Table 1.
Characteristics of Patients Identified by the NLP and Coded Algorithms
| NLP controls (n = 10,857) | NLP cases (n = 507) | Coded cases (n = 1142) | |
|---|---|---|---|
| Female gender, n (%) | 4259 (39.2) | 257 (50.7%) | 571 (50.0) |
| Age, mean (SD)a | 30.29 (18.54) | 28.25 (17.15) | 34.09 (18.36) |
| Pediatric (< 18 years of age), n (%)a | 3842 (35.4) | 222 (43.8) | 294 (25.7) |
| TBI code and morbidity group, n (%)b | 10857 (100) | 507 (100) | 706 (61.8) |
| Skull fracture | 13 (0.1) | 1 (0.2) | 94 (8.2) |
| Contusion | 0 (0) | 0 (0) | 56 (4.9) |
| Hemorrhage | 0 (0) | 1 (0.2) | 120 (10.5) |
| Concussion/loss of consciousness | 6349 (58.5) | 262 (51.7) | 444 (38.9) |
| Other and unspecified head injury | 4918 (45.3) | 253 (49.9) | 560 (49.0) |
| Brain imaging, n (%) | 5714 (52.6) | 157 (31.0) | 544 (47.6) |
| TBI cause, n (%) | |||
| Motor vehicle collision | 3877 (35.7) | 90 (17.8) | 246 (21.5) |
| Fall | 1156 (10.6) | 38 (7.5) | 92 (8.1) |
| Struck by and against | 684 (6.3) | 47 (9.3) | 63 (5.5) |
| Assault | 330 (3.0) | 6 (1.2) | 20 (1.8) |
| Unknown | 4810 (44.3) | 326 (64.3) | 721 (63.1) |
| Any PCS code | 0 | 420 (82.8) | 1142 (100) |
| Two or more PCS codes | 0 | 235 (46.4) | 1142 (100) |
| PCS symptom codesc | |||
| Any | 799 (7.4) | 208 (41.0) | 582 (51.0) |
| Anxiety | 121 (1.1) | 21 (4.1) | 61 (5.3) |
| Apathy | 0 | 0 | 0 (0) |
| Depression | 325 (3.0) | 37 (7.3) | 39 (3.4) |
| Concentration difficulties | 7 (0.1) | 20 (3.9) | 13 (1.1) |
| Dizziness | 232 (2.1) | 91 (17.9) | 148 (13.0) |
| Emotional lability | 0 | 0 | 0 (0) |
| Fatigue | 109 (1.0) | 19 (3.7) | 11 (1.0) |
| Headache | 102 (0.9) | 77 (15.2) | 364 (31.9) |
| Irritable | 1 (0) | 0 | 1 (0.1) |
| Impulsive | 0 | 0 | 0 (0) |
| Memory difficulties | 164 (1.5) | 92 (18.1) | 163 (14.3) |
| Sleep disturbances | 91 (0.8) | 16 (3.2) | 32 (2.8) |
| Other | 34 (0.3) | 7 (1.4) | 31 (2.7) |
Age was determined at the time of the most recent eligible mTBI code in NLP patients and at the time of the first PCS billing code in coded patients.
Some NLP patients received multiple TBI codes on the date of the qualifying event, and some coded cases had multiple TBI codes within the window of 365 days before and 30 days after the first PCS billing code. Each TBI code was mapped to TBI type categories, which is why the row counts exceed the number of individuals in each group.
By definition, all NLP cases had a PCS symptom billing code or keyword. For comparison with coded cases, however, in this table we only report the distribution of symptom codes. Symptom codes had to have been recorded up to 365 days after the eligible mTBI in NLP cases and controls, while in coded cases, symptom codes had to have been recorded on the same day as any PCS code.
NLP, natural language processing; SD, standard deviation; TBI, traumatic brain injury; PCS, post-concussion syndrome.