OR estimates of substance use before injury with every control period and total, by type of substance and measurement
| First control period | Second control period | Multiple matching | |||||||
| obs† | OR | 95% CI | obs† | OR | 95% CI | obs† | OR | 95% CI | |
| Alcohol | |||||||||
| Self-report | 664 | 5.62* | (2.65 to 11.93) | 606 | 5.71* | (2.56 to 12.76) | 967 | 5.49* | (3.06 to 9.84) |
| Alcosensor (BAC≥0.001) | 516 | 3.67* | (1.75 to 7.66) | 470 | 3.22* | (1.53 to 6.81) | 751 | 3.70* | (2.04 to 6.72) |
| Self-report or alcosensor | 664 | 6.25* | (2.96 to 13.18) | 606 | 6.43* | (2.90 to 14.25) | 967 | 6.14* | (3.45 to 10.93) |
| Alcosensor or SR if missing | 664 | 3.55* | (1.82 to 6.92) | 606 | 3.00* | (1.56 to 5.77) | 967 | 3.43* | (2.02 to 5.83) |
| Cannabis | |||||||||
| Self-report | 658 | 1.30 | (0.57 to 2.96) | 604 | 0.80 | (0.32 to 2.03) | 962 | 1.12 | (0.50 to 2.47) |
| Oral fluid | 484 | 0.67 | (0.27 to 1.63) | 448 | 0.77 | (0.34 to 1.75) | 710 | 0.69 | (0.31 to 1.57) |
| Self-report or oral fluid | 658 | 2.22* | (1.01 to 4.88) | 604 | 1.89 | (0.84 to 4.24) | 962 | 2.40* | (1.18 to 4.88) |
| Oral fluid or SR if missing | 658 | 0.86 | (0.40 to 1.85) | 604 | 0.75 | (0.35 to 1.59) | 962 | 0.83 | (0.41 to 1.67) |
ORs were estimated using conditional logistic regression.
*P<0.05.
†obs are the number of case and control periods used in each model (ie, each person contributed with a maximum of three observed case and control periods for the multiple matching models).
BAC, breath alcohol concentration; SR, self-report.