A Machine Learning Approach to Concussion Risk Estimation Among Players Exhibiting Visible Signs in Professional Hockey.

BACKGROUND: The identification of concussion risk factors, such as visible signs and mechanisms of injury, improves concussion identification. Exploring individual risk factors, such as concussion history, may help to improve existing concussion risk models and algorithms. OBJECTIVES: The primary aim of the current study was to use machine learning techniques to develop a comprehensive, prospectively coded concussion risk model in professional hockey among players exhibiting visible signs. The secondary aim was to examine whether including concussion history improves model performance. METHODS: Data from the National Hockey League (NHL) spotter program, including coded visible signs and mechanisms of injury associated with possible concussive events, were extracted from the 2018-2019 to the 2021-2022 seasons. Each unique spotter event was matched with data extracted from the medical record to determine whether the event was associated with a subsequent physician diagnosed concussion. We compared the ability of three machine learning-based approaches to identify the likelihood of physician diagnosed concussion: conditional inference tree, conditional inference random forest, and logistic regression. RESULTS: A total of 1563 unique events with visible signs were identified by spotters (183 leading to a concussion diagnosis). A randomly selected training sample had 1250 events (146 concussions) and the remaining set-aside test sample had 313 events (37 concussions). The obtained models performed at a high level with large effects in the training [area under the receiver operating characteristic curve (AUC) = 0.79] and set-aside test data (AUC = 0.82). Concussion history was retained in the tree and logistic regression models, with each additional prior concussion associated with a 1.32 times increased odds of concussion diagnosis. CONCLUSIONS: We present simple tree and logistic algorithms for concussion screening and as diagnostic aids. Our results show that player concussion history can explain additional risk above and beyond that explained by visible signs and mechanisms of injury alone.

Single Leg Hop Performance After Anterior Cruciate Ligament Reconstruction: Ready for Landing but Cleared for Take-Off?

CONTEXT: Understanding former professional football players engagement with health promoting behaviors (physical exercise, high quality diet, and good sleep hygiene) will be helpful for developing lifestyle interventions to improve their feelings of well-being, a relatively understudied facet of health among this population. OBJECTIVE: Examine associations among health-promoting behaviors and subjective outcomes related to well-being among former National Football League (NFL) players. DESIGN: Cross-sectional. SETTING: Online or hard-copy survey. PATIENTS OR OTHER PARTICIPANTS: Former NFL players. MAIN OUTCOME MEASURES: Self-reported health-promoting behaviors (exercise frequency, diet quality, sleep duration and disturbance) and factors related to well-being (PROMIS ® Meaning and Purpose [MP], Self-Efficacy [SE], Ability to Participate in Social Roles and Activities [SRA]). Multivariable linear regression models were fit for each well-being-related factor with health-promoting behaviors as explanatory variables alongside select demographic, behavioral, and functional covariates. Models were fit for the full sample and separately for individual age groups: <30 years; 30-39 years; 40-49 years; 50-59 years; 60-69 years; and 70+ years. RESULTS: A total of 1,784 former NFL players (aged 52.3±16.3 years) completed the survey. Lower sleep disturbance was associated with better MP (ß[standard error]=-0.196[0.024]), SE (ß[standard error]=-0.185[0.024]), and SRA (ß[standard error]=-0.137[0.017]) in the full sample and almost all the individual age groups. More frequent moderate-to-vigorous exercise was associated with higher MP (ß[standard error]=0.068[0.025]) and SRA (ß[standard error]=0.151[0.065]) in the full sample, and with better MP, SE, and SRA among select middle-aged groups (between 40-69 years old). Diet quality, resistance training exercise frequency, other wellness activity frequency, and sleep duration were not associated with well-being-related factors in the full-group and sparse significant associations were observed in individual age group models. CONCLUSIONS: Lower sleep disturbance and more frequent moderate-to-vigorous exercise frequency may be important targets for improving overall health and well-being among former NFL players.

Longitudinal Characterization of Pain Interference and Influential Factors in Former National Football League (NFL) Players Over a 19-Year Period: An NFL-LONG Study.

Previous studies on pain experiences in retired contract sport athletes have been cross-sectional, leaving gaps in our understanding of the evolution of pain interference (PI) and factors that influence trajectories decades after sport discontinuation. This study investigated the longitudinal course of PI in former male National Football League (NFL) players over a 19-year period following sport discontinuation and examined factors influencing overall levels and trajectories of PI. Former NFL players completed health surveys in 2001, 2010, and 2019, with PI ratings measured using the 36-Item Short Form Health Survey (2001 and 2010) and the Patient-Reported Outcomes Measurement Information System (2019). Unconditional latent growth curve models analyzed overall PI severity and trajectories. Conditional latent growth curve models explored the influence of musculoskeletal injuries, osteoarthritis (OA), and depression diagnosis on PI. Over 19 years (N = 338; mean age = 48.96 ± 9.35), PI significantly increased (slope = .179, P < .001; mean Patient-Reported Outcomes Measurement Information System PI t-scores 2001 = 54.19, 2010 = 54.64, 2019 = 57.38). Cumulative musculoskeletal injuries (B = .092, P < .001) and baseline depression diagnosis (B = 4.463, P < .001) were associated with overall PI levels but not change over time. OA was significantly associated with overall PI levels (B = 6.536, P < .001) and trajectory (B = -.253, P < .001); those endorsing OA in 2001 had lower PI increases over 19 years. The body region of injury and level of play during injuries mirrored overall injury effects. PI mildly increased over 19 years, with multiple factors independently influencing overall PI levels. Enhancing former contact sport athletes' daily functionality may be achieved through holistic biopsychosocial interventions addressing musculoskeletal injuries, OA, and depression. Future research should identify factors influencing elevated trajectories of long-term PI post-sport discontinuation. PERSPECTIVE: This study assessed PI in former NFL athletes over 2 decades, revealing notable interindividual variability in trajectories over time. Musculoskeletal injuries, depression, and OA correlated with overall PI. Prevention and intervention in these 3 areas present the potential to improve disruptions in daily living due to pain in former athletes.

On-Field and Pitch-Side (Sideline) Assessment of Sports Concussion in Collision Sports: An Expert Consensus Statement Using the Modified Delphi Technique.

PURPOSE: To perform a Delphi consensus for on-field and pitch-side assessment of sports-related concussion (SRC). METHODS: Open-ended questions in rounds 1 and 2 were answered. The results of the first 2 rounds were used to develop a Likert-style questionnaire for round 3. If agreement at round 3 was ≤80% for an item, if panel members were outside consensus, or there were >30% neither agree/disagree responses, the results were carried forward into round 4. The level of agreement and consensus was defined as 90%. RESULTS: Loss of consciousness (LOC) or suspected LOC, motor incoordination/ataxia, balance disturbance, confusion/disorientation, memory disturbance/amnesia, blurred vision/light sensitivity, irritability, slurred speech, slow reaction time, lying motionless, dizziness, headaches/pressure in the head, falling to the ground with no protective action, slow to get up after a hit, dazed look, and posturing/seizures were clinical signs of SRC and indicate removal from play. Video assessment is helpful but should not replace clinical judgment. LOC/unresponsiveness, signs of cervical spine injury, suspicion of other fractures (skull/maxillo-facial), seizures, Glasgow Coma Scale score <14 and abnormal neurologic examination findings are indications for hospitalization. Return to play should only be considered when no clinical signs of SRC are present. Every suspected concussion should be referred to an experienced physician. CONCLUSIONS: Consensus was achieved for 85% of the clinical signs indicating concussion. On-field and pitch-side assessment should include the observation of the mechanism, a clinical examination, and cervical spine assessment. Of the 19 signs and red flags requiring removal from play, consensus was reached for 74%. Normal clinical examination and HIA with no signs of concussion allow return to play. Video assessment should be mandatory for professional games but should not replace clinical decision-making. Sports Concussion Assessment Tool, Glasgow Coma Scale, vestibular/ocular motor screening, Head Injury Assessment Criteria 1, and Maddocks questions are useful tools. Guidelines are helpful for non-health professionals. LEVEL OF EVIDENCE: Level V, expert opinion.

Return to Sports Following Sports-Related Concussion in Collision Sports: An Expert Consensus Statement Using the Modified Delphi Technique.

PURPOSE: To perform a Delphi consensus for return to sports (RTS) following sports-related concussion (SRC). METHODS: Open-ended questions in rounds 1 and 2 were answered. The results of the first 2 rounds were used to develop a Likert-style questionnaire for round 3. If agreement at round 3 was ≤80% for an item, if panel members were outside consensus or there were >30% neither agree/disagree responses, the results were carried forward into round 4. The level of agreement and consensus was defined as 90%. RESULTS: Individualized graduated RTS protocols should be used. A normal clinical, ocular and balance examination with no more headaches, and asymptomatic exertional test allows RTS. Earlier RTS can be considered if athletes are symptom free. The Sports Concussion Assessment Tool 5 and vestibular and ocular motor screening are recognized as useful tools to assist in decision-making. Ultimately RTS is a clinical decision. Baseline assessments should be performed at both collegiate and professional level and a combination of neurocognitive and clinical tests should be used. A specific number of recurrent concussions for season-or career-ending decisions could not be determined but will affect decision making for RTS. CONCLUSIONS: Consensus was achieved for 10 of the 25 RTS criteria: early RTS can be considered earlier than 48 to 72 hours if athletes are completely symptom-free with no headaches, a normal clinical, ocular and balance examination. A graduated RTS should be used but should be individualized. Only 2 of the 9 assessment tools were considered to be useful: Sports Concussion Assessment Tool 5 and vestibular and ocular motor screening. RTS is mainly a clinical decision. Only 31% of the baseline assessment items achieved consensus: baseline assessments should be performed at collegiate and professional levels using a combination of neurocognitive and clinical tests. The panel disagreed on the number of recurrent concussions that should be season- or career-ending. LEVEL OF EVIDENCE: Level V, expert Opinion.

The Longitudinal Relationship Between Concussion History, Years of American Football Participation, and Alcohol Use Among Former National Football League Players: an NFL-LONG Study.

OBJECTIVE: Investigate the relationships between concussion history and years of football participation (repetitive head impact proxy) with alcohol use across multiple decades in former professional football players. METHODS: Participants (n = 348; mean age = 49.0 ± 9.4) completed health questionnaires in 2001 and 2019, which included self-reported concussion history and years of participation. Alcohol use frequency and amount per occasion were reported for three timepoints: during professional career, 2001, and 2019. Ordinal logistic regression models were fit to test associations of concussion history and years of participation with alcohol use at each timepoint. RESULTS: There were no significant associations between either concussion history or years of football participation with alcohol use (frequency and amount per occasion) at any timepoint. Effect estimates for concussion history and years of football participation with alcohol use were generally comparable across timepoints. CONCLUSIONS: Later life alcohol use by former American football players is not associated with concussion history or years of exposure to football.

Pediatric Sport-Related Concussion: Recommendations From the Amsterdam Consensus Statement 2023.

The 6th International Consensus Conference on Concussion in Sport, Amsterdam 2022, addressed sport-related concussion (SRC) in adults, adolescents, and children. We highlight the updated evidence-base and recommendations regarding SRC in children (5-12 years) and adolescents (13-18 years). Prevention strategies demonstrate lower SRC rates with mouthguard use, policy disallowing bodychecking in ice hockey, and neuromuscular training in adolescent rugby. The Sport Concussion Assessment Tools (SCAT) demonstrate robustness with the parent and child symptom scales, with the best diagnostic discrimination within the first 72 hours postinjury. Subacute evaluation (>72 hours) requires a multimodal tool incorporating symptom scales, balance measures, cognitive, oculomotor and vestibular, mental health, and sleep assessment, to which end the Sport Concussion Office Assessment Tools (SCOAT6 [13+] and Child SCOAT6 [8-12]) were developed. Rather than strict rest, early return to light physical activity and reduced screen time facilitate recovery. Cervicovestibular rehabilitation is recommended for adolescents with dizziness, neck pain, and/or headaches for greater than 10 days. Active rehabilitation and collaborative care for adolescents with persisting symptoms for more than 30 days may decrease symptoms. No tests and measures other than standardized and validated symptom rating scales are valid for diagnosing persisting symptoms after concussion. Fluid and imaging biomarkers currently have limited clinical utility in diagnosing or assessing recovery from SRC. Improved paradigms for return to school were developed. The variable nature of disability and differences in evaluating para athletes and those of diverse ethnicity, sex, and gender are discussed, as are ethical considerations and future directions in pediatric SRC research.

Concussion Characteristics in the National Hockey League Before and After the Introduction of Rule 48.

Importance: A rule prohibiting a direct hit to the lateral side of the head (ie, Rule 48-Illegal Check to the Head) was introduced in the National Hockey League (NHL) in the 2010-2011 season and refined in the 2011-2012 season to widen the application to include direct contact to all areas of the head. Objective: To compare the incidence and proportion of concussions that occurred following hits to the head before and after the implementation of Rule 48. Design, Setting, and Participants: This retrospective cohort study used a before and after design to evaluate concussions among NHL players in regular season games. Data from the 4 seasons preceding the implementation of Rule 48 (2006-2007 to 2009-2010) were compared with data from 5 seasons following its implementation (2014-2015 to 2018-2019). Data were analyzed from October 31, 2021, to November 30, 2022. Main Outcomes and Measures: The incidence and relative proportion of concussion characteristics and mechanisms before and after the introduction of Rule 48. Results: In the analysis of 688 concussions for NHL seasons spanning 2006 to 2010 (n = 231) and 2014 to 2019 (n = 457), there was an overall increase in the incidence of concussion between the 2 time frames, although the incidence of concussions due to hits to the lateral aspect of the head decreased from 1.6/100 games to 1.0/100 games (estimated difference, 0.6/100 games [90% credible interval (CrI), 0.30/100 games to 0.90/100 games). There was also a reduction of 18.8 (90% CrI, 13.0-23.7) percentage points in the proportion of concussions due to hits to the lateral aspect of the head from 80 of 231 concussions (34.6%) to 61 of 457 concussions (13.3%). The incidence of concussions following hits to the head from body checks using the shoulder, arm, and glove was similar before and following the implementation of Rule 48. However, the proportion was reduced 14.7 percentage points from 113 of 231 concussions (48.9%) before to 149 of 457 concussions (32.6%) after implementation of Rule 48 (90% CrI of the difference, 8.9-20.7 percentage points). Conclusions and Relevance: The findings of this cohort study of NHL players suggest that after the introduction of Rule 48, the incidence rate and proportion of concussions from contact to the lateral aspect of the head decreased, as did the proportion of concussions following direct hits to the head.

Subjective and Performance-Based Cognition and Their Associations with Head Injury History in Older Former National Football League Players.

PURPOSE: Investigate the association between self-reported subjective and performance-based cognition among older (50-70 years) former professional American football players, as well as the relationship of cognitive measures with concussion history and years of football participation, as a proxy for repetitive head impact exposure. METHODS: Among older former National Football League (NFL) players ( N = 172; mean age = 60.69 ± 5.64), associations of subjective (Patient Reported Outcome Measurement Information System Cognitive Function-Short Form) and performance-based cognitive measures (Brief Test of Adult Cognition by Telephone [BTACT] Executive Function and Episodic Memory indices) were assessed via univariable and multivariable regression models, with a priori covariates of depression and race. A similar univariate and multivariable regression approach assessed associations between concussion history and years of football participation with subjective and performance-based cognitive measures. In a sample subset ( n = 114), stability of subjective cognitive rating was assessed via partial correlation. RESULTS: Subjective ratings of cognition were significantly associated with performance-based assessment, with moderate effect sizes (episodic memory ηp2 = 0.12; executive function ηp2 = 0.178). These associations were weakened, but remained significant ( P s < 0.05), with the inclusion of covariates. Greater concussion history was associated with lower subjective cognitive function ( ηp2 = 0.114, P < 0.001), but not performance-based cognition. The strength of association between concussion history and subjective cognition was substantially weakened with inclusion of covariates ( ηp2 = 0.057). Years of participation were not associated with measures of subjective or objective cognition ( P s > 0.05). CONCLUSIONS: These findings reinforce the importance of comprehensive evaluation reflecting both subjective and objective measures of cognition, as well as the consideration of patient-specific factors, as part of a comprehensive neurobehavioral and health assessment of older former contact sport athletes.

When should an athlete retire or discontinue participating in contact or collision sports following sport-related concussion? A systematic review.

OBJECTIVE: To systematically review the scientific literature regarding factors to consider when providing advice or guidance to athletes about retirement from contact or collision sport following sport-related concussion (SRC), and to define contraindications to children/adolescent athletes entering or continuing with contact or collision sports after SRC. DATA SOURCES: Medline, Embase, SPORTSDiscus, APA PsycINFO, CINAHL and Cochrane Central Register of Controlled Trials were searched systematically. STUDY ELIGIBILITY CRITERIA: Studies were included if they were (1) original research, (2) reported on SRC as the primary source of injury, (3) evaluated the history, clinical assessment and/or investigation of findings that may preclude participation in sport and (4) evaluated mood disturbance and/or neurocognitive deficits, evidence of structural brain injury or risk factors for increased risk of subsequent SRC or prolonged recovery. RESULTS: Of 4355 articles identified, 93 met the inclusion criteria. None of the included articles directly examined retirement and/or discontinuation from contact or collision sport. Included studies examined factors associated with increased risk of recurrent SRC or prolonged recovery following SRC. In general, these were low-quality cohort studies with heterogeneous results and moderate risk of bias. Higher number and/or severity of symptoms at presentation, sleep disturbance and symptom reproduction with Vestibular Ocular Motor Screen testing were associated with prolonged recovery and history of previous concussion was associated with a risk of further SRC. CONCLUSION: No evidence was identified to support the inclusion of any patient-specific, injury-specific or other factors (eg, imaging findings) as absolute indications for retirement or discontinued participation in contact or collision sport following SRC. PROSPERO REGISTRATION NUMBER: CRD42022155121.

Role of biomarkers and emerging technologies in defining and assessing neurobiological recovery after sport-related concussion: a systematic review.

OBJECTIVE: Determine the role of fluid-based biomarkers, advanced neuroimaging, genetic testing and emerging technologies in defining and assessing neurobiological recovery after sport-related concussion (SRC). DESIGN: Systematic review. DATA SOURCES: Searches of seven databases from 1 January 2001 through 24 March 2022 using keywords and index terms relevant to concussion, sports and neurobiological recovery. Separate reviews were conducted for studies involving neuroimaging, fluid biomarkers, genetic testing and emerging technologies. A standardised method and data extraction tool was used to document the study design, population, methodology and results. Reviewers also rated the risk of bias and quality of each study. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Studies were included if they: (1) were published in English; (2) represented original research; (3) involved human research; (4) pertained only to SRC; (5) included data involving neuroimaging (including electrophysiological testing), fluid biomarkers or genetic testing or other advanced technologies used to assess neurobiological recovery after SRC; (6) had a minimum of one data collection point within 6 months post-SRC; and (7) contained a minimum sample size of 10 participants. RESULTS: A total of 205 studies met inclusion criteria, including 81 neuroimaging, 50 fluid biomarkers, 5 genetic testing, 73 advanced technologies studies (4 studies overlapped two separate domains). Numerous studies have demonstrated the ability of neuroimaging and fluid-based biomarkers to detect the acute effects of concussion and to track neurobiological recovery after injury. Recent studies have also reported on the diagnostic and prognostic performance of emerging technologies in the assessment of SRC. In sum, the available evidence reinforces the theory that physiological recovery may persist beyond clinical recovery after SRC. The potential role of genetic testing remains unclear based on limited research. CONCLUSIONS: Advanced neuroimaging, fluid-based biomarkers, genetic testing and emerging technologies are valuable research tools for the study of SRC, but there is not sufficient evidence to recommend their use in clinical practice. PROSPERO REGISTRATION NUMBER: CRD42020164558.

What tests and measures accurately diagnose persisting post-concussive symptoms in children, adolescents and adults following sport-related concussion? A systematic review.

OBJECTIVE: To determine what tests and measures accurately diagnose persisting post-concussive symptoms (PPCS) in children, adolescents and adults following sport-related concussion (SRC). DESIGN: A systematic literature review. DATA SOURCES: MEDLINE, Embase, PsycINFO, Cochrane Central Register of Controlled Trials, CINAHL and SPORTDiscus through March 2022. ELIGIBILITY CRITERIA: Original, empirical, peer-reviewed findings (cohort studies, case-control studies, cross-sectional studies and case series) published in English and focused on SRC. Studies needed to compare individuals with PPCS to a comparison group or their own baseline prior to concussion, on tests or measures potentially affected by concussion or associated with PPCS. RESULTS: Of 3298 records screened, 26 articles were included in the qualitative synthesis, including 1016 participants with concussion and 531 in comparison groups; 7 studies involved adults, 8 involved children and adolescents and 11 spanned both age groups. No studies focused on diagnostic accuracy. Studies were heterogeneous in participant characteristics, definitions of concussion and PPCS, timing of assessment and the tests and measures examined. Some studies found differences between individuals with PPCS and comparison groups or their own pre-injury assessments, but definitive conclusions were not possible because most studies had small convenience samples, cross-sectional designs and were rated high risk of bias. CONCLUSION: The diagnosis of PPCS continues to rely on symptom report, preferably using standardised symptom rating scales. The existing research does not indicate that any other specific tool or measure has satisfactory accuracy for clinical diagnosis. Future research drawing on prospective, longitudinal cohort studies could help inform clinical practice.

Examining later-in-life health risks associated with sport-related concussion and repetitive head impacts: a systematic review of case-control and cohort studies.

OBJECTIVE: Concern exists about possible problems with later-in-life brain health, such as cognitive impairment, mental health problems and neurological diseases, in former athletes. We examined the future risk for adverse health effects associated with sport-related concussion, or exposure to repetitive head impacts, in former athletes. DESIGN: Systematic review. DATA SOURCES: Search of MEDLINE, Embase, Cochrane, CINAHL Plus and SPORTDiscus in October 2019 and updated in March 2022. ELIGIBILITY CRITERIA: Studies measuring future risk (cohort studies) or approximating that risk (case-control studies). RESULTS: Ten studies of former amateur athletes and 18 studies of former professional athletes were included. No postmortem neuropathology studies or neuroimaging studies met criteria for inclusion. Depression was examined in five studies in former amateur athletes, none identifying an increased risk. Nine studies examined suicidality or suicide as a manner of death, and none found an association with increased risk. Some studies comparing professional athletes with the general population reported associations between sports participation and dementia or amyotrophic lateral sclerosis (ALS) as a cause of death. Most did not control for potential confounding factors (eg, genetic, demographic, health-related or environmental), were ecological in design and had high risk of bias. CONCLUSION: Evidence does not support an increased risk of mental health or neurological diseases in former amateur athletes with exposure to repetitive head impacts. Some studies in former professional athletes suggest an increased risk of neurological disorders such as ALS and dementia; these findings need to be confirmed in higher quality studies with better control of confounding factors. PROSPERO REGISTRATION NUMBER: CRD42022159486.

Beyond acute concussion assessment to office management: a systematic review informing the development of a Sport Concussion Office Assessment Tool (SCOAT6) for adults and children.

OBJECTIVES: To systematically review the scientific literature regarding the assessment of sport-related concussion (SRC) in the subacute phase (3-30 days) and provide recommendations for developing a Sport Concussion Office Assessment Tool (SCOAT6). DATA SOURCES: MEDLINE, Embase, PsycINFO, Cochrane CENTRAL, CINAHL, SPORTDiscus and Web of Science searched from 2001 to 2022. Data extracted included study design, population, definition of SRC diagnosis, outcome measure(s) and results. ELIGIBILITY CRITERIA: (1) Original research, cohort studies, case-control studies, diagnostic accuracy and case series with samples >10; (2) SRC; (3) screening/technology that assessed SRC in the subacute period and (4) low risk of bias (ROB). ROB was performed using adapted Scottish Intercollegiate Guidelines Network criteria. Quality of evidence was evaluated using the Strength of Recommendation Taxonomy classification. RESULTS: Of 9913 studies screened, 127 met inclusion, assessing 12 overlapping domains. Results were summarised narratively. Studies of acceptable (81) or high (2) quality were used to inform the SCOAT6, finding sufficient evidence for including the assessment of autonomic function, dual gait, vestibular ocular motor screening (VOMS) and mental health screening. CONCLUSION: Current SRC tools have limited utility beyond 72 hours. Incorporation of a multimodal clinical assessment in the subacute phase of SRC may include symptom evaluation, orthostatic hypotension screen, verbal neurocognitive tests, cervical spine evaluation, neurological screen, Modified Balance Error Scoring System, single/dual task tandem gait, modified VOMS and provocative exercise tests. Screens for sleep disturbance, anxiety and depression are recommended. Studies to evaluate the psychometric properties, clinical feasibility in different environments and time frames are needed. PROSPERO REGISTRATION NUMBER: CRD42020154787.