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Chronic subdural hematoma (CSDH) is increasingly common, particularly in the older and multimorbid population. Surgical proficiency in management is required in the early years of U.K. neurosurgical training with most cases performed by nonconsultant-grade surgeons. The aim of this systematic review was to examine the effect of surgeon seniority on recurrence for patients with CSDH. Full-text articles comparing surgical treatment for CSDH with a "senior" (consultant/attending level) or "junior" (resident/registrar or similar) lead surgeon were identified. MEDLine and EMBASE databases were searched. The primary outcome of this study was recurrence. Secondary outcomes included postoperative complications and mortality rate. A random effects meta-analysis was performed. The risk of bias was assessed using the National Institute of Health risk of bias toolkit. Five studies were included in the final analysis (n = 941 total patients). Individually, no study identified a significant difference in recurrence rate and postoperative complications between senior and junior neurosurgeons. On meta-analysis, junior-led evacuations had lower recurrence rates on pooled univariable analysis (12.0% vs. 17.9% [odds ratio 0.48, 95% confidence interval 0.29-0.78, I2 = 0%]) (3 studies). Seniority of surgeon was not associated with increased rates of recurrence patients undergoing CSDH surgery. Complexity of operation may be a confounding factor in observed lower recurrence rates with more junior operators., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: Split cord malformation (SCM) is a rare congenital malformation of the spinal cord in which the cord is split longitudinally. Identification and diagnosis in adulthood is rare, with the majority of cases diagnosed in the paediatric population. Isolated segmental cervical SCM is rarer still., Case Presentation: Here, the authors present the case of a 26-year-old female who presented with neck pain and longstanding bimanual synkinesis secondary to an isolated type II SCM in the C4-C7 region. The authors present this novel presenting symptom in adulthood and finding of isolated cervical SCM with associated blocked cervical vertebrae, in an otherwise normal neuroaxis and spinal column., Conclusions: The case serves to highlight the importance of knowledge of this rare congenital condition to surgeons, physicians and radiologists involved in the care of both adult and paediatric patients presenting with spinal pathology., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Degenerative cervical myelopathy (DCM) is the commonest cause of adult spinal cord dysfunction worldwide, for which surgery is the mainstay of treatment. At present, there is limited literature on the costs associated with the surgical management of DCM, and none from the United Kingdom (UK). This study aimed to evaluate the cost-effectiveness of DCM surgery within the National Health Service, UK., Materials and Methods: Incidence of DCM was identified from the Hospital Episode Statistics (HES) database for a single year using five ICD-10 diagnostic codes to represent DCM. Health Resource Group (HRG) data was used to estimate the mean incremental surgery (treatment) costs compared to non-surgical care, and the incremental effect (quality adjusted life year (QALY) gain) was based on data from a previous study. A cost per QALY value of <£30,000/QALY (GBP) was considered acceptable and cost-effective, as per the National Institute for Health and Clinical Excellence (NICE) guidance. A sensitivity analysis was undertaken (±5%, ±10% and ±20%) to account for variance in both the cost of admission and QALY gain., Results: The total number of admissions for DCM in 2018 was 4,218. Mean age was 62 years, with 54% of admissions being of working age (18-65 years). The overall estimated cost of admissions for DCM was £38,871,534 for the year. The mean incremental (per patient) cost of surgical management of DCM was estimated to be £9,216 (ranged £2,358 to £9,304), with a QALY gain of 0.64, giving an estimated cost per QALY value of £14,399/QALY. Varying the QALY gain by ±20%, resulted in cost/QALY figures between £12,000 (+20%) and £17,999 (-20%)., Conclusions: Surgery is estimated to be a cost-effective treatment of DCM amongst the UK population.

A chronic subdural haematoma (CSDH) is a collection of aged blood between the dura and the brain, typically treated with surgical evacuation. Many patients with CSDH have comorbidities requiring the use of antithrombotic medications. The optimal management of these medications in the context of CSDH remains unknown, as the risk of recurrence must be carefully weighed against the risk of vaso-occlusive events. To better understand these risks and inform the development of clinical practice guidelines, we conducted a systematic review and meta-analysis. A systematic review was conducted in accordance with the PRISMA guidelines, searching Medline and Embase databases. The study was registered with PROSPERO (CRD42023397061). A total of 44 studies were included, encompassing 1 prospective cohort study and 43 retrospective cohort studies. Pooled odds ratios (ORs) were calculated for CSDH recurrence and vaso-occlusive events in patients taking anticoagulant or antiplatelet medications compared to patients not receiving antithrombotic therapy. GRADE was used to assess the quality of evidence. In patients on anticoagulant therapy at CSDH diagnosis, the pooled OR for CSDH recurrence was 1.41 (95% CI 1.11 to 1.79; I 2 = 28%). For patients on antiplatelet therapy, the pooled OR was 1.31 (95% CI 1.08 to 1.58; I 2 = 32%). Patients taking antithrombotic medications had a significantly higher risk of vaso-occlusive events, with a pooled OR of 3.74 (95% CI 2.12 to 6.60; I 2 = 0%). There was insufficient evidence to assess the impact of time to recommence antithrombotic medication on CSDH outcomes. We found that baseline antithrombotic use is associated with the risk of CSDH recurrence and vaso-occlusive events following surgical evacuation. The evidence base is of low quality, and decisions regarding antithrombotic therapy should be individualised for each patient. Further high-quality, prospective studies or registry-based designs are needed to better inform clinical decision-making and establish evidence-based guidelines.

Purpose: Both phenotypic and genotypic variations now underpin glioma classification, thus helping to more accurately guide their clinical management. However, WHO Grade III anaplastic astrocytoma (AA) remains an unpredictable, heterogeneous entity; displaying a variable prognosis, clinical course and treatment response. This study aims to examine whether additional tumour characteristics influence either overall survival (OS) or 3-year survival in AA., Materials and Methods: Data were collected on all newly diagnosed cases of AA between 2003 and 2014, followed up for a minimum of 3 years. Molecular information was obtained from case records and if missing, was re-analysed. Histological slides were independently examined for Ki-67 proliferation index, cellularity and number of mitotic figures. Kaplan-Meier and Cox regression analyses were used to assess OS., Results: In total, 50 cases were included with a median OS of 14.5 months (range: 1-150 months). Cumulative 3-year survival was 31.5%. Median age was 50 years (range: 24 - 77). Age, IDH1 mutation status, lobar location, oncological therapy and surgical resection were significant independent prognostic indicators for OS. In cases demonstrating an OS   ≥   3 years ( n   15), Ki-67 index, number of mitotic figures and percentage areas of 'high cellularity' were significantly reduced, i.e. more characteristic of lower-grade/WHO Grade II glioma.  15), Ki-67 index, number of mitotic figures and percentage areas of 'high cellularity' were significantly reduced, i.e. more characteristic of lower-grade/WHO Grade II glioma., Conclusions: IDH1 status, age, treatment and location remain the most significant prognostic indicators for patients with AA. However, Ki-67 index, mitotic figures and cellularity may help identify AA cases more likely to survive < 3 years, i.e. AA cases more similar to glioblastoma and those cases more likely to survive > 3 years, i.e. more similar to a low-grade glioma.

Background: Although resection of mesial temporal lobe lesions can be achieved with relatively low morbidity, resective surgery is not without risk. Whilst many lesions found in the anterior mesiotemporal lobe are low-grade entities, transforming and high-grade lesions have also been demonstrated. We investigate the feasibility of utilising serial quantitative volumetric imaging, to determine if a strategy of imaging surveillance can be safely employed for the management of radiologically diagnosed anterior mesial temporal low-grade tumours without a confirmed histological diagnosis., Methods: A retrospective case-note and radiology review design were utilised. The primary presenting symptomatology was recorded together with the efficacy of symptomatic control. Volumetric analysis of MRI images was performed using Brainlab software. Pre- and post-operative neuropsychological data were analysed., Results: 35 patients were identified with a radiological diagnosis of a low-grade anterior mesial temporal lobe tumour. Of these, 29% ( n  = 10) underwent surgical resection. For the whole cohort, the mean tumour volume at diagnosis was 6.5cm 3 , with a mean volumetric expansion of 1.4% per month. A significant difference was found between the volumetric expansion rate of those that underwent surgical treatment and those that did not (4.9% per month vs 0.06% per month, p  < .01). Of those cases that did not undergo surgical resection, no significant difference was seen between the initial diagnostic volume and the volume at the time of their most recent interval surveillance scan ( p  = .97). New onset epilepsy was significantly associated with a requirement for eventual surgical tumour resection; relative risk = 6.25, 95% CI = 1.5-25.9, p  = .0114., Conclusion: Where medical seizure control is adequate, we suggest that conservative management is feasible even in the absence of a confirmed histological diagnosis. However, in patients aged over 50 years with new onset epilepsy, a lower threshold for intervention should be considered.

Objective: We aim to compare the effectiveness of dural closure techniques in preventing cerebrospinal fluid (CSF) leaks following surgery for intradural lesions and seek to identify additional factors associated with CSF leaks. Surgical management of spinal intradural lesions involves durotomy which requires a robust repair to prevent postoperative CSF leakage. The ideal method of dural closure and the efficacy of sealants has not been established in literature., Methods: We performed a retrospective analysis of all intradural spinal cases performed at a tertiary spine centre from 1 April 2015 to 29 January 2020 and collected data on patient bio-profile, dural repair technique, and CSF leak rates. Multivariate analysis was performed to identify predictors for postoperative CSF leak., Results: A total of 169 cases were reported during the study period. There were 15 cases in which postoperative CSF leak was reported (8.87%). Multivariate analysis demonstrated that patient age (odds ratio [OR], 0.942; 95% confidence interval [CI], 0.891-0.996), surgical indication listed in the "others" category (OR, 44.608; 95% CI, 1.706-166.290) and dural closure with suture, sealant and patch (OR, 22.235; 95% CI, 2.578-191.798) were factors associated with CSF leak. Postoperative CSF leak was associated with the risk of surgical site infection with a likelihood ratio of 8.704 (χ² (1) = 14.633, p < 0.001)., Conclusion: Identifying predictors for CSF leaks can assist in the counselling of patients with regard to surgical risk and expected postoperative recovery.

Purpose: Degenerative cervical myelopathy (DCM) is the most common cause of adult spinal cord dysfunction worldwide. However, the current incidence of DCM is poorly understood. The Hospital Episode Statistics (HES) database contains details of all secondary care admissions across NHS hospitals in England. This study aimed to use HES data to characterise surgical activity for DCM in England., Methods: The HES database was interrogated for all cases of DCM between 2012 and 2019. DCM cases were identified from 5 ICD-10 codes. Age-stratified values were collected for 'Finished Consultant Episodes' (FCEs), which correspond to a patient's hospital admission under a lead clinician. Data was analysed to explore current annual activity and longitudinal change., Results: 34,903 FCEs with one or more of the five ICD-10 codes were identified, of which 18,733 (53.6%) were of working age (18-64 years). Mean incidence of DCM was 7.44 per 100,000 (SD ± 0.32). Overall incidence of DCM rose from 6.94 per 100,000 in 2012-2013 to 7.54 per 100,000 in 2018-2019. The highest incidence was seen in 2016-2017 (7.94 per 100,000). The median male number of FCEs per year (2919, IQR: 228) was consistently higher than the median female number of FCEs per year (2216, IQR: 326). The rates of both emergency admissions and planned admissions are rising., Conclusions: The incidence of hospitalisation for DCM in England is rising. Health care policymakers and providers must recognise the increasing burden of DCM and act to address both early diagnoses and access to treatment in future service provision plans., (© 2022. The Author(s).)

Purpose: To investigate the incidence of complications from lumbar decompression ± discectomy surgery for cauda equina syndrome (CES), assessing whether time of day is associated with a change in the incidence of complications., Methods: Electronic clinical and operative notes for all lumbar decompression operations undertaken at our institution for CES over a 2-year time period were retrospectively reviewed. "Overnight" surgery was defined as any surgery occurring between 18:00 and 08:00 on any day. Clinicopathological characteristics, surgical technique, and peri/post-operative complications were recorded. Multivariable logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals., Results: A total of 81 lumbar decompression operations were performed in the 2-year period and analysed. A total of 29 (36%) operations occurred overnight. Complete CES (CESR) was seen in 13 cases (16%) in total, 7 of whom underwent surgery during the day. Exactly 27 complications occurred in 24 (30%) patients. The most frequently occurring complication was a dural tear (n = 21, 26%), followed by post-operative haematoma, infection, and residual disc. Complication rates in the CESR cohort (54%) were significantly greater than in the CES incomplete (CESI) cohort (25%) (p = 0.04). On multivariable analysis, overnight surgery was independently associated with a significantly increased complication rate (OR 2.83, CI 1.02-7.89)., Conclusions: Lumbar decompressions performed overnight for CES were more than twice as likely to suffer a complication, in comparison to those performed within daytime hours. Our study suggests that out-of-hours operating, particularly at night, must be clinically justified and should not be influenced by day-time operating capacity., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

The corona virus disease 2019 (COVID-19) pandemic has had a wide-ranging impact on the clinical practice of medicine and emotional well-being of providers. Our aim was to determine the impact of the COVID-19 pandemic on practice and burnout among hepatology providers. From February to March 2021, we conducted an electronic survey of American Association for the Study of Liver Diseases (AASLD) members who were hepatologists, gastroenterologists, and advanced practice providers (APPs). The survey included 26 questions on clinical practice and emotional well-being derived from validated instruments. A total of 230 eligible members completed the survey as follows: 107 (47%) were adult transplant hepatologists, 43 (19%) were adult general hepatologists, 14 (6%) were adult gastroenterologists, 11 (5%) were pediatric hepatologists, 45 (19%) were APPs, and 9 (4%) were other providers. We found that 69 (30%) experienced a reduction in compensation, 92 (40%) experienced a reduction in staff, and 9 (4%) closed their practice; 100 (43%) respondents reported experiencing burnout. In univariate analysis, burnout was more frequently reported in those ≤55 years old (odds ratio [OR], 2.2; 95% confidence interval [CI], 1.2-4.2), women (OR, 2.2; 95% CI, 1.3-3.7), nontransplant hepatology (OR, 2.0; 95% CI, 1.1-3.3), APPs (OR, 2.7; 95% CI, 1.4-5.1), and those less than 10 years in practice (OR, 1.9; 95% CI, 1.1-3.3). In multivariable analysis, only age ≤55 years was associated with burnout (OR, 2.3; 95% CI, 1.1-4.8). The most common ways the respondents suggested the AASLD could help was through virtual platforms for networking, mentoring, and coping with the changes in practice due to the COVID-19 pandemic. Conclusion: The COVID-19 pandemic has had a substantial impact on the clinical practice of hepatology as well as burnout and emotional well-being. Women, APPs, and early and mid-career clinicians more frequently reported burnout. Identified strategies to cope with burnout include virtual platforms to facilitate networking and mentoring., (© 2021 The Authors. Hepatology Communications published by Wiley Periodicals LLC on behalf of American Association for the Study of Liver Diseases.)

Introduction: Lumbar decompression (LD) surgery, with or without discectomy, is a commonly performed surgical procedure. Despite the concept of day-case LD being reported as early as the 1980s, day-case LD is yet to become routine clinical practice., Research Question: This systematic review aimed to examine the published literature on the safety and complication rates of day-case LD. Secondary outcome measures, including the economic impact and patient satisfaction of day-case LD, were also examined., Materials and Methods: A systematic electronic search was carried out on PubMed, EMBASE and the Cochrane Library between 1999 and January 2022. Studies were screened against predefined inclusion/exclusion criteria with the quality of included studies subsequently being assessed., Results: In total, 15 studies were included in this review. The majority of studies were undertaken in the USA (n ​= ​8, 53%) and were of a case series design (n ​= ​9, 60%). Reported complication rates ranged from 0% to 7.8%, with nine studies reporting a complication rate of <4%. Readmission rates ranged from 0% to 7.7%. Seven studies quoted a readmission rate of 0%. Five studies found cost saving benefits of day-case LD in comparison to inpatient LD of up to $27,984 (USD). Patient acceptability of day-case LD was consistently high across the six studies that assessed it., Discussion and Conclusion: Day-case LD surgery is a safe and economically efficient surgical option in appropriately selected patients., Competing Interests: None of the authors declare any conflicts of interest. No financial funding was received for this study., (© 2022 The Authors.)

Background: Patients with chronic hepatitis C and risky/harmful alcohol use experience poor outcomes. Granular data evaluating whether alcohol counseling during hepatitis C treatment impacts longitudinal alcohol consumption are lacking., Aims: To evaluate whether provider-delivered counseling in the context of direct-acting antiviral hepatitis C treatment associates with decreased longitudinal alcohol consumption., Methods: We performed secondary data analysis from the Hep ART study including adults with hepatitis C who underwent provider-delivered counseling during direct-acting antiviral treatment between October 2014 and September 2017. Demographics and disease characteristics were summarized. Alcohol consumption, abstinence, and heavy drinking were evaluated in periods before, during, and after direct-acting antiviral treatment. Multivariate regression analyses were performed to evaluate the association of alcohol consumption with each 12-week time period for all patients and a subsample with cirrhosis., Results: One hundred twenty-three patients were included; 41 had cirrhosis. Most patients were male (74.0%) and Black (58.5%). Alcohol consumption improved during direct-acting antiviral treatment and was notably sustained (< 12 weeks before treatment 32.5 g/day; during treatment 20.0 g/day; and 12-24 weeks after treatment 23.7 g/day). Multivariable analyses showed significantly improved alcohol consumption metrics during and after antiviral treatment compared to < 12 weeks before treatment (during treatment 13.04 g/day less, p = 0.0001; > 24 weeks after treatment 15.29 g/day less, p = 0.0001). The subsample with cirrhosis showed similar results (during treatment 13.21 g/day less, p = 0.0001; > 24 weeks after treatment 7.69 g/day less, p = 0.0001)., Conclusions: Patients with chronic HCV and risky/harmful alcohol use given provider-delivered alcohol-related counseling during HCV treatment sustain decreased alcohol consumption patterns during and after treatment., (© 2020. Springer Science+Business Media, LLC, part of Springer Nature.)

Objectives: To assess the reporting of study design and characteristics in multi-level degenerative cervical myelopathy (DCM) treated by posterior surgical approaches, and perform a comparison of clinical and radiographic outcomes between different approaches., Methods: A literature search was performed in Embase and MEDLINE between 1995-2019 using a sensitive search string combination. Studies were selected by predefined selection criteria: Full text articles in English, with >10 patients (prospective) or >50 patients (retrospective), reporting outcomes of multi-level DCM treated by posterior surgical approach., Results: A total of 75 studies involving 19,510 patients, conducted worldwide, were identified. Laminoplasty was described in 56 studies (75%), followed by laminectomy with (36%) and without fusion (16%). The majority of studies were conducted in Asia (84%), in the period of 2016-2019 (51%), of which laminoplasty was studied predominantly. Twelve (16%) prospective studies and 63 (84%) retrospective studies were identified. The vast majority of studies were conducted in a single centre (95%) with clear inclusion/exclusion criteria and explicit cause of DCM. Eleven studies (15%) included patients with ossification of the posterior longitudinal ligament exclusively with cohorts of 57 to 252. The clinical and radiographic outcomes were reported with heterogeneity when comparing laminoplasty, laminectomy with and without fusion., Conclusions: Heterogeneity in the reporting of study and sample characteristics exists, as well as in clinical and radiographic outcomes, with a paucity of studies with a higher level of evidence. Future studies are needed to elucidate the clinical effectiveness of posterior surgical treatments.

Purpose: Evidence exists, in CNS germinomas and medulloblastomas (MB), that patient sex significantly influences incidence and outcome. The role of sex genotype in other paediatric CNS tumours remains unclear. This study sought to examine the role of sex genotype in CNS tumour incidence and overall survival (OS)., Methods: Age-adjusted incidence and OS rates were collected from the Surveillance Epidemiology and End Result (SEER) registry between 2000 and 2011 for common paediatric (<=19 years) CNS tumours: pilocytic astrocytoma (PA), anaplastic astrocytoma, glioblastoma (GBM), medulloblastoma, supratentorial CNS embryonal tumour, ependymoma, and germinoma. All patients with histologically confirmed, ICD-03 coded, first tumours, were included. Kaplan-Meier and Cox regression analyses were used to calculate hazard ratios (HR)., Results: The total cases are as follows: males=3018 and females=2276. Highest incidence was seen in PA (n=2103). GBM displayed the worst OS, whilst PA displayed the best. Higher incidence was observed in males for all tumours, except PA. Females with ependymoma had significantly better OS compared to males, whereas males with germinomas had better OS compared to females. Females <1 year with AA had better OS than males. Increasing age significantly improved male and female survival in ependymoma and medulloblastoma., Conclusion: Interrogating population-based registries such as SEER minimises bias and provides credible data. Observed differences in incidence and OS between the sexes for different paediatric CNS tumours provide useful prognostic information for clinicians. Sex genotype was a significant independent prognostic factor in ependymomas and germinomas. Further investigation of possible epigenetic and hormonal differences may provide sex-specific vulnerabilities that may be exploitable for targeted therapy.

Degenerative cervical myelopathy (DCM) results from compression of the cervical spine cord as a result of age related changes in the cervical spine, and affects up to 2% of adults, leading to progressive disability. Surgical decompression is the mainstay of treatment, but there remains significant variation in surgical approaches used. This survey was conducted in order to define current practice amongst spine surgeons worldwide, as a possible prelude to further studies comparing surgical approaches., Methods: An electronic survey was developed and piloted by the investigators using SurveyMonkey. Collected data was categorical and is presented using summary statistics. Where applicable, statistical comparisons were made using a Chi-Squared test. The level of significance for all statistical analyses was defined as p < 0.05. All analysis, including graphs was performed using R (R Studio)., Results: 127 surgeons, from 30 countries completed the survey; principally UK (66, 52%) and North America (15, 12%). Respondents were predominantly Neurosurgeons by training (108, 85%) of whom 84 (75%) reported Spinal Surgery as the principal part of their practice. The majority indicated they selected their surgical procedure for multi-level DCM on a case by case basis (62, 49%). Overall, a posterior approach was more popular for multi-level DCM (74, 58%). Region, speciality or annual multi-level case load did not influence this significantly. However, there was a trend for North American surgeons to be more likely to favour a posterior approach., Conclusions: A posterior approach was favoured and more commonly used to treat multi-level DCM, in an international cohort of surgeons. Posterior techniques including laminectomy, laminectomy and fusion or laminoplasty appeared to be equally popular., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Background: Intramedullary spinal cord tumours are relatively rare tumours of the central nervous system. Surgical outcomes are affected by many variables, including pre-operative neurological function, tumour histology and extent of resection. Emphasis remains on surgical treatment due to limited adjunctive therapeutic options and poor drug penetration., Objective: To identify clinically relevant predictors of progression free survival by retrospectively analysing the extent of resection, pre- and post-operative neurological function and histology in intramedullary spinal cord tumours from a single neurosurgical centre over 10 years., Methods: Forty-three adult cases were identified from a surgical database. Variables collected included pre-and post-operative Frankel Grade and Modified McCormick Scale assessments, tumour histology, extent of resection and length of follow up. Chi-Squared, Kaplan-Mier Survival and Mann-Whitney U -tests were completed., Results: Ependymoma (41.9%) and haemangioblastoma (14.0%) were the commonest tumour histologies. In total, 17 different histological tumours were identified in the series. There was a statistically significant relationship between identification of the tumour plane and extent of resection ( p  < 0.01), along with the extent of resection and recurrence ( p  = 0.04). Compared to the other histological subtypes, ependymoma's demonstrated a significantly greater extent of resection ( p  = 0.01). There was a significant relationship between the grade of tumour and progression-free survival ( p  < 0.01)., Conclusion: Tumour plane and the extent of tumour resection are significant determinants of progression-free survival. Ependymoma, whilst being the commonest histology in our series were also the most resectable. Whilst complete resection reduces the rate of recurrence, tumour grade is the most important predictor of outcome. Given the importance of the extent of resection, and following a similar trend to other low volume pathologies, these tumours should only be tackled by neurosurgeons with experience in their resection.

Context: - Relatively little is known about the significance and potential impact of glass-digital discordances, and this is likely to be of importance when considering digital pathology adoption., Objective: - To apply evidence-based medicine to collect and analyze reported instances of glass-digital discordance from the whole slide imaging validation literature., Design: - We used our prior systematic review protocol to identify studies assessing the concordance of light microscopy and whole slide imaging between 1999 and 2015. Data were extracted and analyzed by a team of histopathologists to classify the type, significance, and potential root cause of discordances., Results: - Twenty-three studies were included, yielding 8069 instances of a glass diagnosis being compared with a digital diagnosis. From these 8069 comparisons, 335 instances of discordance (4%) were reported, in which glass was the preferred diagnostic medium in 286 (85%), and digital in 44 (13%), with no consensus in 5 (2%). Twenty-eight discordances had the potential to cause moderate/severe patient harm. Of these, glass was the preferred diagnostic medium for 26 (93%). Of the 335 discordances, 109 (32%) involved the diagnosis or grading of dysplasia. For these cases, glass was the preferred diagnostic medium in 101 cases (93%), suggesting that diagnosis and grading of dysplasia may be a potential pitfall of digital diagnosis. In 32 of 335 cases (10%), discordance on digital was attributed to the inability to find a small diagnostic/prognostic object., Conclusions: - Systematic analysis of concordance studies reveals specific areas that may be problematic on whole slide imaging. It is important that pathologists are aware of these areas to ensure patient safety.

Context: -Light microscopy (LM) is considered the reference standard for diagnosis in pathology. Whole slide imaging (WSI) generates digital images of cellular and tissue samples and offers multiple advantages compared with LM. Currently, WSI is not widely used for primary diagnosis. The lack of evidence regarding concordance between diagnoses rendered by WSI and LM is a significant barrier to both regulatory approval and uptake., Objective: -To examine the published literature on the concordance of pathologic diagnoses rendered by WSI compared with those rendered by LM., Data Sources: -We conducted a systematic review of studies assessing the concordance of pathologic diagnoses rendered by WSI and LM. Studies were identified following a systematic search of Medline (Medline Industries, Mundelein, Illinois), Medline in progress (Medline Industries), EMBASE (Elsevier, Amsterdam, the Netherlands), and the Cochrane Library (Wiley, London, England), between 1999 and March 2015., Conclusions: -Thirty-eight studies were included in the review. The mean diagnostic concordance of WSI and LM, weighted by the number of cases per study, was 92.4%. The weighted mean κ coefficient between WSI and LM was 0.75, signifying substantial agreement. Of the 30 studies quoting percentage concordance, 18 (60%) showed a concordance of 90% or greater, of which 10 (33%) showed a concordance of 95% or greater. This review found evidence to support a high level of diagnostic concordance. However, there were few studies, many were small, and they varied in quality, suggesting that further validation studies are still needed.