Base rates of postconcussive symptoms in health maintenance organization patients and controls.

This study was intended to provide a normative comparison for determining the base rates of postconcussive syndrome (PCS) symptoms in patients from 4 medical departments of a health maintenance organization (HMO) and in people without acute medical or psychological complaints (controls). Recent research suggests that both neurologic and psychosocial factors influence these symptoms. Participants were 1,116 individuals who were surveyed regarding various symptoms, including those reported to be common in the PCS. Endorsement rates are presented for each PCS symptom for controls, each medical sample, and those people with a recent history of being knocked unconscious (2.3%), bumping their heads without losing consciousness (7.4%), and lawsuit involvement (6.8%), which were independently related to most PCS symptoms. The data indicate that neurologic, psychological, and environmental variables are related to having PCS complaints, and such factors should be considered before PCS complaints are used as evidence for brain damage. (PsycINFO Database Record (c) 2010 APA, all rights reserved)