Table 2.
Scale variables measured on both driver and study partner at pre- and post-intervention are summarized. Differences between driver and study partner responses are tested with paired t-tests for continuous variables and McNemar’s tests for binary variables. Concordance (95% CI) is presented with Lin’s concordance correlation coefficient to measure agreement in continuous variables and Cohen’s kappa statistic for binary variables; it is not presented for variables with >2 levels.
| N (%) or mean (SD) | Driver (N = 228) | Study partner (N = 228) | p value | Concordance measure (95% CI) |
|---|---|---|---|---|
| Pre-intervention | ||||
| Decisional conflict scale (DCS) score a | 18.5 (12.3) | 20.5 (16.8) | 0.087 | 0.17 (0.04, 0.29) |
| DCS < 25 | 143 (65.0%) | 131 (58.2%) | 0.122 | 0.09 (−0.04, 0.22) |
| DCS subscale: informed | 18.3 (15.7) | 21.2 (20.4) | 0.088 | 0.02 (−0.10, 0.15) |
| DCS subscale: values clarity | 19.0 (15.9) | 18.8 (19.5) | 0.926 | 0.10 (−0.03, 0.23) |
| DCS subscale: support | 16.8 (14.9) | 17.5 (16.9) | 0.643 | 0.08 (−0.05, 0.21) |
| DCS subscale: uncertainty | 23.5 (19.7) | 24.7 (23.1) | 0.530 | 0.19 (0.06, 0.31) |
| DCS subscale: effective decision | 15.9 (13.2) | 20.0 (18.2) | 0.003 | 0.14 (0.02, 0.26) |
| When you think about [the driver] driving, which way are you leaning? | 6.6 (0.9) | 6.3 (1.3) | <0.001 | 0.19 (0.07, 0.30) |
| 1 (Leaning Toward Stopping Driving) | 0 (0.0%) | 3 (1.3%) | ||
| 2 | 2 (0.9%) | 2 (0.9%) | ||
| 3 | 1 (0.4%) | 7 (3.1%) | ||
| 4 (Undecided) | 9 (3.9%) | 10 (4.4%) | ||
| 5 | 9 (3.9%) | 18 (7.9%) | ||
| 6 | 23 (10.1%) | 41 (18.0%) | ||
| 7 (Leaning Toward Continuing Driving) | 184 (80.7%) | 147 (64.5%) | ||
| Post-intervention | ||||
| Decisional conflict scale (DCS) score a | 14.2 (13.4) | 16.7 (14.9) | 0.024 | 0.22 (0.09, 0.34) |
| DCS < 25 | 162 (71.7%) | 143 (63.3%) | 0.050 | 0.05 (−0.08, 0.18) |
| DCS subscale: informed | 11.7 (15.0) | 14.3 (15.7) | 0.051 | 0.14 (0.02, 0.27) |
| DCS subscale: values clarity | 13.1 (15.1) | 14.5 (16.0) | 0.278 | 0.18 (0.06, 0.31) |
| DCS subscale: support | 12.9 (15.6) | 15.1 (16.2) | 0.131 | 0.11 (−0.02, 0.24) |
| DCS subscale: uncertainty | 18.6 (18.7) | 21.8 (21.6) | 0.061 | 0.22 (0.09, 0.33) |
| DCS subscale: effective decision | 14.2 (14.3) | 17.4 (16.2) | 0.013 | 0.22 (0.09, 0.33) |
| When you think about [the driver] driving, which way are you leaning? b | 6.7 (0.7) | 6.2 (1.2) | <0.001 | 0.15 (0.05, 0.25) |
| 1 (Leaning Toward Stopping Driving) | 0 (0.0%) | 2 (0.9%) | ||
| 2 | 0 (0.0%) | 2 (0.9%) | ||
| 3 | 1 (0.4%) | 8 (3.5%) | ||
| 4 (Undecided) | 5 (2.2%) | 10 (4.4%) | ||
| 5 | 6 (2.6%) | 22 (9.7%) | ||
| 6 | 40 (17.6%) | 57 (25.1%) | ||
| 7 (Leaning Toward Continuing Driving) | 175 (77.1%) | 126 (55.5%) |
Note.
DCS scores could be calculated at pre-intervention for N = 220 drivers and N = 225 study partners and for N = 226 drivers and N = 226 study partners post-intervention. Total DCS scores could not be calculated for those missing any number of components of the 16 DCS questions.
The denominator for both drivers and study partners was N = 227 when asked which way they were leaning about driving post-intervention.