Objective: To determine whether menstrual cycle phase in women at the time of mild traumatic brain injury (mTBI) predicts 1-month outcomes.
Setting: Six emergency departments; 5 in Upstate New York, and 1 in Pennsylvania.
Participants: One hundred forty-four female participants (age, 16-60) who presented to participating emergency departments within 4 hours of mTBI.
Design: Nested cohort study with neurologic and quality-of-life outcome assessment, 1 month after enrollment. Female subjects aged 16 to 60 enrolled in the parent cohort study, with 1-month neurological determination data available, were classified into menstrual cycle groups by serum progesterone concentration and self-reported contraceptive use.
Main measures: Rivermead Post Concussion Questionnaire and EuroQoL/EQ5D.
Results: Women injured during the luteal phase of their menstrual cycle, when progesterone concentration is high, had significantly lower EuroQoL General Health Ratings and Index Scores than women injured during the follicular phase of their cycle or women taking oral contraceptives. Multivariate analysis confirmed a significant independent effect of menstrual cycle phase on EuroQoL Index Score and the Rivermead Post Concussion Questionnaire Somatic Subscore.
Conclusion: Menstrual cycle phase and progesterone concentration at the time of mTBI affect 1-month quality-of-life and neurologic outcomes. This association has important implications for treatment and prognosis after mTBI.