Incidence of traumatic brain injury across the full disease spectrum: a population-based medical record review study

Abstract

Background: Extremely few objective estimates of traumatic brain injury incidence include all ages, both sexes, all injury mechanisms, and the full spectrum from very mild to fatal events.

Methods: We used unique Rochester Epidemiology Project medical records-linkage resources, including highly sensitive and specific diagnostic coding, to identify all Olmsted County, MN, residents with diagnoses suggestive of traumatic brain injury regardless of age, setting, insurance, or injury mechanism. Provider-linked medical records for a 16% random sample were reviewed for confirmation as definite, probable, possible (symptomatic), or no traumatic brain injury. We estimated incidence per 100,000 person-years for 1987-2000 and compared these record-review rates with rates obtained using Centers for Disease Control and Prevention (CDC) data-systems approach. For the latter, we identified all Olmsted County residents with any CDC-specified diagnosis codes recorded on hospital/emergency department administrative claims or death certificates during 1987-2000.

Results: Of sampled individuals, 1257 met record-review criteria for incident traumatic brain injury; 56% were ages 16-64 years, 56% were male, and 53% were symptomatic. Mechanism, sex, and diagnostic certainty differed by age. The incidence rate per 100,000 person-years was 558 (95% confidence interval = 528-590) versus 341 (331-350) using the CDC data-system approach. The CDC approach captured only 40% of record-review cases. Seventy-four percent of missing cases presented to the hospital/emergency department; none had CDC-specified codes assigned on hospital/emergency department administrative claims or death certificates; and 66% were symptomatic.

Conclusions: Capture of symptomatic traumatic brain injuries requires a wider range of diagnosis codes, plus sampling strategies to avoid high rates of false-positive events.

FIGURE

Distribution by level of evidence of physiologic disruption of brain function for a random sample of all Olmsted County residents who met Rochester Epidemiology Project record-review criteria for traumatic brain injury (n = 1257) (first column) and for specified subsets. Of all record-review cases, the 1056 (84%) with a hospital/emergency department (ED) admission within 2 weeks before to 4 weeks after the event are in the second column. Of the 1056 with such an encounter, the 499 (47%) with any International Classification of Diseases, 9^th Revision, Clinical Modification (ICD-9-CM) diagnosis code for traumatic brain injury consistent with Centers for Disease Control and Prevention (CDC) recommendations in their relevant administrative claims or death certificates are in the third column. In addition to the 499, 10 record-review cases did not present to hospital or emergency department but died with a CDC-recommended code on their death certificate. The distribution of the remaining 748 record-review cases who would have been missed using the CDC data-systems approach recommendations are in the fourth column.