Descriptive Modeling of Longitudinal Outcome Measures in Traumatic Brain Injury: A National Institute on Disability and Rehabilitation Research Traumatic Brain Injury Model Systems Study

Predicting the Trajectory of Participation After Traumatic Brain Injury: A Longitudinal Analysis

OBJECTIVE

To identify factors that predict trajectories of participation over the first 5 years after moderate to severe traumatic brain injury (TBI).

SETTING

TBI Model System Programs.

PARTICIPANTS

Community-dwelling individuals with TBI, 16 years of age or older (n = 1947).

DESIGN

Secondary analysis of a prospective, nonrandomly sampled, longitudinal data registry.

MAIN MEASURES

Participation Assessment with Recombined Tools-Objective (PART-O).

RESULTS

Age at injury and FIM Motor score predicted trajectory of participation over the first 5 years after moderate to severe TBI. Older age predicted generally worse participation overall as well as progressively worsening participation over time. Higher FIM Motor raised the predicted participation values, although it reduced the rate of improvement in participation scores over time. FIM Cognitive scores, race, depression, years of education, and living setting did not predict trajectory but did significantly influence participation consistently at all time points.

CONCLUSION

The trajectories of participation over the first 5 years after TBI can be predicted by age at injury and FIM Motor scores. These findings may enhance the ability of rehabilitation professionals to identify individuals at risk for poor participation after TBI and develop targeted interventions for optimizing involvement in life activities.

Rehospitalization Over 10 Years Among Survivors of TBI: A National Institute on Disability, Independent Living, and Rehabilitation Research Traumatic Brain Injury Model Systems Study

OBJECTIVE

To describe the rates and causes for rehospitalization over 10 years after moderate-severe traumatic brain injury (TBI), and to characterize longitudinal trajectories of the probability of rehospitalization using generalized linear mixed models and individual growth curve models conditioned on factors that help explain individual variability in rehospitalization risk over time.

DESIGN

Secondary analysis of data from a multicenter longitudinal cohort study.

SETTING

Acute inpatient rehabilitation facilities and community follow-up.

PARTICIPANTS

Individuals 16 years and older with a primary diagnosis of TBI.

MAIN OUTCOME MEASURES

Rehospitalization (and reason for rehospitalization) as reported by participants or proxy during follow-up telephone interviews at 1, 2, 5, and 10 years postinjury.

RESULTS

The greatest number of rehospitalizations occurred in the first year postinjury (27.8% of the sample), and the rates of rehospitalization remained largely stable (22.1%-23.4%) at 2, 5, and 10 years. Reasons for rehospitalization varied over time: Orthopedic and reconstructive surgery rehospitalizations were most common in year 1, whereas general health maintenance was most common by year 2 with rates increasing at each follow-up. Longitudinal models indicate that multiple demographic and injury-related factors are associated with the probability of rehospitalization over time.

CONCLUSIONS

These findings can inform the content and timing of interventions to improve health and longevity after TBI.

The Feasibility of Telephone-Administered Cognitive Testing in Individuals 1 and 2 Years after Inpatient Rehabilitation for Traumatic Brain Injury

Traumatic brain injury (TBI) often results in cognitive impairment, and trajectories of cognitive functioning can vary tremendously over time across survivors. Traditional approaches to measuring cognitive performance require face-to-face administration of a battery of objective neuropsychological tests, which can be time- and labor-intensive. There are numerous clinical and research contexts in which in-person testing is undesirable or unfeasible, including clinical monitoring of older adults or individuals with disability for whom travel is challenging, and epidemiological studies of geographically dispersed participants. A telephone-based method for measuring cognition could conserve resources and improve efficiency. The objective of this study is to examine the feasibility and usefulness of the Brief Test of Adult Cognition by Telephone (BTACT) among individuals who are 1 and 2 years post-moderate-to-severe TBI. A total of 463 individuals participated in the study at Year 1 post-injury, and 386 participated at Year 2. The sample was mostly male (73%) and white (59%), with an average age of (mean ± standard deviation) 47.9 ± 20.9 years, and 73% experienced a duration of post-traumatic amnesia (PTA) greater than 7 days. A majority of participants were able to complete the BTACT subtests (61-69% and 56-64% for Years 1 and 2 respectively); score imputation for those unable to complete a test due to severity of cognitive impairment yields complete data for 74-79% of the sample. BTACT subtests showed expected changes between Years 1-2, and summary scores demonstrated expected associations with injury severity, employment status, and cognitive status as measured by the Functional Independence Measure. Results indicate it is feasible, efficient, and useful to measure cognition over the telephone among individuals with moderate-severe TBI.

Longitudinal Investigation of Rehospitalization Patterns in Spinal Cord Injury and Traumatic Brain Injury Among Medicare Beneficiaries

OBJECTIVES

To model 12-month rehospitalization risk among Medicare beneficiaries receiving inpatient rehabilitation for spinal cord injury (SCI) or traumatic brain injury (TBI) and to create 2 (SCI- and TBI-specific) interactive tools enabling users to generate monthly projected probabilities of rehospitalization on the basis of an individual patient's clinical profile at discharge from inpatient rehabilitation.

DESIGN

Secondary data analysis.

SETTING

Inpatient rehabilitation facilities.

PARTICIPANTS

Medicare beneficiaries receiving inpatient rehabilitation for SCI (n=2587) or TBI (n=10,864).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Monthly rehospitalization (yes/no) based on Medicare claims.

RESULTS

Results are summarized through computer-generated interactive tools, which plot individual level trajectories of rehospitalization probabilities over time. Factors associated with the probability of rehospitalization over time are also provided, with different combinations of these factors generating different individual level trajectories. Four case studies are presented to demonstrate the variability in individual risk trajectories. Monthly rehospitalization probabilities for the individual high-risk TBI and SCI cases declined from 33% to 15% and from 41% to 18%, respectively, over time, whereas the probabilities for the individual low-risk cases were much lower and stable over time: 5% to 2% and 6% to 2%, respectively.

CONCLUSIONS

Rehospitalization is an undesirable and multifaceted health outcome. Classifying patients into meaningful risk strata at different stages of their recovery is a positive step forward in anticipating and managing their unique health care needs over time.

Global Outcome Trajectories After TBI Among Survivors and Nonsurvivors: A National Institute on Disability and Rehabilitation Research Traumatic Brain Injury Model Systems Study

OBJECTIVE

To compare long-term functional outcome trajectories of individuals with traumatic brain injury (TBI) who survive with those who expire more than 5 years postinjury, using individual growth curve analysis.

DESIGN

Secondary analysis of data from a multicenter longitudinal cohort study.

SETTING

Acute inpatient rehabilitation facilities that are current or former TBI Model Systems.

PARTICIPANTS

Individuals 16 years and older with a primary diagnosis of TBI.

MAIN OUTCOME MEASURES

Glasgow Outcome Scale-Extended; Disability Rating Scale.

RESULTS

Individuals in the TBI Model Systems who expire several years after injury demonstrate worse functional status at baseline and a steeper rate of decline over time as measured by both the Glasgow Outcome Scale-Extended and the Disability Rating Scale. There was significant variability in each growth parameter (P < .05) for both instruments. A reduced model was built for each outcome, including all covariates that related significantly to the growth parameters. An interactive tool was created for each outcome to generate individual-level trajectories based on various combinations of covariate values.

CONCLUSION

Individuals with TBI who die several years after injury demonstrate functional trajectories that differ markedly from those of survivors. Opportunities should be sought for health management interventions to improve health and longevity after TBI.

A Multidimensional Rasch Analysis of the Functional Independence Measure Based on the National Institute on Disability, Independent Living, and Rehabilitation Research Traumatic Brain Injury Model Systems National Database

A number of studies have evaluated the psychometric properties of the Functional Independence Measure (FIM™) using Rasch analysis, although none has done so using the National Institute on Disability, Independent Living, and Rehabilitation Research Traumatic Brain Injury Model Systems National Database, a longitudinal database that captures demographic and outcome information on persons with moderate to severe traumatic brain injury across the United States. In the current study, we examine the psychometric properties of the FIM as represented by persons within this database and demonstrate that the FIM comprises three subscales representing cognitive, self-care, and mobility domains. These subscales were analyzed simultaneously using a multivariate Rasch model in combination with a time dependent concurrent calibration scheme with the goal of creating a raw score-to-logit transformation that can be used to improve the accuracy of parametric statistical analyses. The bowel and bladder function items were removed because of misfit with the motor and cognitive items. Some motor items exhibited step disorder, which was addressed by collapsing Categories 1-3 for Toileting, Stairs, Locomotion, Tub/Shower Transfers; Categories 1 and 2 for Toilet and Bed Transfers; and Categories 2 and 3 for Grooming. The strong correlations (r = 0.82-0.96) among the three subscales suggest they should be modeled together. Coefficient alpha of 0.98 indicates high internal consistency. Keyform maps are provided to enhance clinical interpretation and application of study results.

Ten-Year Employment Patterns of Working Age Individuals After Moderate to Severe Traumatic Brain Injury: A National Institute on Disability and Rehabilitation Research Traumatic Brain Injury Model Systems Study

OBJECTIVE

To describe the 10-year patterns of employment for individuals of working age discharged from a Traumatic Brain Injury Model Systems (TBIMS) center between 1989 and 2009.

DESIGN

Secondary data analysis.

SETTING

Inpatient rehabilitation centers.

PARTICIPANTS

Patients aged 16 to 55 years (N=3618) who were not retired at injury, received inpatient rehabilitation at a TBIMS center, were discharged alive between 1989 and 2009, and had at least 3 completed follow-up interviews at postinjury years 1, 2, 5, and 10.

INTERVENTIONS

Not applicable.

MAIN OUTCOMES MEASURE

Employment.

RESULTS

Patterns of employment were generated using a generalized linear mixed model, where these patterns were transformed into temporal trajectories of probability of employment via random effects modeling. Covariates demonstrating significant relations to growth parameters that govern the trajectory patterns were similar to those noted in previous cross-sectional research and included age, sex, race/ethnicity, education, preinjury substance misuse, preinjury vocational status, and days of posttraumatic amnesia. The calendar year in which the injury occurred also greatly influenced trajectories. An interactive tool was developed to provide visualization of all postemployment trajectories, with many showing decreasing probabilities of employment between 5 and 10 years postinjury.

CONCLUSIONS

These results highlight that postinjury employment after moderate to severe traumatic brain injury (TBI) is a dynamic process, with varied patterns of employment for individuals with specific characteristics. The overall decline in trajectories of probability of employment between 5 and 10 years postinjury suggests that moderate to severe TBI may have unfavorable chronic effects and that employment outcome is highly influenced by national labor market forces. Additional research targeting the underlying drivers of the decline between 5 and 10 years postinjury is recommended, as are interventions that target influencing factors.

An introduction to analyzing dichotomous outcomes in a longitudinal setting: a NIDRR traumatic brain injury model systems communication

An untapped wealth of temporal information is captured within the Traumatic Brain Injury Model Systems National Database. Utilization of appropriate longitudinal analyses can provide an avenue toward unlocking the value of this information. This article highlights 2 statistical methods used for assessing change over time when examination of noncontinuous outcomes is of interest where this article focuses on investigation of dichotomous responses. Specifically, the intent of this article is to familiarize the rehabilitation community with the application of generalized estimating equations and generalized linear mixed models as used in longitudinal studies. An introduction to each method is provided where similarities and differences between the 2 are discussed. In addition, to reinforce the ideas and concepts embodied in each approach, we highlight each method, using examples based on data from the Rocky Mountain Regional Brain Injury System.

Hospital-acquired pneumonia is an independent predictor of poor global outcome in severe traumatic brain injury up to 5 years after discharge

BACKGROUND

Long-term outcomes following traumatic brain injury (TBI) correlate with initial head injury severity and other acute factors. Hospital-acquired pneumonia (HAP) is a common complication in TBI. Limited information exists regarding the significance of infectious complications on long-term outcomes after TBI. We sought to characterize risks associated with HAP on outcomes 5 years after TBI.

METHODS

This study involved data from the merger of an institutional trauma registry and the Traumatic Brain Injury Model Systems outcome data. Individuals with severe head injuries (Abbreviated Injury Scale [AIS] score ≥ 4) who survived to rehabilitation were analyzed. Primary outcome was Glasgow Outcome Scale-Extended (GOSE) at 1, 2, and 5 years. GOSE was dichotomized into low (GOSE score < 6) and high (GOSE score ≥ 6). Logistic regression was used to determine adjusted odds of low GOSE score associated with HAP after controlling for age, sex, head and overall injury severity, cranial surgery, Glasgow Coma Scale (GCS) score, ventilation days, and other important confounders. A general estimating equation model was used to analyze all outcome observations simultaneously while controlling for within-patient correlation.

RESULTS

A total of 141 individuals met inclusion criteria, with a 30% incidence of HAP. Individuals with and without HAP had similar demographic profiles, presenting vitals, head injury severity, and prevalence of cranial surgery. Individuals with HAP had lower presenting GCS score. Logistic regression demonstrated that HAP was independently associated with low GOSE scores at follow-up (1 year: odds ratio [OR], 6.39; 95% confidence interval [CI], 1.76-23.14; p = 0.005) (2 years: OR, 7.30; 95% CI, 1.87-27.89; p = 0.004) (5-years: OR, 6.89; 95% CI, 1.42-33.39; p = 0.017). Stratifying by GCS score of 8 or lower and early intubation, HAP remained a significant independent predictor of low GOSE score in all strata. In the general estimating equation model, HAP continued to be an independent predictor of low GOSE score (OR, 4.59; 95% CI, 1.82-11.60; p = 0.001).

CONCLUSION

HAP is independently associated with poor outcomes in severe TBI extending 5 years after injury. This suggests that precautions should be taken to reduce the risk of HAP in individuals with severe TBI.

LEVEL OF EVIDENCE

Prognostic study, level III.

Using Rasch motor FIM individual growth curves to inform clinical decisions for persons with paraplegia

STUDY DESIGN

A longitudinal retrospective study.

OBJECTIVE

To better understand individual-level temporal change in functional status for participants with paraplegia in the National Spinal Cord Injury Database (NSCID), as measured by Rasch Transformed Motor Functional Indepedence Measure (FIM) scores.

SETTING

Multicenter/Multistate longitudinal study across the United States.

METHODS

Non-linear random effects modeling, that is, individual growth curve analysis of retrospective data obtained from the National Institute on Disability and Rehabilitation Research (NIDRR) NSCID.

RESULTS

We generated non-linear individual level trajectories of recovery for Rasch Transformed Motor FIM scores that rise rapidly from inpatient rehabilitation admission to a plateau. Trajectories are based on relationships between growth parameters and patient and injury factors: race, gender, level of education at admission, age at injury, neurological level at discharge, American Spinal Injury Association Impairment Scale (AIS) at discharge, days from injury to first system inpatient rehabilitation admission, rehabilitation length of stay, marital status and etiology. On the basis of study results, an interactive tool was developed to represent individual level longitudinal outcomes as trajectories based upon an individual's given baseline characteristics, that is, information supplied by the covariates and provides a robust description of temporal change for those with paraplegia within the NSCID.

CONCLUSIONS

This methodology allows researchers and clinicians to generate and better understand patient-specific trajectories through the use of an automated interactive tool where a nearly countless number of longitudinal paths of recovery can be explored. Projected trajectories holds promise in facilitating planning for inpatient and outpatient services, which could positively impact long term outcomes.

Longitudinal description of the glasgow outcome scale-extended for individuals in the traumatic brain injury model systems national database: a National Institute on Disability and Rehabilitation Research traumatic brain injury model systems study

OBJECTIVE

To comprehensively describe the temporal patterns of global outcome after traumatic brain injury (TBI) in the Traumatic Brain Injury Model Systems National Database (TBIMS NDB).

DESIGN

Longitudinal prospective cohort study.

SETTING

TBI Model Systems centers.

PARTICIPANTS

Patients (N=3870) ≥16 years of age with moderate or severe TBI enrolled in the TBIMS NDB.

INTERVENTIONS

None.

MAIN OUTCOME MEASURE

Glasgow Outcome Scale-Extended (GOS-E).

RESULTS

The trajectory of the GOS-E scores is best described with a model of quadratic change, in which scores initially increase and peak approximately 10 years after the first GOS-E assessment, and then decrease. Change occurs most rapidly in the initial and final years of the timeline. There was significant variability in each growth parameter (P<.05). A reduced multilevel model was built, including all covariates (age at first GOS-E assessment, FIM, race, sex, rehabilitation length of stay) that related significantly to the growth parameters. An interactive tool was created to generate individual level trajectories based on various combinations of covariate values. Results provide an individual level account of the chronological progression of TBI outcomes, as measured by the GOS-E.

CONCLUSIONS

Individual growth curve analysis is a statistically rigorous approach to describe temporal change with respect to the GOS-E at the individual level for participants within the TBIMS NDB. Results indicated that, for individuals in the TBIMS NDB as a group, functional status as measured by the GOS-E initially improves, plateaus, and then begins to decline. Factors such as age at first GOS-E assessment, race, FIM score at rehabilitation admission, and rehabilitation length of stay were found to influence baseline GOS-E scores, as well as the rate and extent of both improvement and decline over time. Additional research may be required to determine the generalizability of these findings and the usefulness of this tool for clinical applications.

Longitudinal description of the disability rating scale for individuals in the National Institute on Disability and Rehabilitation Research traumatic brain injury model systems national database

OBJECTIVE

To develop a detailed understanding of temporal change (ie, estimated trajectories) at the individual level as measured by the Disability Rating Scale (DRS).

DESIGN

Individual growth curve (IGC) analysis of retrospective data obtained from the National Institute on Disability and Rehabilitation Research Traumatic Brain Injury (TBI) Model Systems National Database.

SETTING

Multicenter longitudinal database study.

PARTICIPANTS

Individuals with TBI (N=8816) participating in the TBI Model Systems National Database project.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE DRS RESULTS

The negative exponential consisting of 3 growth parameters (pseudointercept, asymptote, rate) was successfully used to predict trajectory of recovery on the DRS qualified by the following covariates: race, sex, level of education and age at admission, rehabilitation length of stay, and cognitive and motor FIM scores at rehabilitation admission. Based on these results, an interactive tool was developed to allow prediction of the trajectory of recovery for individuals and subgroups with specified characteristics on the selected covariates.

CONCLUSIONS

With the use of IGC analysis, the longitudinal trajectory of recovery on the DRS for individuals sharing common characteristics and traits can be described. This methodology allows researchers and clinicians to predict numerous individual-level trajectories through use of a web-based computer automated interactive tool.