Background:
Recently, two publications, one from California and one from Taiwan, utilizing administrative data have shown an independent, strong association between traumatic brain injury (TBI) and ischemic stroke (IS). The California analysis suggested TBI was a stronger risk factor for IS than hypertension. To begin the process of assessing whether TBI is really associated with IS with more definitive study types, we assessed the feasibility of obtaining TBI information in a population-based stroke study and characterized the history of TBI among IS patients including the time interval from TBI to stroke.
Methods:
As part of the Brain Attack Surveillance in Corpus Christi Project (BASIC), IS patients (n=439) who completed an interview were asked whether they had ever had a TBI that caused them to lose consciousness. For those IS patients who did have a TBI, we further questioned them as to the number and dates of TBIs and the length of loss of consciousness for the longest event. These questions closely followed the US Department of Defense characterization of TBI. Descriptive statistics were used to summarize history of TBI.
Results:
From 1/2/12 thru 7/7/13, 101 of the 439 (23%) IS stroke patients reported a history of at least one TBI that caused them to lose consciousness. Among patients with TBI, 67% had one TBI, 21% had 2 TBI’s, 10% had 3 or more TBI’s. The median length of time between the last reported TBI and stroke onset was 32 years (Q1: 7 years, Q3: 46 years); 3% had a TBI within 30 days prior to their IS and 9% had TBI within 1 year prior to their IS. The median NIHSS of IS patients with TBI was 3 (Q1: 1, Q3: 8) compared with a median NIHSS of 4 (Q1: 2, Q3: 9) among IS patients without TBI.
Conclusion:
It is feasible to obtain TBI information in this population-based stroke surveillance study where a history of TBI is very common in IS patients. The long interval between TBI to IS suggests a lack of association in most cases. A case-control study would be needed to confirm or refute the striking association of TBI and IS previously seen in administrative data. Further, a population-based study with detailed data collection would allow for discovery of associated mechanisms linking TBI to stroke such as dissection, coagulation disorders and intoxications.
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