Object: Regional differences have been shown in patient characteristics and case management within multiple unselected series of patients suffering from traumatic brain injury (TBI). One might expect that such regional heterogeneity would be small in a more selected population of a randomized clinical trial. The goal of this study was to examine what regional differences in patient characteristics, case management, and outcomes exist between continents and among countries within a patient population included in a randomized clinical trial.
Methods: Data were extracted from two concurrently conducted randomized clinical trials of the drug tirilazad; the designs of these studies were similar. The studies included 1701 patients with severe and 476 patients with moderate TBI. Differences were primarily investigated between studies performed in Europe and North America, but also among European regions and between Canada and the United States. Associations among regions and outcomes (6-month mortality rate and Glasgow Outcome Scale scores) were studied using multivariable logistic regression analysis. Comparisons between continents and among regions within Europe showed differences in the distribution of patient ages, causes of injury, and several clinical characteristics (motor score, pupillary reactivity, hypoxia, hypotension, intracranial pressure [ICP]). and findings on computerized tomography scans. Secondary referrals occurred 2.5 times more frequently in Europe. Within Europe secondary referral was mainly associated with an increased proportion of patients with mass lesions (46% in the European Study compared with 40% in the North American Study). Therapy for lowering ICP was more frequently applied in North America. After adjustments for case mix and management, mortality and unfavorable outcomes were significantly higher in Europe (odds ratios = 1.58 and 1.46, respectively). Significant differences in outcome between regions within Europe or within North America were not observed.
Conclusions: Despite the use of a strict study protocol, considerable differences in patient characteristics and case management exist between continents and among countries, reflecting variations in social, cultural, and organizational aspects. Outcomes of TBI may be worse in Europe compared with North America, but this finding requires further study.