In a recent study published in JAMA Network Open, researchers in the United States (US) investigated functional recovery, symptom burden, and quality of life (QoL) over five years of traumatic brain injury (TBI).
TBI patients usually recover most swiftly during the initial three to six months of injury. Most studies terminate follow-up by six months, and therefore, data on the natural long-term course of TBI are limited. Contrastingly, studies have reported on dynamic TBI recovery, continuing over the years.
The multicenter transforming research and clinical knowledge in TBI (TRACK-TBI) study reported that most of the level 1.0 trauma care patients with mild TBI (mTBI) experience symptoms and trauma-associated difficulties in performing routine activities at one-year post-injury.
In the TRACK-TBI study, moderate-severe TBI (msTBI) patients exhibited varied TBI outcomes, often attaining functional independence and resuming work, although complete functional recovery was rare.
Unlike the dose-response relationship between TBI severity and functional outcomes, persistently elevated symptom burden was observed among all the level 1.0 trauma care patients with weak and, at times, contradictory relationships with the severity of TBI. Data on long-term outcomes of TBI could aid in developing improved assessments and rehabilitation care services.
About the study
The present study investigated the natural course of functional independence, symptom burden, and QoL outcomes after one to five years of TBI among mTBI and msTBI patients.
The study comprised TBI patients aged ≥17.0 years across 18 level 1.0 trauma care centers in the US, enrolled in the parent TRACK-TBI study between 26 February 2014 and 27 July 2018, within 1.0 days of TBI. The patients were followed up for five years following injury. All included individuals had known admission Glasgow coma scale (GCS) scores and no known deaths within a year of TBI. Data analysis was performed in January 2023.
The study groups comprised mTBI patients, msTBI patients, and orthopaedic traumatic control individuals (OTC). The prime study outcomes were functional independence, a lower burden of TBI-associated symptoms, and improved QoL.
TBI-associated deaths were assessed as a secondary outcome. Functional independence and complete functional recovery were assessed using the Glasgow outcome scale-extended (GOSE).
TBI-associated symptom burden was assessed using the Rivermead post-concussion symptoms questionnaire, and QoL was assessed using the QoL after brain injury-overall scale. Multivariable-type and mixed-effects-type regression modeling analyses were performed to calculate the odds ratios (OR). Inverse probability weighting was performed for the primary analyses.
Individuals who were pregnant, held in legal custody, had an unmanageable physical injury, suffered from neurological or mental health disorders, and could not speak English (except those who spoke Spanish) were excluded from the analysis.
Eligibility criteria for the parent study comprised individuals presenting within a day post-injury to level I trauma care centers with clinically suspected TBI, with objective findings of TBI on head computed tomography (CT) scans, or altered consciousness, according to the TBI definition provided by the American congress of rehabilitation medicine.
In total, 1,196 individuals with TBI were analyzed, having a mean age of 41 years, and among whom, 65% (n=781) were men, 13% (n=158) were Black, and 81% (n=965) were White. Among the participants, 859, 188, and 152 individuals belonged to the mTBI, msTBI, and OTC control groups, respectively. The proportion of individuals with acute intracranial findings on admission head CT scans was mTBI, and msTBI groups were 39% (n=322) and 91% (n=162), respectively.
The mTBI patients and OTC controls showed high functional independence levels of 98.0% to 100.0%, which remained stable over time. While the probability of independence was lesser for msTBI patients, 72% were functionally independent within a year, with an increase in proportion with time (80.0% within five years; annual independence: OR values for msTBI and mTBI were 1.3 and 0.8, respectively). Concerning other TBI outcomes, the differences among groups at 12 months remained stable with time.
The probability of complete recovery of function was lesser for individuals with mTBI versus OTC (odds ratio 0.4) and lesser for msTBI. The probability of improved TBI-associated symptom outcomes and QoL were comparable for the TBI groups and lesser compared to that for controls. Mortality between one and five years was greater among msTBI patients than mTBI and OTC, with rates of 5.5%, 1.50%, and 0.7%, respectively.
Secondary analysis stratifying mTBI patients by the presence or absence of positive CT findings showed no statistically significant differences between the groups. The probability of functional independence was lower among older individuals (OR per 10 years of age, 0.7). The probability of functional independence was greater among those without non-Medicaid insurance (versus none or Medicaid insurance OR 2.4).
The probabilities of complete functional recovery and lowered symptom burden were lower among older individuals, women, individuals with none or Medicaid insurance, lower level of education, and previous history of TBI.
Overall, the study findings showed that msTBI was related to greater mortality among TBI patients who followed for five years post-injury. Nevertheless, msTBI patients showed improved functional independence from one to five years, and mTBI patients had worse outcomes than control individuals.
The study findings, coupled with the persistently greater rates of unfavorable outcomes among mTBI patients versus controls, indicate the need for improved assessment and rehabilitation of TBI and further research to improve understanding of long-term TBI outcomes and recovery.