Objective: To put forth an analytic strategy for identifying participant and nonparticipant
factors predictive of attrition and wave nonresponse in the Traumatic Brain Injury
Model Systems (TBIMS) program, a multi-site, longitudinal study of outcomes in individuals
with traumatic brain injury (TBI). Preliminary findings will also be presented and
discussed. Design: Retrospective analysis of TBIMS data collected from 1987 through 2009. Setting: Data were gathered through semi-structured interviews conducted in-person or via
telephone by TBIMS staff. Participants: Individuals 16 years or older with TBI ranging from moderate to severe, hospitalized
within 72 hours of injury, and given acute care and inpatient rehabilitation in a
model system hospital (N=9844). Interventions: Not applicable. Main Outcome Measures: For demographic variables (eg, age), appropriate items from TBIMS Form I assessment.
For psychosocial participant variables (eg, employment status) and nonparticipant
factors (eg, site), appropriate items from TBIMS Form II assessment. Results: The relation between single variables and attrition will be determined using chi-square
tests for categorical variables and t tests for continuous variables. Selected variables will include those previously
associated with attrition in TBIMS (eg, socioeconomic status) and in longitudinal
studies of other populations (eg, functional status). Exploratory analysis of participant
factors (eg, community integration) and nonparticipant factors (eg, recruitment benchmark
changes) will also be conducted. Variables significantly associated with attrition
will then be included in a logistic regression to determine the strongest predictors
and begin developing a predictive model. A similar set of analyses will investigate
factors related to wave nonresponse. Conclusions: Determining the constellation of participant and nonparticipant factors associated
with attrition and wave-nonresponse is a necessary first step toward improving the
validity of longitudinal research results regarding TBI outcomes. Specifically, such
information could help identify participants at high risk of attrition who require
additional investigator effort for retention or provide empirical bases for weighting
cases in future statistical analyses.
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Disclosure: None declared.
© 2010 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.