Heterogeneity in Temporal Ordering of Depression and Participation After Traumatic Brain Injury

Abstract Objectives To examine heterogeneity in the temporal patterns of depression and participation over the first two years post-TBI. Design Observational prospective longitudinal study. Setting Inpatient rehabilitation centers, with 1- and 2-year follow-up conducted primarily by telephone. Participants Persons with TBI (N=2307) enrolled in the Traumatic Brain Injury Model Systems database, followed at 1 and 2 years postinjury. Interventions Not applicable. Main Outcome Measure Patient Health Questionnaire-9 (PHQ9) and Participation Assessment with Recombined Tools-Objective (PART-O) Results Using latent class modeling we examined heterogeneity in the longitudinal relationship between PHQ9 and PART-O. The identified 6 classes were most distinct in terms of 1) level of PHQ9 score and 2) association between the year 1 PART-O score and year 2 PHQ9 score. For most participants, PART-O at year 1 predicted PHQ9 at year 2 more than the reverse. However, there was a subgroup of participants that demonstrated the reverse pattern, PHQ9 predicting later PAR-O, who were on average, older and in the “other” employment category. Conclusions Results suggest that links between participation and depression are stronger for some people living with TBI than for others, and that variation in the temporal sequencing of these two constructs is associated with demographic characteristics. These findings illustrate the value in accounting for population heterogeneity when evaluating temporal among outcome domains.