Adjusted relative risk of traumatic brain injury (TBI) by indicators of psychiatric illness in the year before TBI diagnosis or reference date
| Psychiatric illness indicator | Cases (n=1440) (n (%)) | Controls (n=4320) (n (%)) | Adjusted relative risk* | 95% CI |
|---|---|---|---|---|
| *Relative risk adjusted for age, sex, reference date, and Ambulatory Care Group. Reference group is made up of those without each specific indicator. | ||||
| †Lower limit rounded down to 1.0. | ||||
| ‡Determined by psychiatric ICD-9-CM (International Classification of Diseases, 9th revision, clinical modification), diagnosis, psychiatric medication prescription, or psychiatric service utilisation. | ||||
| CI, confidence interval. | ||||
| Psychiatric ICD-9-CM diagnosis | ||||
| Acute reaction to stress or adjustment reaction | 48 (3.3) | 62 (1.4) | 1.9 | 1.3 to 2.9 |
| Alcohol or drug intoxication, withdrawal, or dependence | 34 (2.4) | 51 (1.2) | 1.6 | 1.0 to 2.6† |
| Anxiety | 26 (1.8) | 38 (0.9) | 1.5 | 0.9 to 2.6 |
| Depression | 54 (3.8) | 87 (2.0) | 1.4 | 1.0 to 2.0 |
| Hyperkinetic disorder | 14 (1.0) | 48 (1.1) | 0.7 | 0.4 to 1.3 |
| Malaise or fatigue | 44 (3.1) | 64 (1.5) | 1.7 | 1.1 to 2.6 |
| Organic non-psychotic disorders | 10 (0.7) | 6 (0.1) | 4.4 | 1.6 to 12.5 |
| Organic psychotic disorders | 15 (1.0) | 11 (0.3) | 3.7 | 1.6 to 8.7 |
| Schizophrenia, hallucination, or paranoia | 17 (1.2) | 26 (0.6) | 1.9 | 1.0 to 3.7 |
| Somatoform disorders | 19 (1.3) | 14 (0.3) | 2.8 | 1.3 to 5.8 |
| Other | 70 (5.0) | 124 (2.9) | 1.3 | 1.0 to 1.9 |
| Psychiatric medication prescription | ||||
| Anxiolytics | 27 (1.9) | 25 (0.6) | 2.4 | 1.3 to 4.2 |
| Antidepressants | 57 (4.0) | 89 (2.1) | 1.5 | 1.1 to 2.2 |
| Antipsychotics | 18 (1.3) | 19 (0.4) | 2.7 | 1.3 to 5.5 |
| Lithium | 6 (0.4) | 11 (0.3) | 1.6 | 0.6 to 4.4 |
| Psychostimulants | 3 (0.2) | 13 (0.3) | 0.5 | 0.2 to 1.9 |
| Major psychiatric illness indicators | ||||
| Psychiatric ICD-9-CM diagnosis | 262 (18.2) | 420 (9.7) | 1.7 | 1.4 to 2.0 |
| Psychiatric medication prescription | 85 (5.9) | 136 (3.2) | 1.6 | 1.2 to 2.1 |
| Psychiatric service utilisation | 151 (10.5) | 307 (7.1) | 1.3 | 1.0 to 1.6† |
| Psychiatric diagnosis and medication | 66 (4.6) | 94 (2.2) | 1.7 | 1.2 to 2.3 |
| Psychiatric diagnosis and utilisation | 73 (5.1) | 126 (2.9) | 1.3 | 1.0 to 1.8 |
| Psychiatric medication and utilisation | 42 (2.9) | 76 (1.8) | 1.3 | 0.8 to 1.9 |
| Diagnosis, medication, and utilisation | 32 (2.2) | 51 (1.2) | 1.3 | 0.8 to 2.1 |
| Any psychiatric illness‡ | 349 (24.2) | 618 (14.3) | 1.6 | 1.4 to 1.9 |