Appendix C:

Logistic Regression Analyses With Predictors Selected in Lasso Shrinkage as Independent Variables and the Rivermead Post Concussion Questionnaire Dichotomized Using Two Different Definitions as Dependent Variable

Variable	PCS defined as ≥3 out of 8 symptoms with score ≥2 (mild problem and worse)‡OR (95% CI)	PCS defined as ≥3 out of 8 symptoms with score ≥3 (moderate problem and worse)OR (95% CI)
Age (/10y)	1.04 (0.89–1.22)	1.16 (0.97–1.39)
Gender (Female vs Male)	2.02 (1.11–3.68)	1.79 (0.93–3.43)
Years of education (/y)	0.84 (0.76–0.93)	0.87 (0.77–0.97)
Pre‐injury migraine & headache (yes vs. no)	1.68 (0.70–4.07)	1.32 (0.57–3.02)
Pre‐injury psychiatric disorders* (yes vs. no)	2.05 (1.14–3.68)	3.24 (1.77–5.91)
Prior TBI (yes vs. no)	2.94 (1.71–5.08)	2.08 (1.10 − 3.93)
PTA
‐ Yes vs. no/unknown	0.60 (0.16–2.23)	1.15 (0.28–4.69)
‐ No vs. yes/unknown	0.49 (0.12–1.98)	0.77 (0.17–3.21)
LOC
‐ Yes vs. no/unknown	1.28 (0.46–3. 59)	0.75 (0.25–2.25)
‐ No vs. yes/unknown	0.92 (0.29–2.92)	0.48 (0.13–1.78)
AUC	0.74	0.76

^‡147 (53%) patients are diagnosed with PCS according to this definition.

74 (27%) patients are diagnosed with PCS according to this definition.

^*Includes anxiety, depression, sleeping disorders, and bipolar disorder.

PCS, post‐concussive syndrome; TBI, traumatic brain injury; PTA, posttraumatic amnesia; LOC, loss of consciousness; AUC, area under the curve.