Natural Progression of Routine Laboratory Markers following Spinal Trauma: A Longitudinal, Multi-Cohort Study

Objective To track and quantify the natural course of hematological markers over the first year following spinal cord injury. Methods Data on hematological markers, demographics, and injury characteristics were extracted from medical records of a clinical trial (Sygen) and an ongoing observational cohort study (Murnau Study). The primary outcomes were concentration/levels/amount of commonly collected hematological markers at multiple time-points. Two-way ANOVA and mixed-effects regression techniques were used to account for the longitudinal data and adjust for potential confounders. Trajectories of hematological markers contained in both data sources were compared using the slope of progression. Results At baseline (≤ 2 weeks post-injury), most hematological markers were at pathological levels, but returned to normal values over the course of six to twelve months post-injury. The baseline levels and longitudinal trajectories were dependent on injury severity. More complete injuries were associated with more pathological values (e.g. hematocrit, ANOVA test; Chisq = 77.10, df = 3, adjusted p-value<0.001, and Chisq = 94.67, df = 3, adjusted p-value<0.001, in the Sygen and Murnau studies, respectively). Comparing the two databases revealed some differences in the hematological markers, which are likely attributable to differences in study design, sample size, and standard of care. Conclusions Due to trauma-induced physiological perturbations, hematological markers undergo marked changes over the course of recovery, from initial pathological levels that normalize within a year. The findings from this study are important as they provide a benchmark for clinical decision making and prospective clinical trials. All results can be interactively explored on the Haemosurveillance website (). Code availability ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study was funded by research grants from the Swiss National Science Foundation (Ambizione Grant #PZ00P3\_186101, Jutzeler) and Wings for Life Research Foundation (#2017\_044, Jutzeler and Kramer). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study was performed in accordance with the Declaration of Helsinki. Approval for the secondary analysis of the Sygen trial was received by an institutional ethical standards committee on human experimentation at the University of British Columbia. The original Sygen clinical trial (results published elsewhere) also received ethical approval, but was conducted before clinical trials were required to be registered. The data received from the original clinical trial were de-identified. The Murnau study was approved by the Bavarian Medical Chamber [#2018-077]. All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes Anonymized data used in this study will be made available upon request to the corresponding author and in compliance with the General Data Protection Regulation (EU GDPR). The code describing the analysis can be accessed on our GitHub repository (https://github.com/jutzca/Systemic-effects-of-Spinal-Cord-Injury).