Prevalence of Disability Associated With Head Injury With Loss of Consciousness in Adults in the United States: A Population-Based Study

Abstract

Objective: To provide nationally representative prevalence estimates of disability associated with prior head injury with loss of consciousness in the United States and to examine associations between prior head injury and disability.

Methods: This was a cross-sectional analysis of 7,390 participants ≥40 years of age in the 2011-2014 National Health and Nutrition Examination Surveys (NHANES). Head injury with loss of consciousness was assessed by self-report. Domains of disability were assessed with a standardized structured questionnaire and measured grip strength. Logistic and linear regression models adjusted for demographic, socioeconomic/behavioral, and medical comorbidity variables were used. Multiple imputation was used to account for missing covariate data.

Results: Mean age of participants was 58 years; 53% were female; 71% were non-Hispanic White; and 16% had a history of head injury with loss of consciousness. Overall, participants with a history of head injury had higher prevalence of disability in at least 1 domain of functioning compared to individuals without head injury (47.4% vs 38.6%, p < 0.001), with the highest prevalence of disability in the domains of mobility and work productivity. In fully adjusted models, head injury was significantly positively associated with disability in all domains assessed on the standardized questionnaire (all p < 0.05). Participants with head injury had greater grip strength (all p < 0.05).

Conclusions: We found that 47.4% of individuals ≥40 years of age in the United States with a history of head injury are living with disability in at least 1 domain of functioning, corresponding to 11.4 million affected individuals. This significant burden of disability suggests that efforts are needed to improve functioning among individuals with head injury.

Figure 1. Participant Inclusion/Exclusion Diagram, NHANES 2011–2014

NHANES = National Health and Nutrition Examination Surveys. *Head injury with loss of consciousness question was a part of the taste and smell questionnaire, which was administered to all participants ≥40 years of age during the 2011–2012 and 2013–2014 surveys. **The following covariates contained missing data that were accounted for with multiple imputation using chained equations in all adjusted analyses: education (n = 7), family income to poverty ratio (n = 663), moderate/vigorous work or recreational activity (n = 2), alcohol consumption (n = 961), hypertension (n = 314), history of cardiovascular disease (n = 3), history of stroke (n = 8), and depression (n = 986).

Figure 2. Age-Adjusted Prevalence (95% confidence interval) of Disability by History of Head Injury With Loss of Consciousness

(A) Physical functioning domains. (B) Functional limitations domains. *p < 0.01 comparing no head injury to history of head injury. **p < 0.001 comparing no head injury to history of head injury.