Background: Age has been shown to be a primary determinant of survival following isolated traumatic brain injury (TBI). We have previously reported that patients > or =65 years who survived mild TBI have decreased functional outcome at 6 months compared with younger patients. The purpose of this study was to further investigate the effect of age on outcome at 1 year in all patients surviving isolated TBI.
Methods: The Western Trauma Association multicenter prospective study included all patients sustaining isolated TBI defined as Abbreviated Injury Scale score for Head > or = 3 with an Abbreviated Injury Scale score in any other body area < or = 1. Outcome data included discharge disposition, Glasgow Outcome Scale score (1 = dead to 5= full recovery) and modified Functional Independence Measure (FIM) score measuring feeding, expression, and locomotion (1 = total dependence to 4 = total independence) for each component at discharge and 1 year.
Results: In all, 295 patients were enrolled with a follow-up of 82%, resulting in 241 study patients. An additional five patients died from non-TBI causes and were excluded. The mean and median times for the last follow-up in the 236 remaining patients were 307 and 357 days, respectively. Patients were divided into four age ranges: 18 to 29 years (n = 66), 30 to 44 years (n = 54), 45 to 59 years (n = 50), and > or =60 years (n = 65). More severe TBIs, as measured by admitting Glasgow Coma Scale (GCS), were observed in the youngest group compared with all others but there were no differences in mean GCS between the remaining three groups. There were no differences in neurosurgical intervention between the groups. Age was a major determinant in the outcome at discharge and last follow-up. Patients over 60 years discharged with a GOS < or =4 were less likely to improve at 1 year than all other groups (37% versus 63 to 85%; p < or = 0.05). Patients between 18 and 29 years of age had the lowest mean Glasgow Outcome Scale and discharge FIM scores, which correlated with the low admission GCS. Despite the increased severity of TBI, this group had the best FIM score at 1 year. In contrast, patients older than 60 years had the least improvement and had a significantly lower final FIM score at 1 year compared with all other groups.
Conclusion: Older patients following isolated TBI have poorer functional status at discharge and make less improvement at 1 year compared with all other patients. These worse outcomes occur despite what appears to be less severe TBI as measured by a higher GCS upon admission. Differences in outcome begin to appear even in patients between 45 and 59 years. Further investigations with more detailed outcome instruments are required to better understand the qualitative limitations of a patient's recovery and to devise strategies to maximize functional improvement following TBI. Age is an exceedingly important parameter affecting recovery from isolated TBI.