Table 2. Descriptive characteristics of time-invariant and time-varying risk factors for the presence of psychotic features in visits over the first year after study entry.
| Risk Factor | N = 428 |
|---|---|
| Time-invariant risk factors | |
| Persistent clinical or MRI evidence of past TBI* | 43/428 (10.0%) |
| Traumatic events by age 18 (THQ score ≥1) | 330/420 (78.6%) |
| THQ items endorsed by age 18, no. (n = 420) | 2.0 (1.0–4.0) |
| Homelessness by age 18 | 131/424 (30.9%) |
| Time-varying risk factors over the first year after entering study | |
| Any nonprescribed substance use over first year | |
| —Tobacco (any daily use) | 381/428 (89.0%) |
| —Alcohol | 331/427 (77.5%) |
| —Methamphetamine | 198/426 (46.5%) |
| —Cannabis | 310/426 (72.8%) |
| —Cocaine | 312/426 (73.2%) |
| —Opioids | 221/426 (51.9%) |
| Frequency of substance use over first year (users only) days per week | 2.0 (1.0–3.0) |
| —Alcohol use† | 2.0 (1.0–5.0) |
| —Methamphetamine use | 3.0 (1.0–7.0) |
| —Cannabis use | 7.0 (2.0–7.0) |
| —Cocaine use | 5.0 (2.0–7.0) |
| —Opioid use | 7.0 (2.0–7.0) |
| Participants experiencing any traumatic event(s) over first year (rTHQ score ≥1)‡ | 334/410 (81.5%) |
| Months over first year with traumatic events for participants with rTHQ score ≥1 | |
| —Months with no traumatic events | 7 (4–9) |
| —Months with 1 traumatic event | 1 (0–3) |
| —Months with ≥2 traumatic events | 0 (0–1) |
| Homeless ≥1 time over first year | 42/428 (9.8%) |
| Any prescribed substance use over first year | |
| —Adequate antipsychotic treatment | 101/427 (23.7%) |
| —Adequate methadone maintenance therapy | 166/427 (38.9%) |
Data are n/N (%) or median (interquartile range). Abbreviations: CT, computed tomography; MRI, magnetic resonance imaging; rTHQ, recent THQ; TBI, traumatic brain injury; THQ, Trauma History Questionnaire.
*Clinical evidence n = 19 (loss of consciousness ≥5 minutes or confusion ≥1 day AND persistent clinical symptoms such as seizures or cognitive impairment) or MRI/CT evidence (n = 24) of previous TBI.
†For alcohol, users had frequent weeks with no use, so value refers to weeks when using only.
‡rTHQ occurring in the month concurrent with the monthly psychosis assessment visit, carried out by a research assistant.