Table 3.
Results using multiple imputation: predictors of change in contamination-related obsessive-compulsive washing symptoms (outcome: change in OCI-R washing scale from t1 to t3), n = 1,220.
| B [CI95%] | β | p | |
|---|---|---|---|
| Step 1 | Model A1 | ||
| Constant | 1.034 [0.434, 1.633] | 0.001 | |
| Age | - 0.008 [−0.018, 0.001] | −0.049 | 0.096 |
| Gendera | −0.218 [−0.487, 0.051] | −0.046 | 0.112 |
| A-levels | 0.088 [−0.182, 0.358] | 0.019 | 0.525 |
| Step 2 | Model A2 | ||
| Constant | −0.581 [−1.101, −0.060] | 0.029 | |
| Age | −0.001[−0.009, 0.007] | −0.005 | 0.839 |
| Gendera | −0.185 [−0.410, 0.041] | −0.039 | 0.108 |
| A-levelsb | 0.102 [−0.124, 0.328] | 0.022 | 0.378 |
| OCI-R washing subscale (t1) | 0.502 [0.459, 0.546] | 0.547 | < 0.001 |
| χ2(1) = 433.57, p < 0.001 | |||
| Step 3 | Model A3 | ||
| Constant | −0.704 [−1.276, −0.211] | 0.009 | |
| Age | −0.001 [−0.009, 0.007] | −0.006 | 0.829 |
| Gendera | −0.173 [−0.398, 0.052] | −0.037 | 0.132 |
| A-levelsb | 0.112 [−0.114, 0.338] | 0.024 | 0.332 |
| OCI − R washing subscale (t1) | 0.506 [0.462, 0.549] | 0.551 | < 0.001 |
| Change in duration of handwashing (t1-t2) | 0.142[0.030, 0.254] | 0.067 | 0.013 |
| χ2(1) = 6.13, p = 0.013 | |||
| Step 4 | Model A4 | ||
| Constant | −0.743 [−1.276, −0.211] | 0.006 | |
| Age | −0.001 [−0.009, 0.007] | −0.005 | 0.829 |
| Gendera | −0.171 [−0.396, 0.054] | −0.037 | 0.136 |
| A-levelsb | 0.108 [−0.118, 0.334] | 0.023 | 0.348 |
| OCI-R washing subscale (t1) | 0.507 [0.463, 0.550] | 0.552 | < 0.001 |
| Change in duration of handwashing (t1-t2) | 0.132 [0.019, 0.246] | 0.063 | 0.022 |
| Change in frequency of handwashing (t1-t2) | 0.054 [−0.035, 0.142] | 0.033 | 0.234 |
| χ2(1) = 1.43, p = 0.232 | |||
| Step 5 | Model A5 | ||
| Constant | −0.764 [−1.295, −0.233] | 0.005 | |
| Age | −0.001 [−0.009, 0.008] | −0.004 | 0.878 |
| Gendera | −0.182 [−0.406, 0.043] | −0.039 | 0.113 |
| A-levelsb | 0.128 [−0.097, 0.354] | 0.027 | 0.265 |
| OCI-R washing subscale (t1) | 0.504 [0.461, 0.548] | 0.549 | < 0.001 |
| Change in duration of handwashing (t1–t2) | 0.127 [0.014, 0.239] | 0.060 | 0.028 |
| Change in frequency of handwashing (t1–t2) | 0.044 [−0.044, 0.132] | 0.028 | 0.322 |
| Change in negative reinforcement after handwashing (t1) | 0.180 [0.053, 0.306] | 0.074 | 0.005 |
| χ2(1) = 7.82, p = 0.005 | |||
R2 = 0.006, F = 2.481 (p = 0.059) for step 1; ∆R2 = 0.297, F = 132.275 (p < 0.001) for step 2; ∆R2 = 0.005, F = 107.051 (p < 0.001) for step 3; ∆R2 = 0.001, F = 89.483 (p < 0.001) for step 4; ∆R2 = 0.006, F = 77.769 (p < 0.001) for step 5. b, unstandardized regression coefficient; β, standardized regression coefficient; χ2, Chi-Square test statistic for model comparison to the previous step via LRT; OCI-R, Obsessive-Compulsive Inventory-Revised; a1 = male, 2 = female, b0 = no A-level, 1 = A-level and above.