Table 1. Baseline characteristics of the study population and group of risk factors.
| Derivation sample (n=37 100) | Validation sample (n=10 226) | Risk factor group | |
|---|---|---|---|
| Sex | |||
| Male | 34356 (93%) | 9484 (93%) | 1 |
| Female | 2597 (7%) | 716 (7%) | 1 |
| Age (years) | 36 (27-46) | 36 (26-46) | 1 |
| Immigrant status | |||
| Yes | 11410 (31%) | 3106 (30%) | 1 |
| No | 25690 (69%) | 7120 (70%) | 1 |
| Length of incarceration (months) | |||
| <6 | 25584 (69%) | 7179 (70%) | 1 |
| 6-11 | 6086 (16%) | 1690 (17%) | 1 |
| 12-23 | 3771 (10%) | 920 (9%) | 1 |
| ≥24 | 1659 (4%) | 437 (4%) | 1 |
| Violent index offence | |||
| Yes | 14182 (38%) | 3755 (37%) | 1 |
| No | 22918 (62%) | 6471 (63%) | 1 |
| Previous violent crime | |||
| Yes | 19714 (53%) | 5358 (52%) | 1 |
| No | 17386 (47%) | 4868 (48%) | 1 |
| Marital status | |||
| Unmarried | 22565 (65%) | 6134 (64%) | 2 |
| Married | 14535 (35%) | 4092 (36%) | 2 |
| Education (years) | |||
| <9 | 16697 (48%) | 4847 (50%) | 2 |
| 9-11 | 15816 (46%) | 4203 (44%) | 2 |
| ≥12 | 2111 (6%) | 538 (6%) | 2 |
| Employment | |||
| Yes | 8781 (25%) | 2416 (25%) | 2 |
| No | 28319 (75%) | 7810 (75%) | 2 |
| Disposable income | |||
| Negative | 218 (1%) | 59 (<1%) | 2 |
| Zero | 1942 (6%) | 442 (5%) | 2 |
| Low (<20th percentile) | 18189 (53%) | 5130 (53%) | 2 |
| Medium (20th-80th percentile) | 13869 (40%) | 3857 (40%) | 2 |
| High (>80th percentile) | 406 (1%) | 100 (1%) | 2 |
| Neighbourhood deprivation (standardised score) | 0.39 (-1.18 to 1.47) | 0.35 (-1.16 to 1.61) | 2 |
| Mental health disorders* | |||
| Alcohol use disorder | 8094 (22%) | 2150 (21%) | 3 |
| Drug use disorder | 8680 (23%) | 2355 (23%) | 3 |
| Any mental health disorder | 8281 (22%) | 2658 (26%) | 3 |
| Any severe mental health disorder | 1288 (3%) | 330 (3%) | 3 |
| Any developmental or childhood disorder | 1179 (3%) | 344 (3%) | 3 |
Data are n (%) or median (IQR). *Refers to most recent ICD-10 clinical diagnoses (including comorbidity) in the previous 5 years (including in prison). 2476 (7%) individuals in the derivation sample and 638 (6%) in the validation sample had missing values for civil status, highest education, employment, disposable income, and neighbourhood deprivation. The number of missing values were the same for all these variables, becuase they were from the same register.