DRIVE cohort characteristics, NSW, Australia 2003–2016
| Variable | Category | No self-harm | Self-harm | Missing | Total |
| Gender | Female | 10 104 (54.1) | 509 (58.6) | 744 (58.4) | 11 357 (54.6) |
| Male | 8559 (45.9) | 360 (41.4) | 530 (41.6) | 9449 (45.4) | |
| Age group | 17 | 9070 (48.6) | 450 (51.8) | 608 (47.7) | 10 128 (48.7) |
| 18–19 | 6922 (37.1) | 324 (37.3) | 495 (38.9) | 7741 (37.2) | |
| 20–25 | 2671 (14.3) | 95 (10.9) | 171 (13.4) | 2937 (14.1) | |
| Country of birth | Australia and New Zealand | 16 015 (85.8) | 786 (90.5) | 1082 (84.9) | 17 883 (86.0) |
| Europe | 198 (1.1) | 15 (1.7) | 7 (0.6) | 220 (1.1) | |
| Asia | 1067 (5.7) | 25 (2.9) | 85 (6.7) | 1177 (5.7) | |
| Other | 1336 (7.2) | 43 (5.0) | 86 (6.8) | 1465 (7.0) | |
| Missing | 47 (0.3) | 0 (0.0) | 14 (1.1) | 61 (0.3) | |
| Area-level remoteness | Metro | 13 894 (74.5) | 605 (69.6) | 964 (75.7) | 15 463 (74.3) |
| Inner regional | 3924 (21.0) | 221 (25.4) | 254 (19.9) | 4399 (21.1) | |
| Outer regional/remote | 845 (4.5) | 43 (5.0) | 56 (4.4) | 944 (4.5) | |
| Area-level socioeconomic status | Lowest | 4665 (25.0) | 197 (22.7) | 273 (21.4) | 5135 (24.7) |
| second quartile | 4620 (24.8) | 226 (26.0) | 290 (22.8) | 5136 (24.7) | |
| third quartile | 4831 (25.9) | 239 (27.5) | 383 (30.1) | 5453 (26.2) | |
| Highest | 4547 (24.4) | 207 (23.8) | 328 (25.8) | 5082 (24.4) | |
| Attempts on driver test | 1 | 12 126 (65.0) | 542 (62.4) | 820 (64.4) | 13 488 (64.8) |
| 2 | 4443 (23.8) | 223 (25.7) | 296 (23.2) | 4962 (23.9) | |
| 3 or more | 2036 (10.9) | 100 (11.5) | 152 (11.9) | 2288 (11.0) | |
| Missing | 58 (0.3) | 4 (0.5) | 6 (0.5) | 68 (0.3) | |
| Time on learners licence | < 1 year | 7072 (37.9) | 339 (39.0) | 523 (41.1) | 7934 (38.1) |
| 1–1.5 years | 6649 (35.6) | 324 (37.3) | 443 (34.8) | 7416 (35.6) | |
| > 1.5 years | 4873 (26.1) | 201 (23.1) | 301 (23.6) | 5375 (25.8) | |
| Missing | 69 (0.4) | 5 (0.6) | 7 (0.6) | 81 (0.4) | |
| Crash before study | No | 18 058 (96.8) | 834 (96.0) | 1220 (95.8) | 20 112 (96.7) |
| Yes | 605 (3.2) | 35 (4.0) | 54 (4.2) | 694 (3.3) | |
| Self-rated driving ability compared with other drivers | Much better | 3472 (18.6) | 164 (18.9) | 98 (7.7) | 3734 (18.0) |
| Better | 8131 (43.6) | 390 (44.9) | 247 (19.4) | 8768 (42.1) | |
| Same | 6743 (36.1) | 297 (34.2) | 210 (16.5) | 7250 (34.9) | |
| Worse or much worse | 307 (1.6) | 18 (2.1) | 17 (1.3) | 342 (1.6) | |
| Missing | 10 (0.1) | 0 (0.0) | 702 (55.1) | 712 (3.4) | |
| Lessons with professional driving instructor (hours) driver training (hours) | 0 | 3310 (17.7) | 173 (19.9) | 177 (13.9) | 3660 (17.6) |
| 1–4 | 5371 (28.8) | 272 (31.3) | 272 (21.4) | 5915 (28.4) | |
| 5–8 | 3923 (21.0) | 191 (22.0) | 180 (14.1) | 4294 (20.6) | |
| 9+ | 6059 (32.5) | 233 (26.8) | 645 (50.6) | 6937 (33.3) | |
| Cannabis smoking in last 12 months | Never | 16 209 (86.9) | 571 (65.7) | 501 (39.3) | 17 281 (83.1) |
| Once a month or less | 1831 (9.8) | 207 (23.8) | 59 (4.6) | 2097 (10.1) | |
| 2–4 times a month | 345 (1.9) | 46 (5.3) | 9 (0.7) | 400 (1.9) | |
| 2–3 or >4 times per week | 241 (1.3) | 43 (5.0) | 13 (1.0) | 297 (1.4) | |
| Missing | 37 (0.2) | 2 (0.2) | 692 (54.3) | 731 (3.5) | |
| Use of other drugs in last 12 months | Never | 17 437 (93.4) | 695 (80.0) | 537 (42.2) | 18 669 (89.7) |
| Once a month or less | 885 (4.7) | 120 (13.8) | 28 (2.2) | 1033 (5.0) | |
| 2–4 times a month | 198 (1.1) | 33 (3.8) | 7 (0.6) | 238 (1.1) | |
| 2–3 or >4 times per week | 75 (0.4) | 17 (2.0) | 3 (0.2) | 95 (0.5) | |
| Missing | 68 (0.4) | 4 (0.5) | 699 (54.9) | 771 (3.7) | |
| Alcohol AUDIT-C summary score | 0–6 | 16 268 (87.2) | 663 (76.3) | 527 (41.4) | 17 458 (83.9) |
| >6 | 2390 (12.8) | 206 (23.7) | 64 (5.0) | 2660 (12.8) | |
| Missing | 5 (0.0) | 0 (0.0) | 683 (53.6) | 688 (3.3) | |
| Risk taking behaviour | Low | 6617 (35.5) | 147 (16.9) | 92 (7.2) | 6856 (33.0) |
| Medium | 6060 (32.5) | 282 (32.5) | 119 (9.3) | 6461 (31.1) | |
| High | 5868 (31.4) | 438 (50.4) | 153 (12.0) | 6459 (31.0) | |
| Missing | 118 (0.6) | 2 (0.2) | 910 (71.4) | 1030 (5.0) | |
| Risk perception | Low | 5939 (31.8) | 176 (20.3) | 102 (8.0) | 6217 (29.9) |
| Medium | 5764 (30.9) | 270 (31.1) | 118 (9.3) | 6152 (29.6) | |
| High | 6735 (36.1) | 416 (47.9) | 147 (11.5) | 7298 (35.1) | |
| Missing | 225 (1.2) | 7 (0.8) | 907 (71.2) | 1139 (5.5) | |
| Sensation seeking | Low | 6011 (32.2) | 143 (16.5) | 106 (8.3) | 6260 (30.1) |
| Medium | 6051 (32.4) | 212 (24.4) | 135 (10.6) | 6398 (30.8) | |
| High | 6392 (34.3) | 506 (58.2) | 106 (8.3) | 7004 (33.7) | |
| Missing | 209 (1.1) | 8 (0.9) | 927 (72.8) | 1144 (5.5) | |
| Average weekly driving (hours) | 0–2 | 3721 (19.9) | 141 (16.2) | 187 (14.7) | 4049 (19.5) |
| 3–5 | 5933 (31.8) | 256 (29.5) | 275 (21.6) | 6464 (31.1) | |
| 6–9 | 2985 (16.0) | 139 (16.0) | 156 (12.2) | 3280 (15.8) | |
| 10+ | 6024 (32.3) | 333 (38.3) | 656 (51.5) | 7013 (33.7) |
Area-level socioeconomic status was derived from the Australian Bureau of Statistics 2001 area level Socio-Economic Indexes for Areas index of education and occupation (Trewin, 2001). Geographical remoteness of residence was classified using the Accessibility/Remoteness index of Australia, grouped into three groups (metropolitan, inner and outer regional, remote and very remote) (Trewin, 2004). Alcohol use was measured using a three-item subscale of the Alcohol Use Disorders Identification Test Consumption (AUDIT-C). Question related to self-harm: ‘In the past 12 months have you ever deliberately hurt yourself or done anything that you knew might have harmed you or even killed you?’. Sensation seeking was measured using the Impulsive Sensation Seeking Scale of the Zuckerman Kuhlman Personality Questionnaire.
NSW, New South Wales.