Table 1.
Construct validity of the de Morton Mobility Index (n = 348) including the hypotheses on construct validity and the constructs of the comparison measurement instruments
| No | Hypothesis | Comparison measurement instrument | Observed correlation with DEMMI (Spearman’s correlation) | Hypothesis confirmed | |||
|---|---|---|---|---|---|---|---|
| Measurement instrument | Construct | Mean ± SD (range) or median (IQR) | rho | 95% CI | |||
| 1 | A correlation of > 0.7 was expected between the DEMMI and other measures of mobility and functional independence | POMA, 0–28 points | Mobility | 18 ± 10 (0–28) | 0.94 | 0.93 to 0.95 | Yes |
| 2 | Timed Up and Go test (n = 266), seca | Mobility | 14 ± 11 (4–76) | 0.80 | 0.75 to 0.84 | Yes | |
| 3 | 10-m gait speed, fast (n = 277), m/sec | Mobility | 1.15 ± 0.51 (0.11–2.00) | 0.75 | 0.69 to 0.80 | Yes | |
| 4 | FIM mobility sub-scale (n = 325), 5–35 points | Mobility | 23 ± 8 (5–35) | 0.80 | 0.76 to 0.84 | Yes | |
| 5 | FAC, 0–5 points | Ambulation | 4 (3–5) | 0.89 | 0.87 to 0.91 | Yes | |
| 6 | 6-min walk test (n = 276), meters | Walking endurance | 349 ± 161 (28–664) | 0.82 | 0.78 to 0.86 | Yes | |
| 7 | Berg Balance Scale, 0–56 points | Balance | 36 ± 19 (0–56) | 0.95 | 0.94 to 0.96 | Yes | |
| 8 | FIM total (n = 325), 18–126 points | Functional independence | 86 ± 24 (18–126) | 0.73 | 0.68 to 0.78 | Yes | |
SD standard deviation, IQR interquartile-range, CI confidence interval, DEMMI de Morton Mobility Index, POMA Performance Oriented Mobility Assessment, FIM Functional Independence Measure, FAC Functional Ambulation Categories
a indicates hypothesis of a negative correlation