Optimizing Concussion Care Seeking: The Influence of Previous Concussion Diagnosis Status on Baseline Assessment Outcomes

Abstract

Background: The prevalence of unreported concussions is high, and undiagnosed concussions can lead to worse postconcussion outcomes. It is not clear how those with a history of undiagnosed concussion perform on subsequent standard concussion baseline assessments. Purpose: To determine if previous concussion diagnosis status was associated with outcomes on the standard baseline concussion assessment battery. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Concussion Assessment, Research, and Education (CARE) Consortium participants (N = 29,934) self-reported concussion history with diagnosis status and completed standard baseline concussion assessments, including assessments for symptoms, mental status, balance, and neurocognition. Multiple linear regression models were used to estimate mean differences and 95% CIs among concussion history groups (no concussion history [n = 23,037; 77.0%], all previous concussions diagnosed [n = 5315; 17.8%], ≥1 previous concussions undiagnosed [n = 1582; 5.3%]) at baseline for all outcomes except symptom severity and Brief Symptom Inventory–18 (BSI-18) score, in which negative binomial models were used to calculate incidence rate ratios (IRRs). All models were adjusted for sex, race, ethnicity, sport contact level, and concussion count. Mean differences with 95% CIs excluding 0.00 and at least a small effect size (≥0.20), and those IRRs with 95% CIs excluding 1.00 and at least a small association (IRR, ≥1.10) were considered significant. Results: The ≥1 previous concussions undiagnosed group reported significantly greater symptom severity scores (IRR, ≥1.38) and BSI-18 (IRR, ≥1.31) scores relative to the no concussion history and all previous concussions diagnosed groups. The ≥1 previous concussions undiagnosed group performed significantly worse on 6 neurocognitive assessments while performing better on only 2 compared with the no concussion history and all previous concussions diagnosed groups. There were no between-group differences on mental status or balance assessments. Conclusion: An undiagnosed concussion history was associated with worse clinical indicators at future baseline assessments. Individuals reporting ≥1 previous undiagnosed concussions exhibited worse baseline clinical indicators. This may suggest that concussion-related harm may be exacerbated when injuries are not diagnosed.

Optimizing Concussion Care Seeking: Connecting Care-Seeking Behaviors and Neurophysiological States Through Blood Biomarkers

“…However, the theoretical consistency of the previous clinical findings and our current neurobiological findings provides confidence in the posited mechanism and suggests the utility of further investigation in larger and more adequately powered samples. These biomarker patterns have consistencies with our previous analyses using clinical outcomes, which illustrate that previous undiagnosed concussions and delayed reporting 44 were associated with higher subsequent symptom levels.…”

“…46 Together, these results suggest that delayed removal from activity or previous undiagnosed concussions have differential neurobiological consequences, in addition to the already observed clinical consequences. 3,37,44,62 All differences discerned with these biomarkers emerged after concussion, with no differences detected at baseline in any measure. NF-L levels were elevated for the 1 undiagnosed concussion group in the postinjury phase and remained elevated at the asymptomatic time point.…”

“…A previous analysis of the clinical data with much greater statistical power showed no correlation between these 2 statistical models of different aspects of past and current care seeking. 44 For dependent variables, we compared fluid biomarker recovery curves for GFAP, NF-L, tau, and UCH-L1 among those who sustained a concussion within the CARE Consortium data capture period, including the following time points: (1) baseline, (2) 24 to 48 hours post-injury, (3) asymptomatic, and (4) 7 days after return to activity. We excluded the 0-to 6-hour time point because this time point was often missed, especially in cases of delayed care seeking.…”

“…Blood biomarker data are difficult to collect, resulting in relatively fewer data points than in our clinical analyses of the same data. 44 This may have affected our statistical power and ability to detect significant differences. We also did not show baseline differences in any biomarker measures as we did for clinical measures.…”

“…We also did not show baseline differences in any biomarker measures as we did for clinical measures. 44 There is a relatively long causal chain between care seeking and blood biomarkers, introducing difficulty in ascribing direction of causality between biological states and care seeking. Similarly, direction of causality (do elevated biomarkers cause or merely reflect more symptomatic recoveries?)…”