1. aKaiser Foundation Rehabilitation Center, Kaiser Permanente Vallejo Medical Center, Vallejo, California
2. bThe Permanente Medical Group, Oakland, California
3. cDivision of Research, Kaiser Permanente, Oakland, California
4. dNapa-Solano Sports Concussion Clinic, Kaiser Permanente Vacaville Medical Center, Vacaville, California
5. eDivision of Injury Prevention, National Center for Injury Prevention and Control, Centers for Disease Control and Prevention, Atlanta, Georgia