1.106 | 1.153 | 0.372 | 0.007 | 5.838 | 55.479 | 9.999 | 4.519 | |
| ICCAGREEMENT | 0.99 | 0.98 | 0.99 | 0.97 | 0.86 | 0.72 | 0.92 | 0.94 | 0.98 | |
| 95% CI for ICC | 0.99 to 0.99 | 0.97 to 0.99 | 0.98 to 0.99 | 0.92 to 0.98 | 0.75 to 0.93 | 0.38 to 0.89 | 0.84 to 0.96 | 0.88 to 0.97 | 0.96 to 0.99 | |
| P value for ICC | < 0.001 | < 0.001 | < 0.001 | < 0.001 | < 0.001 | < 0.001 | < 0.001 | < 0.001 | < 0.001 | |
| SEMAGREEMENT (absolute value) | 2.29 | 1.06 | 1.10 | 0.67 | 0.09 | 2.51 | 7.98 | 3.19 | 2.19 | |
| SEMAGREEMENT (relative to scale range) | 2.3% | 4.1% | 3.9% | 5.6% | na | na | na | na | 5.5% | |
| SEMAGREEMENT (relative to mean 1st measure) | 5.9% | 7.9% | 10.5% | 23.9% | 14.5% | 14.3% | 11.2% | 13.3% | 11.7% | |
| τ -correlation c | 0.30; P < 0.01 | −0.03; P = 0.77 | 0.38; P < 0.01 | 0.66; P < 0.01 | 0.18; P = 0.14 | 0.33; P = 0.08 | 0.22; P = 0.08 | 0.43; P < 0.01 | 0.15; P = 0.16 | |
| Normal distribution of differencesd | P < 0.001 | P < 0.001 | P < 0.001 | P < 0.001 | P = 0.03 | P = 0.77 | P = 0.01 | P = 0.01 | P < 0.001 | |
| 95% LoA (log as function of X) | −0.11X + 0.3 to 0.11X + 0.3 | −2.7 to 3.2 | −0.22X + 0.4 to 0.22X + 0.4 | −0.34X + 0.4 to 0.34X + 0.4 | −0.34X + 0.04 to 0.34X + 0.04 | −0.35X - 1.3 to 0.35X - 1.3 | − 0.29X + 4.4 to 0.29X + 4.4 | − 0.28X - 1 to 0.28X - 1 | −0.26X + 0.9 to 0.26X + 0.9 | |
| MDC90 | exact | 5.3 | 2.5 | 2.6 | 1.5 | 0.21 | 5.8 | 18.5 | 7.4 | 5.1 |
| rounded up | 6 | 3 | 3 | 2 | na | na | na | na | 6 | |
| MDC95 | exact | 6.3 | 2.9 | 3.1 | 1.9 | 0.25 | 6.9 | 22.1 | 8.8 | 6.1 |
| rounded up | 7 | 3 | 4 | 2 | na | na | na | na | 7 | |
Abbreviations: DEMMI De Morton mobility index, HABAM Hierarchical assessment of balance and mobility, POMA Performance oriented mobility assessment, SPPB Short physical performance battery, TUG Timed up and go test, BI Barthel index, SD Standard deviation, CI Confidence interval, σ2p Variance between patients, σ2o Variance due to systematic differences between observations, σ2residual Residual variance, ICC Intraclass correlation coefficient, SEM Standard error of measurement, LoA Absolute limites of agreement with 95% confidence, X Test score, MDC90 Minimal detectable change with 90% confidence, MDC95 Minimal detectable change with 95% confidence, na Not applicable
agait speed final score: maximum of 2 trials
bTUG final score: mean of 2nd and 3rd trial
cKendall’s Tau correlation between absolute difference and mean scores of two measures
dShapirow Wilk test of Normality