Goldacre et al., 2006

Cohort (population-based record-linkage study) derived from Oxford Record Linkage Study

110,993 people with report of head injury (ICD-9 codes 850–854); ICD-9 534, 600 in reference group; identified January 1, 1963–March 31, 1999

Mild, moderate, severe as determined by length of hospital stay at time of injury (mild, < 2 days; moderate, 2–7 days; severe, > 7 days)

MS and head injury as identified through hospitalizations or deaths in same period (1963–1999)

OR, 1.1 (95% CI, 0.88–1.36; p = 0.42); mean followup, 16.7 years

Standardized by age (in 5-year groups), sex, calendar year of first recorded admission, district of residence

Takes into account only those hospitalized with MS or identified at death Mild TBI may be underidentified inasmuch as all TBI identified during hospitalization No adjustments for other potential risk factors

Limitation is mixed age group; ages 0–65+ years included Strengths of study include head injury, MS diagnoses made independently, so recall bias avoided Geographically defined but otherwise unselected population Analysis of long- and short-term risk of MS after TBI