Additional file 2: Figure S1. Annual number of patients enrolled in the EMSCI study. On average 242 patients were included in EMSCI per year across all participating centers. In 2001, EMSCI was founded and only three centers were recruiting patients. Figure S2. Ratio of female and male EMSCI patients with traumatic spinal cord injury between 2001 and 2019. (A) The sex ratio remained constant over time in para- and tetraplegic patients. (B) Similarly, no change over time could be observed when stratifying patients according to injury severity, i.e., AIS grades. Figure S3. Overall annual distribution of age at injury stratified by sex. Over the last two decades, there was a shift in age at injury for both, male and female individuals with spinal cord injury. In comparison to early 2000’s, which were characterized by a unimodal distribution, the proportion of elderly people sustaining a traumatic spinal cord injury increased significantly. Figure S4. Age at injury of EMSCI patients stratified by injury level and severity. Independent of (A) level of injury and (B) injury severity, there was a change in age at injury over the last decade. While in 2001 predominantly young individuals sustained a traumatic spinal cord injury, the proportion of elderly patient significantly increased with time. Figure S5. Proportional distribution of (A) injury severity and (B) injury level of EMSCI patients who sustained a traumatic spinal cord injury between 2001 and 2019. The injury severity remained constant over time in the paraplegic and tetraplegic cohort. More pronounced fluctuations were observed in the injury levels across different AIS grades. Figure S6. Trend estimates of distribution of injury severity in different age groups for male and female EMSCI patients. Positive estimates indicate in an increase in proportion of a specific AIS grade over timeframe between 2001 and 2019, while negative estimates indicate a decrease. In the age groups below 70 years, the proportion of AIS grades remained constant as opposed to the over 70 years of age group that is characterized by a decrease in severe injuries. In the female population, the heterogeneity in terms of injury severities is greater. This has to be interpreted with caution as the number of female patients is relatively small. Figure S7. Sensorimotor recovery between 2001 and 2019. The recovery trajectories of (A) lower and (B) upper extremity, as well as the (C) total motor score, and (D) total sensory score were comparable across the study duration. Less severe injuries (i.e., AIS-C and AIS-D) were associated with a higher sensorimotor recovery. The solid lines represent the fitted models and the shaded areas the standard error. Note: The total sensory score is computed as the sum of the total pin prick score and total light touch score. Figure S8. Time-series of neurological and functional recovery throughout the surveillance period. The sensorimotor recovery, measured as (A) total motor score, (B) and total sensory score, is characterized by an improvement over the course of one year (i.e., transition from the very acute to chronic phase). (C) Similar pattern and rate of recovery can be observed for the functional outcome, measured by the SCIM2/3. However, neither the pattern nor the degree of neurological and functional recovery changed between 2001 and 2019. In other words, the degree a person with spinal cord injury spontaneously recovers sensory and motor function within one-year post-injury is the same now as it was two decades ago. The solid lines represent the fitted models and the shaded areas the standard error. Figure S9. Walking function recovery between 2001 and 2019. The recovery trajectories of the (A) walking endurance, and (B) walking cadence remained comparable throughout the surveillance period. Less severe injuries (i.e., AIS-C and AIS-D) were associated with more functional recovery, including walking. The solid lines represent the fitted models and the shaded areas the standard error. Figure S10. Time-series of recovery of walking function throughout the surveillance period. Dependent on the injury severity, walking function, measured by (A) WISCI, (B) 6-minute walking test, and (C) 10m walking test spontaneously recovers, in part, during the transition from the acute to the chronic phase of injury. Importantly, the increase in different aspects of the walking function, such as endurance (6-minute walking test) and cadence (10m walking test), within one-year post-injury remained comparable throughout the surveillance period. The solid lines represent the fitted models and the shaded areas the standard error. Figure S11. Sensorimotor recovery trajectories stratified by age-groups and injury characteristics. The (A) motor and (B) sensory recovery remained comparable throughout the surveillance period from 2001 and 2019 and across different age groups. Figure S12. Comparison of recovery profiles between female and male patients. The recovery profiles of (A) motor function (i.e., Total motor score), (B) functional independence (i.e., SCIM), and (C) walking function were comparable between patients with traumatic and ischemic spinal cord injuries. Figure S13. Comparison of recovery profiles between patients with traumatic and ischemic injuries. The recovery profiles of (A) motor function (i.e., Total motor score), (B) functional independence (i.e., SCIM), and (C) walking function were comparable between patients with traumatic and ischemic spinal cord injuries. Table S1. Numbers and proportions of patients enrolled in the EMSCI per country (5-year bins). Table S2. Demographics and injury characteristics of included EMSCI cohort stratified by age groups. Table S3. Demographics and injury characteristics of excluded EMSCI cohort. Table S4. Mean and standard deviation of age at injury for the entire EMSCI cohort between 2001 and 2019 stratified by sex. Table S5. Model output of longitudinal analysis of demographics (i.e., sex and age) and baseline injury characteristics (i.e., injury severity and level, plegia). Table S6. Overview of longitudinal sensory and motor recovery. Patients enrolled in the EMSCI had 5 follow-up time points, while the patients participating the Sygen trial had seven. Upper extremity motor scores were computed for paraplegic patients only. We report mean (standard deviation); number of patients. Table S7. Model output of lower extremity motor score (LEMS) stratified by sex, plegia, and baseline AIS grades. Patients were enrolled in the EMSCI study. Significant values are highlighted in red. Table S8. Model output of upper extremity motor score (UEMS) stratified by sex, plegia, and baseline AIS grades. Patients were enrolled in the EMSCI study. Significant values are highlighted in red. Note: The model was only run for tetraplegic patients. Table S9. Model output of upper extremity motor score (UEMS) stratified by sex, plegia, and baseline AIS grades. Patients were enrolled in the EMSCI study. Significant values are highlighted in red. Note: The model was only run for tetraplegic patients. Table S10. Model output of total light touch score (TLT) stratified by sex, plegia, and baseline AIS grades. Patients were enrolled in the EMSCI study. Significant values are highlighted in red. Table S11. Model output of total pinprick score (TPP) stratified by sex, plegia, and baseline AIS grades. Patients were enrolled in the EMSCI study. Significant values are highlighted in red. Table S12. Model output of total sensory score (TSS) stratified by sex, plegia, and baseline AIS grades. Patients were enrolled in the EMSCI study. Significant values are highlighted in red. Table S13. Model output of SCIM Total Score stratified by sex, plegia, and baseline AIS grades. Patients were enrolled in the EMSCI study. Significant values are highlighted in red. Table S14. Model output of Walking Index for Spinal Cord Injury (WISCI), stratified by sex, plegia, and baseline AIS grades/ Patients were enrolled in the EMSCI study. Significant values are highlighted in red. Table S15. Model output of 6-minute walking test (6-MWT) stratified by sex, plegia, and baseline AIS grades. Patients were enrolled in the EMSCI study. Significant values are highlighted in red. Note: The model was only run for patients with AIS-C and D injuries. Male and female patients were pooled due to low sample numbers. Table S16. Model output of 10m walking test (10-MWT) stratified by sex, plegia, and baseline AIS grades. Patients were enrolled in the EMSCI study. Significant values are highlighted in red. Note: The model was only run for patients with AIS-C and D injuries. Table S17. Sensitivity Analysis II: Sex. Model output of total motor score, SCIM2 and 3, and WISCI stratified by plegia, and baseline AIS grades. Patients were enrolled in the EMSCI study. Significant values are highlighted in red. Table S18. Sensitivity Analysis III: Cause of Injury. Model output of total motor score, SCIM2 and 3, and WISCI stratified by plegia, and baseline AIS grades. Patients were enrolled in the EMSCI study. Significant values are highlighted in red.