Head Injuries Decrease Long-Term Survival Time

Head injuries decreased long-term survival time in a dose-dependent manner, longitudinal data showed.

All-cause mortality was twice as high for adults who had sustained a head injury earlier in life (HR 1.99, 95% CI 1.88-2.11) compared with those who had no head injury, reported Holly Elser, MD, PhD, of the University of Pennsylvania in Philadelphia, and co-authors.

Both the frequency of head hits and the severity of impact upped mortality risk, Elser and colleagues wrote in JAMA Neurology.

For adults with one head injury, mortality HR was 1.66 (95% CI 1.56-1.77); for those with two or more head injuries, HR was 2.11 (95% CI 1.89-2.37). Adults with a mild head injury had a mortality HR of 2.16 (95% CI 2.01-2.31), while those with a moderate, severe, or penetrating head injury had an HR of 2.87 (95% CI 2.55-3.22).

"Past research tells us that the risk of death is increased immediately following head injury in the hospital setting, but there is limited research that examines the long-term mortality implications of head injury, particularly among community-dwelling adults," Elser told MedPage Today.

"This study examines the association between head injury and death from all causes in more than 13,000 community-dwelling adults followed from 1987 through 2019," she continued. "Overall, these results underscore the importance of public health interventions to prevent head injuries and clinical interventions to mitigate their effects when they happen."

Traumatic brain injury (TBI) has two distinct phases, Elser and colleagues observed. Primary injury includes tissue distortion and destruction directly from the forces of the initial injury. Secondary injury occurs over time and may include blood-brain barrier dysfunction, edema, ischemia, or intracranial hypertension.

The researchers studied 13,037 participants in the prospective Atherosclerosis Risk in Communities Study (ARIC) study, an ongoing study in four U.S. communities. The median baseline age was 54, and the median time from enrollment to first head injury was 17 years. Overall, 72.1% of participants were white, 27.9% were Black, and 57.7% were women.

Head injury with or without loss of consciousness was based on self-report and data from emergency department visits and inpatient hospitalizations. Mortality information came from state vital records, death certificates, and the National Death Index.

A total of 2,402 participants (18.4%) had at least one head injury and 512 had two or more head injuries over a median 27 years of follow-up. Most participants (1,862 people) had head injuries identified from hospital diagnoses alone; 299 had injuries identified by self-report alone, and 241 had injuries from both hospital diagnoses and self-report.

During the study period, 7,353 participants (56.4%) died, of whom 1,552 (64.6%) were people with head injury. Median time from head injury to death was 4.7 years.

Subgroup analyses showed no evidence of a statistical interaction by sex or race, but results were attenuated for people age 54 or older at baseline. The most common causes of death were neoplasm, cardiovascular disease, and neurologic disorders.

"A greater proportion of deaths among those with head injury versus those without head injury were due to neurologic causes -- 62.2% vs 51.4%," Elser said. "Further, a greater proportion of deaths among those with head injury versus those without were due to neurodegenerative disorders -- 14.2% vs 6.6%."

The study findings could reflect that individuals who experienced head injury have increased mortality risk at baseline, that head injury causes an increase in mortality risk, or a combination of the two, Elser and co-authors acknowledged. Results might not apply to other racial or age groups, the team noted. In addition, the researchers could not distinguish between associations of primary versus secondary phases of head injury with mortality risk.

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