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Randomized Controlled Trial
. 2019 Mar;25(3):293-301.
doi: 10.1017/S1355617718001078.

Longitudinal Changes in Disability Rating Scale Scores: A Secondary Analysis Among Patients With Severe TBI Enrolled in the Epo Clinical Trial

Julia S Benoit  1 , H Julia Hannay  2 , Jose-Miguel Yamal  3 , David J Francis  2 , Imoigele Aisiku  4 , Claudia Robertson  5
Affiliations
Randomized Controlled Trial

Longitudinal Changes in Disability Rating Scale Scores: A Secondary Analysis Among Patients With Severe TBI Enrolled in the Epo Clinical Trial

Julia S Benoit et al. J Int Neuropsychol Soc. 2019 Mar.

Abstract

Objectives: Long-term neurological response to treatment after a severe traumatic brain injury (sTBI) is a dynamic process. Failure to capture individual heterogeneity in recovery may impact findings from single endpoint sTBI randomized controlled trials (RCT). The present study re-examined the efficacy of erythropoietin (Epo) and transfusion thresholds through longitudinal modeling of sTBI recovery as measured by the Disability Rating Scale (DRS). This study complements the report of primary outcomes in the Epo sTBI RCT, which failed to detect significant effects of acute treatment at 6 months post-injury.

Methods: We implemented mixed effects models to characterize the recovery time-course and to examine treatment efficacy as a function of time post-injury and injury severity.

Results: The inter-quartile range (25th-75th percentile) of DRS scores was 20-28 at week1; 8-24 at week 4; and 3-17 at 6 months. TBI severity group was found to significantly interact with Epo randomization group on mean DRS recovery curves. No significant differences in DRS recovery were found in transfusion threshold groups.

Conclusions: This study demonstrated the value of taking a comprehensive view of recovery from sTBI in the Epo RCT as a temporally dynamic process that is shaped by both treatment and injury severity, and highlights the importance of the timing of primary outcome measurement. Effects of Epo treatment varied as a function of injury severity and time. Future studies are warranted to understand the possible moderating influence of injury severity on treatment effects pertaining to sTBI recovery. (JINS, 2019, 25, 293-301).

Keywords: DRS; Functional outcome; Injury severity; Long-term functional recovery; Longitudinal data analysis; Neurotrauma; Randomized clinical trial; Treatment profiles.

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Conflict of interest statement

Author Disclosure Statement: No competing financial interests exist.

Figures

Figure 1.
Figure 1.
Individual trajectories of Disability Rating Scale (DRS) scores across patients in the EPO randomization trial (n=193). *Thick black line indicates the average change trajectory for the entire sample.
Figure 2.
Figure 2.
Inverted Kaplan Meier Curves of mortality rates by injury severity group.
Figure 3.
Figure 3.
Estimated recovery curves of DRS scores by Epo randomization group and sTBI group, among individuals from the EPO randomization trial. This figure represents the DRS cubic change based on the growth curve parameter estimates (Supplemental Table S1). *Time is measured in days after injury.
Figure 4.
Figure 4.
Estimated recovery curves of DRS scores by transfusion threshold randomization group (TT) and TBI injury severity groups from the Epo randomization trial. This figure represents the DRS score cubic change based on the growth curve parameter estimates (Supplemental Table S1). *Time is measured in days after injury.
See this image and copyright information in PMC

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