Tenets for the Proper Conduct and Use of Meta-Analyses: A Practical Guide for Neurosurgeons

Challenges and limitations in meta-analyses of complications in neurosurgery: Systematic review with proposed approach and checklist to mitigate errors and improve the assessment of the real-world experience

Meta-analyses are highly valued in medical science, yet accurately reporting complications in neurosurgical studies remains challenging. Examples include inconsistencies in defining and classifying complications and variations in reporting methods. This lack of reproducibility and comparability, along with other issues related to biases, hinders the ability of meta-analyses to yield significant advancements. This systematic review investigated the challenges and limitations inherent in meta-analyses of complications in neurosurgery. Based on the identified challenges and our group's experience, we developed a practical checklist to mitigate and avoid common errors in meta-analyses of complications in neurosurgery.We searched PubMed, Embase, and Web of Science for studies addressing challenges in assessing complications in neurosurgery. The main findings were qualitatively synthesized to identify common challenges and limitations. The proposed checklist was developed using a modified Delphi technique. Eleven studies were included, uncovering heterogeneity and a lack of standardization regarding the classification of complications in neurosurgery across various authors and institutions. They suggested solutions such as implementing a more uniform classification system. Additionally, the NeuroComp Meta-Analysis Checklist was developed, comprising 23 items divided into 5 domains, with a practical approach and suggestions on how to deal with the challenges when meta-analyzing.We identified numerous challenges and concerns when assessing complications in the neurosurgical field. The NeuroComp Meta-Analysis Checklist incorporated methodologies and approaches we utilized in several previously published meta-analyses. While we acknowledge that the proposal cannot solve all the issues involved in comparing and meta-analyzing complications in neurosurgery, it has the potential to enhance the informativeness of future meta-analyses and help authors mitigate common errors. Ultimately, this tool has the potential to contribute to the advancement of accumulating real-world evidence in neurosurgical science.

Repetitive Transcranial Magnetic Stimulation for Motor Recovery After Stroke: A Systematic Review and Meta-Analysis of Randomized Controlled Trials With Low Risk of Bias

OBJECTIVES

Repetitive transcranial magnetic stimulation (rTMS) has shown promising results in enhancing motor recovery after stroke, but nuances regarding its use, such as the impact of the type and site of stimulation, are not yet established. We aimed to perform a systematic review and meta-analysis of randomized controlled trials (RCTs) with low risk of bias to investigate the effect of rTMS on motor recovery after both ischemic and hemorrhagic stroke.

MATERIALS AND METHODS

Three databases were searched systematically for all RCTs reporting comparisons between rTMS (including theta-burst stimulation) and either no stimulation or sham stimulation up to August 19, 2022. The primary outcome measure was the Fugl-Meyer Assessment for Upper Extremity (FMA-UE). Secondary outcome measures comprised the Action Research Arm Test, Box and Block Test, Modified Ashworth Scale for the wrist, and modified Rankin Scale (mRS).

RESULTS

A total of 37 articles reporting 48 unique comparisons were included. Pooled mean FMA-UE scores were significantly higher in the experimental group than the control group after intervention (MD = 5.4 [MD = 10.7 after correction of potential publication bias], p < 0.001) and at the last follow-up (MD = 5.2, p = 0.031). On subgroup analysis, the improvements in FMA-UE scores, both after intervention and at the last follow-up, were significant in the acute/subacute stage of stroke (within six months) and for patients with more severe baseline motor impairment. Both contralesional and ipsilesional stimulation yielded significant improvements in FMA-UE at the first assessment after rTMS but not at the last follow-up, while the improvements from bilateral rTMS only achieved statistical significance at the last follow-up. Among the secondary outcome measures, only mRS was significantly improved in the rTMS group after intervention (MD = -0.5, p = 0.013) and at the last follow-up (MD = -0.9, p = 0.001).

CONCLUSIONS

Current literature supports the use of rTMS for motor recovery after stroke, especially when done within six months and for patients with more severe stroke at baseline. Future studies with larger sample sizes may be helpful in clarifying the potential of rTMS in poststroke rehabilitation.

Literature reviews and global neurosurgery: a powerful way of doing more with less

INTRODUCTION

Neurosurgery is an intensely competitive field. With the USMLE Step 1 transitioning to a pass/fail system, research has become a crucial component of the neurosurgery residency application process. This emphasis on research is particularly critical for international medical graduates (IMGs), who often face greater challenges compared to their U.S. counterparts. IMGs typically need more publications and higher H-indices to stand out. However, accessing quality research opportunities is significantly more difficult for those from low- and middle-income countries. This mini-review aims to provide a new perspective for IMGs, demonstrating that publishing in prestigious neurosurgical journals is possible even with limited resources.

METHODS

We searched Scopus and reviewed Brazilian publications from 2014 to 2023 in Neurosurgery and the Journal of Neurosurgery. We extracted the methodological designs of the studies and the graduation status of the first authors.

RESULTS

In 2023-2024, four Brazilian medical students published systematic reviews in major neurosurgical journals as first authors, marking a revolutionary change in the Brazilian neurosurgical landscape not seen in the past decade. These achievements illustrate that high-impact publications are attainable without geographical proximity, substantial financial support, or access to extensive institutional databases. Letters to the editor also represented a considerable Brazilian contribution.

CONCLUSION

Literature reviews and letters to the editor are accessible methods for IMGs to engage in impactful research. IMGs can maximize their abilities and significantly contribute to neurosurgery by embracing literature reviews and meta-analyses. These approaches can open doors for those without other avenues to begin their research careers.

Seniority of Surgeon in Chronic Subdural Hematoma Recurrence: A Systematic Review and Meta-analysis

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.

Systematic reviews and meta-analyses in neurosurgery Part II: a guide to designing the protocol

Despite clearly established guidelines, recent audits have found the conduct and reporting of systematic reviews and meta-analyses (SRMAs) within neurosurgery to be relatively lackluster in methodological rigor and compliance. Protocols of SRMAs allow for planning and documentation of review methods, guard against arbitrary decision-making during the review process, and enable readers to assess for the presence of selective reporting. To aid transparency, authors should provide sufficient detail in their protocol so that the readers could reproduce the study themselves. Development of our guideline drew heavily from the Preferred Reporting Items for Systematic Reviews and Meta-analyses Protocols (PRISMA-P) initiative. The objective of this article is not to enumerate every detail of this checklist, but to provide guidance to authors preparing their protocol, with examples, for a systematic review in neurosurgery. Particularly, we emphasize on the PICO framework - population (P), interventions (I), comparators (C), outcomes (O) - which is central to constructing a clinical question, defining the scope of the systematic review, defining and prioritizing the primary outcome, to specifying the eligibility criteria, designing the search strategy, and identifying potential sources of heterogeneity. We encourage our readers to make use of this guideline alongside the PRISMA-P 2015 statement, when drafting and appraising systematic review protocols.

Systematic reviews and meta-analyses in neurosurgery part I: interpreting and critically appraising as a guide for clinical practice

Neurosurgeons are inundated with the Herculean task to keep abreast with the rapid pace at which clinical research is proliferating. Systematic reviews and meta-analyses (SRMAs) have consequently surged in popularity because when executed properly, they constitute the highest level of evidence, and may save busy neurosurgeons many hours of combing the literature. Well-executed SRMAs may prove instructive for clinical practice, but poorly conducted reviews sow confusion and may potentially cause harm. Unfortunately, many SRMAs within neurosurgery are relatively lackluster in methodological rigor. When neurosurgeons apply the results of an SRMA to patient care, they should start by evaluating the extent to which the employed methods have likely protected against misleading results. The present article aims to educate the reader about how to interpret an SRMA, to assess the potential relevance of its results in the special context of the neurosurgical patient population.

A guide to interpreting systematic reviews and meta-analyses in neurosurgery and surgery

INTRODUCTION

Systematic reviews (SRs) and meta-analyses (MAs) are methods of data analysis used to synthesize information presented in multiple publications on the same topic. A thorough understanding of the steps involved in conducting this type of research and approaches to data analysis is critical for appropriate understanding, interpretation, and application of the findings of these reviews.

METHODS

We reviewed reference texts in clinical neuroepidemiology, neurostatistics and research methods and other previously related articles on meta-analyses (MAs) in surgery. Based on existing theories and models and our cumulative years of expertise in conducting MAs, we have synthesized and presented a detailed pragmatic approach to interpreting MAs in Neurosurgery.

RESULTS

Herein we have briefly defined SRs sand MAs and related terminologies, succinctly outlined the essential steps to conduct and critically appraise SRs and MAs. A practical approach to interpreting MAs for neurosurgeons is described in details. Based on summary outcome measures, we have used hypothetical examples to illustrate the Interpretation of the three commonest types of MAs in neurosurgery: MAs of Binary Outcome Measures (Pairwise MAs), MAs of proportions and MAs of Continuous Variables. Furthermore, we have elucidated on the concepts of heterogeneity, modeling, certainty, and bias essential for the robust and transparent interpretation of MAs. The basics for the Interpretation of Forest plots, the preferred graphical display of data in MAs are summarized. Additionally, a condensation of the assessment of the overall quality of methodology and reporting of MA and the applicability of evidence to patient care is presented.

CONCLUSION

There is a paucity of pragmatic guides to appraise MAs for surgeons who are non-statisticians. This article serves as a detailed guide for the interpretation of systematic reviews and meta-analyses with examples of applications for clinical neurosurgeons.

Incidence and Risk Factors of Surgical Site Infection After Cranial Surgery for Patients with Brain Tumors: A Systematic Review and Meta-analysis

BACKGROUND

Surgical site infections after craniotomy (SSI-CRANs) are a serious adverse event given the proximity of the wound to the central nervous system. SSI-CRANs are associated with substantial patient morbidity and mortality. Despite the importance and recognition of this event in other surgical fields, there is a paucity of evidence in the neurosurgical literature devoted to SSI-CRAN specifically in patients after brain tumor surgery.

METHODS

Systematic searches of Medline, Embase, and Cochrane Central were undertaken. The primary outcome was the incidence of SSI-CRAN at 30 and 90 days. Secondary outcomes were risk factors for SSI-CRAN.

RESULTS

Thirty-seven studies reporting 91,907 patients with brain tumors who underwent cranial surgery were included in the meta-analysis. Pooled incidence of SSI-CRAN at 30 and 90 days was 4.03% (95% CI: 2.94%-5.28%, I2 = 97.3) and 6.17% (95% CI: 3.16%-10.07%, I2 = 97.3), respectively. Specifically, incidence of SSI-CRAN following surgery for posterior fossa tumors was the highest at 9.67% (95% CI: 5.98%-14.09%, I2 = 75.5). Overall pooled incidence of readmission within 30 days and reoperation due to SSI-CRAN were 13.9% (95% CI: 12.5%-15.5%, I2 = 0.0) and 16.3% (95% CI: 5.4%-31.3%, I2 = 72.9), respectively. Risk factors for SSI-CRAN included reintervention (risk ratio [RR] 1.58, 95% CI: 1.22-2.04, I2 = 0.0), previous radiotherapy (RR 1.69, 95% CI: 1.20-2.38, I2 = 0.0), longer duration of operation (mean difference 64.18, 95% CI: 3.96-124.40 minutes, I2 = 90.3) and cerebrospinal fluid (CSF) leaks (RR 14.26, 95% CI: 2.14-94.90, I2 = 73.2).

CONCLUSIONS

SSI-CRAN affects up to 1 in 14 patients with brain tumors. High-risk groups include those with reintervention, previous radiotherapy, longer duration of operation, and CSF leaks. Further prospective studies should focus on bundles of care that will reduce SSI-CRAN.

Impact of Pretransplant Diabetes on Outcomes After Liver Transplantation: An Updated Meta-analysis With Systematic Review

BACKGROUND

Preliver transplant diabetes mellitus (pre-LT DM) is a common comorbidity in LT recipients associated with poorer post-transplant survival. However, its relationship with other important outcomes, including cardiovascular and renal outcomes, remains unclear. This meta-analysis aims to provide an updated analysis of the impact of pre-LT DM on key post-LT outcomes.

METHODS

A search was conducted in Medline and Embase databases for articles comparing the post-transplant outcomes between patients with and without pre-LT DM. Pairwise analysis using random effects with hazard ratios (HRs) was used to assess the longitudinal post-LT impacts of pre-LT DM. In the absence of HR, pooled odds ratios analysis was conducted for secondary outcomes.

RESULTS

Forty-two studies involving 77,615 LT recipients were included in this analysis. The pooled prevalence of pre-LT DM amongst LT recipients was 24.79%. Pre-LT DM was associated with significantly lower overall survival (HR, 0.65; 95% confidence interval, 0.52-0.81; P <0.01) and significantly increased cardiovascular disease-related mortality (HR, 1.78; 95% confidence interval, 1.11-2.85; P =0.03). Meta-regression of other patient characteristics identified Asian ethnicity and hypertension to be significant predictors of worse overall survival, whereas African-American ethnicity was associated with significantly improved overall survival in patients with pre-LT DM. Further analysis of secondary outcomes revealed pre-LT DM to be a significant predictor of post-LT cardiovascular events and end-stage renal disease.

CONCLUSIONS

The present study illustrates the impact of pre-LT DM on post-LT survival, and cardiovascular and renal outcomes and provides a sound basis for revision of preoperative management of pre-LT DM.

The incidence of adverse outcome in donors after living donor liver transplantation: A meta-analysis of 60,829 donors

The scarcity of liver grafts has prompted developments in living donor liver transplantations (LDLT), with previous literature illustrating similar outcomes in recipients compared to deceased donor transplants. However, significant concerns regarding living donor morbidity and mortality have yet to be examined comprehensively. This study aims to provide estimates of the incidence of various outcomes in living liver donors. In this meta-analysis, Medline and Embase were searched from inception to July 2022 for articles assessing the incidence of outcomes in LDLT donors. Complications in the included studies were classified into respective organ systems. Analysis of incidence was conducted using a generalized linear mixed model with Clopper-Pearson intervals. Eighty-seven articles involving 60,829 living liver donors were included. The overall pooled incidence of complications in LDLT donors was 24.7% (CI: 21.6%-28.1%). The incidence of minor complications was 17.3% (CI: 14.7%-20.3%), while the incidence of major complications was lower at 5.5% (CI: 4.5%-6.7%). The overall incidence of donor mortality was 0.06% (CI: 0.0%-0.1%) in 49,027 individuals. Psychological complications (7.6%, CI: 4.9%-11.5%) were the most common among LDLT donors, followed by wound-related (5.2%, CI: 4.4%-6.2%) and respiratory complications (4.9%, CI: 3.8%-6.3%). Conversely, cardiovascular complications had the lowest incidence among the subgroups at 0.8% (CI: 0.4%-1.3%). This study presents the incidence of post-LDLT outcomes in living liver donors, illustrating significant psychological, wound-related, and respiratory complications. While significant advancements in recent decades have contributed towards decreased morbidity in living donors, our findings call for targeted measures and continued efforts to ensure the safety and quality of life of liver donors post-LDLT.

The safety of early pharmacological venous thromboembolism prophylaxis in patients with traumatic intracranial haemorrhage: a systematic review and meta-analysis

INTRODUCTION

In patients with traumatic intracranial haemorrhage (tICH) there is significant risk of both venous thromboembolism (VTE) and haemorrhage progression. There is a paucity of literature to inform the timing of pharmacological thromboprophylaxis (PTP) initiation.

AIM

This meta-analysis aims to summarise the current literature on the timing of PTP initiation in tICH.

METHODS

This meta-analysis followed the Methodological Expectations of Cochrane Intervention Reviews checklist and the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. Following the literature search, studies were matched against the criteria for inclusion. Data from included studies was pooled, analysed using random-effect analysis and presented as forest plots of risk ratios, except one result reported as difference of means. The ROBINS-I tool was used to assess the risk of bias in the studies. The GRADE approach was taken to assess the quality of included studies. Heterogeneity of studies was assessed using Tau∧2. Funnel plots were generated and used in conjunction with Harbord's test and Rucker's arcsine to assess for small-study effect including publication bias.

RESULTS

A total of 9927 ICH patients who received PTP were included from 15 retrospective observational cohort studies, 4807 patients received early PTP, the remaining 5120 received late PTP. The definition of early was dependent on the study but no more than 72-hours after admission. The mean age of the included cohort was 45.3 (std dev ±9.5) years, and the proportion of males was 71%. Meta-analysis indicated that there was a significant difference between early and late groups for the rate of VTE (RR, 0.544; p = 0.000), pulmonary embolus (RR, 0.538; p = 0.004), deep vein thrombosis (RR, 0.484; p = 0.000) and the intensive care unit length of stay (difference of means, -2.021; 95% CI, -2.250, -1.792; p = 0.000; Tau∧2 = 0.000), favouring the early group. However, the meta-analysis showed no significant difference between the groups for the rate of mortality (RR, 1.008; p = 0.936), tICH progression (RR, 0.853; p = 0.157), and neurosurgical intervention (RR, 0.870; p = 0.480).

CONCLUSION

These findings indicated that early PTP appears to be safe and effective in patients with tICH.

Effectiveness of Cerebrospinal Fluid Lumbar Drainage Among Patients with Aneurysmal Subarachnoid Hemorrhage: An Updated Systematic Review and Meta-Analysis

INTRODUCTION

Cerebral vasospasm in patients after aneurysmal subarachnoid hemorrhage (aSAH) continues to be a major source of morbidity despite significant clinical and basic science research. The removal of blood and its degradation products from the subarachnoid space through prophylactic lumbar drainage (LD) is a favorable option. However, several studies have delivered conflicting conclusions on its efficacy after aSAH.

METHODS

Systematic searches of Medline, Embase, and Cochrane Central Register of Controlled Trials were performed. The primary outcome was a good functional outcome (modified Rankin scale score, 0-2). Secondary outcomes included symptomatic vasospasm, secondary cerebral infarction, and mortality.

RESULTS

A total of 14 studies reporting on 2473 patients with aSAH were included in the meta-analysis. Compared with the non-LD group, no significant differences were found in the rates of good functional outcomes in the LD group at discharge to 1 month (risk ratio [RR], 1.28; 95% confidence interval [CI], 0.64-2.58) or at 6 months (RR, 1.12; 95% CI, 0.97-1.41). These findings were consistent in the subgroup analyses of only randomized controlled trials or observational studies. LD was associated with lower rates of symptomatic vasospasm (RR, 0.61; 95% CI, 0.48-0.77), secondary cerebral infarction (RR, 0.59; 95% CI, 0.45-0.79), and mortality at discharge to 1 month (RR, 0.58; 95% CI, 0.41-0.82). The effect on mortality diminished at 6 months (RR, 0.70; 95% CI, 0.34-1.45). However, when analyzing only randomized controlled trials, the benefit of LD on lower rates of mortality continued even at 6 months (RR, 0.75; 95% CI, 0.58-0.99).

CONCLUSIONS

For aSAH patients, the use of LD is associated with benefits in the rates of vasospasm, secondary cerebral infarctions, and mortality, without an increased risk of adverse events.

Neurosurgical clipping versus endovascular coiling for patients with ruptured anterior circulation aneurysms: A systematic review and meta-analysis

To compare the safety and efficacy of clipping and coiling in patients with ruptured anterior circulation aneurysms. A systematic search of four databases (PubMed, Web of Science, Cochrane Library, and Embase) was conducted to identify comparative articles on endovascular coiling and surgical clipping in patients with ruptured anterior circulation aneurysms. Meta-analyses were conducted using random-effects models. Nineteen studies, including 1983 patients, were included. The meta-analysis showed that neurosurgical clipping was associated with a lower incidence of retreatment (OR:0.28, 95% CI (0.11, 0.70), P = 0.006) than endovascular coiling, which seemed to be a result of incomplete occlusion (OR:0.22, 95% CI (0.11, 0.45), P < 0.001). Neurosurgical clipping was associated with lower mortality (OR:0.45, 95% CI (0.25, 0.82), P = 0.009) at short-term follow-up than endovascular coiling. However, neurosurgical clipping showed a higher incidence of ischemic infarction (OR:2.28, 95% CI (1.44, 3.63), P < 0.001) and a longer length of stay (LOS) (WMD:6.12, 95% CI (4.19, 8.04), P < 0.001) after surgery than endovascular coiling. Furthermore, the pooled results showed no statistically significant differences between the two groups regarding poor outcome, long-term mortality, rebleeding, vasospasm, and hydrocephalus. Evidence from this systematic review illustrates that neurosurgical clipping may be superior to endovascular coiling for ruptured anterior circulation aneurysms. Large-scale RCTs should be conducted to verify these outcomes and provide results according to patient status.

Proton Pump Inhibitors Increases Longitudinal Risk of Mortality, Decompensation, and Infection in Cirrhosis: A Meta-Analysis

BACKGROUND/AIMS

Proton pump inhibitors (PPIs) are frequently prescribed to cirrhotic patients, but there is limited longitudinal evidence regarding their effects. This study aimed to assess the impact of PPIs on adverse events in cirrhotic patients.

METHODS

A comprehensive search was conducted using the Medline and Embase databases to identify relevant articles. Pooled hazard ratios (HRs) using DerSimonian and Laird random-effects model were calculated to evaluate the risk of adverse events such as long-term mortality, hepatic decompensation, hepatic encephalopathy (HE), spontaneous bacterial peritonitis (SBP), and overall infection in cirrhotic patients with PPI use.

RESULTS

The analysis included 28 studies with 260,854 cirrhotic patients. The prevalence of PPI use among cirrhotic patients was 55.93%. The use of PPIs was not significantly associated with short-term mortality in cirrhotic patients. However, long-term mortality (HR 1.321, 95% CI 1.103-1.581, P = 0.002), decompensation (HR 1.646, 95% CI 1.477-1.835, P < 0.001), HE (HR 1.968, 95% CI 1.372-2.822, P < 0.001), SBP (HR 1.751, 95% CI 1.649-1.859, P < 0.001), and infection (HR 1.370, 95% CI 1.148-1.634, P < 0.001) were significantly associated with PPI use. Sensitivity analysis with prospective studies yielded similar results.

CONCLUSION

PPIs should be reserved for appropriate indications at lowest effective dose for cirrhotic patients due to the potential harm.

Genomic Alterations and the Incidence of Brain Metastases in Advanced and Metastatic NSCLC: A Systematic Review and Meta-Analysis

INTRODUCTION

Brain metastases (BMs) in patients with advanced and metastatic NSCLC are linked to poor prognosis. Identifying genomic alterations associated with BM development could influence screening and determine targeted treatment. We aimed to establish prevalence and incidence in these groups, stratified by genomic alterations.

METHODS

A systematic review and meta-analysis compliant with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses were conducted (PROSPERO identification CRD42022315915). Articles published in MEDLINE, EMBASE, and Cochrane Library between January 2000 and May 2022 were included. Prevalence at diagnosis and incidence of new BM per year were obtained, including patients with EGFR, ALK, KRAS, and other alterations. Pooled incidence rates were calculated using random effects models.

RESULTS

A total of 64 unique articles were included (24,784 patients with NSCLC with prevalence data from 45 studies and 9058 patients with NSCLC having incidence data from 40 studies). Pooled BM prevalence at diagnosis was 28.6% (45 studies, 95% confidence interval [CI]: 26.1-31.0), and highest in patients that are ALK-positive (34.9%) or with RET-translocations (32.2%). With a median follow-up of 24 months, the per-year incidence of new BM was 0.13 in the wild-type group (14 studies, 95% CI: 0.11-0.16). Incidence was 0.16 in the EGFR group (16 studies, 95% CI: 0.11-0.21), 0.17 in the ALK group (five studies, 95% CI: 0.10-0.27), 0.10 in the KRAS group (four studies, 95% CI: 0.06-0.17), 0.13 in the ROS1 group (three studies, 95% CI: 0.06-0.28), and 0.12 in the RET group (two studies, 95% CI: 0.08-0.17).

CONCLUSIONS

Comprehensive meta-analysis indicates a higher prevalence and incidence of BM in patients with certain targetable genomic alterations. This supports brain imaging at staging and follow-up, and the need for targeted therapies with brain penetrance.

Deep brain stimulation for chronic pain: a systematic review and meta-analysis

Background

Deep brain stimulation (DBS) has shown promise in effectively treating chronic pain. This study aimed to assess the efficacy of DBS in this context.

Methods

We conducted a systematic literature search using PubMed, Scopus, and Web of Science, following the PRISMA guidelines. A well-constructed search strategy was utilized. Our literature search identified two groups of subjects: one group underwent DBS specifically for chronic pain treatment (DBS-P), while the second group received DBS for other indications (DBS-O), such as Parkinson's disease or dystonia, with pain perception investigated as a secondary outcome in this population. Meta-analysis was performed using R version 4.2.3 software. Heterogeneity was assessed using the tau^2 and I^2 indices, and Cochran's Q-test was conducted.

Results

The analysis included 966 patients in 43 original research studies with chronic pain who underwent DBS (340 for DBS-P and 625 for DBS-O). Subgroup analysis revealed that DBS-P exhibited a significant effect on chronic pain relief, with a standardized mean difference (SMD) of 1.65 and a 95% confidence interval (CI) of [1.31; 2.00]. Significant heterogeneity was observed among the studies, with an I^2 value of 85.8%. However, no significant difference was found between DBS-P and DBS-O subgroups. Subgroup analyses based on study design, age, pain diseases, and brain targets demonstrated varying levels of evidence for the effectiveness of DBS across different subgroups. Additionally, meta-regression analyses showed no significant relationship between age or pain duration and DBS effectiveness for chronic pain.

Conclusion

These findings significantly contribute to the expanding body of knowledge regarding the utility of DBS in the management of chronic pain. The study underscores the importance of conducting further research to enhance treatment outcomes and elucidate patient-specific factors that are associated with treatment response.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=428442, identifier CRD42023428442.

Oncologic outcomes after breast-conserving surgery with radiotherapy versus mastectomy in patients with Paget's disease of the breast: systematic review and meta-analysis

BACKGROUND

The conventional approach to treatment for Paget's disease of the breast has been mastectomy, but there is an increasing trend to consider breast-conserving surgery (BCS) followed by radiotherapy (RT) in these patients. This study aimed to provide an updated systematic review and meta-analysis comparing outcomes after BCS with RT versus mastectomy in the treatment of Paget's disease of the breast.

METHODS

Studies before May 2021 were included. Primary outcomes were overall survival and local recurrence. Separate analyses of Paget's disease associated with ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC) were undertaken. Meta-regression was used to adjust for imbalance in the proportion of IDC among patients selected to undergo BCS versus mastectomy.

RESULTS

Overall survival in patients with Paget's disease who underwent BCS with RT was higher than for those who underwent mastectomy with pooled mortality hazard ratio (HR) of 0.68, (95% per cent c.i. 0.45 to 1.01). Patients with Paget's disease with DCIS had higher overall survival after BCS with or without RT versus mastectomy, with adjusted HR of 0.14 (0.10 to 0.20) and 0.28 (0.22 to 0.36), respectively. For patients with Paget's disease and IDC, overall survival was lower for BCS with or without RT versus mastectomy, with adjusted HR of 0.84 (0.57 to 1.25) and 1.64 (1.04 to 2.58), respectively. In Paget's disease and IDC, local recurrence risk was much higher for BCS with RT, RR 26.8 (1.60 to 456) versus without RT, RR 51.8 (6.80 to 391). In patients with Paget's disease and DCIS, risk of local recurrence versus mastectomy was lower for BCS with RT 0.72 (0.11 to 4.50) but slightly higher for BCS alone 1.38 (0.09 to 21.20).

CONCLUSION

BCS with RT may be a comparable treatment alternative to mastectomy for patients with Paget's disease with DCIS, and for selected patients with Paget's disease and IDC.

Bridging thrombolysis improves survival rates at 90 days compared with direct mechanical thrombectomy alone in acute ischemic stroke due to basilar artery occlusion: a systematic review and meta-analysis of 1096 patients

BACKGROUND

Mechanical thrombectomy (MT) is an effective treatment for patients with acute ischemic stroke (AIS) from basilar artery occlusion (BAO).

OBJECTIVE

To compare the clinical outcomes of MT, with and without bridging intravenous thrombolysis (IVT), in acute BAO through a systematic review and meta-analysis of the current literature.

METHODS

Systematic searches of Medline, EMBASE, and Cochrane Central were undertaken on August 1, 2022. Good functional outcome defined as 90-day modified Rankin Scale score 0-2 was the primary outcome measure. Secondary outcome measures were 90-day mortality, successful post-thrombectomy recanalization (modified Thrombolysis in Cerebral Infarction score ≥2b), symptomatic intracranial hemorrhage (sICH), and subarachnoid hemorrhage (SAH).

RESULTS

Three studies reporting 1096 patients with BAO AIS were included in the meta-analysis. No significant differences in good functional outcome were detected between the two groups (RR=1.28 (95% CI 0.86 to 1.92); p=0.117). However, specifically patients with large artery atherosclerosis (LAA) benefited from bridging IVT (OR=2.52 (95% CI 1.51 to 4.22); p<0.001) with better functional outcomes. There was a significantly lower 90-day mortality rate for patients who underwent bridging IVT compared with MT alone (RR=0.70 (95% CI 0.62 to 0.80); p=0.008). No significant differences were detected in rates of post-treatment recanalization (RR=1.01 (95% CI 0.35 to 2.91); p=0.954), sICH (RR=0.96 (95% CI 0.66 to 1.42); p=0.724), and SAH (RR=0.93 (95% CI 0.31 to 2.83); p=0.563).

CONCLUSIONS

In patients with AIS due to BAO, bridging IVT was associated with lower mortality rates at 90 days, compared with direct MT. There were no improved functional outcomes or increased sICH or SAH between both arms, However, patients with LAA benefited from bridging IVT, with better functional outcomes.

Antiplatelet therapy in aneurysmal subarachnoid hemorrhage: an updated meta-analysis

Antiplatelet therapy (AT) may serve to reduce the effects of aneurysmal subarachnoid hemorrhage (aSAH)-induced pro-coagulant state in the cerebral circulation. Several studies, however, have delivered conflicting conclusions on the efficacy of AT post aSAH. Systematic searches of Medline, Embase, and Cochrane Central were undertaken on 27th March 2023. The primary outcome was delayed cerebral ischaemia (DCI). Secondary outcomes were symptomatic and angiographic vasospasm, good functional outcome (modified Rankin Scale [mRS] with scores 0-2), hemorrhagic events, and in-hospital mortality. Twenty-two studies reporting 4378 patients with aSAH were included in the meta-analysis. AT was associated with lower rates of DCI (RR=0.62, 95% CI: 0.43; 0.89), symptomatic vasospasm (RR=0.63, 95% CI: 0.46; 0.86), and moderate/severe angiographic vasospasm (RR=0.74, 95% CI: 0.65; 0.84), with no effect on hemorrhagic complications (RR=1.36, 95% CI: 0.77; 2.41). When analyzing only post-ictal use of AT, AT additionally favored rates of good functional outcomes (RR=1.18, 95% CI: 1.10; 1.26) and in-hospital mortality (RR=0.56, 95% CI: 0.39; 0.80). In the subgroup treated with cilostazol, AT was associated with lower rates of DCI (RR=0.40, 95% CI: 0.32), symptomatic vasospasm (RR=0.47, 95% CI: 0.33; 0.65), moderate/severe angiographic vasospasm (RR=0.75, 95% CI: 0.57; 0.98) and good functional outcome (RR=1.24, 95% CI: 1.08; 1.43). In the surgically treated aSAH subgroup, AT favored rates of symptomatic vasospasm (RR=0.55, 95% CI: 0.30; 0.98), moderate/severe angiographic vasospasm (RR=0.70, 95% CI: 0.54; 0.90) and good functional outcome (RR=1.23, 95% CI: 1.09; 1.41). In the endovascularly treated aSAH subgroup, AT was associated with lower rates of in-hospital mortality (RR=0.60, 95% CI: 0.41; 0.88). In aSAH patients, post-ictal AT is associated with benefits in terms of rates of DCI, vasospasm, good functional outcomes, and in-hospital mortality without an increased risk of hemorrhagic events.

Long-Standing Overt Ventriculomegaly in Adults: A Systematic Review and Meta-Analysis of Endoscopic Third Ventriculostomy Versus Ventriculoperitoneal Shunt as First-Line Treatment

BACKGROUND

Long-standing overt ventriculomegaly in adults (LOVA) is a heterogeneous term describing forms of adult hydrocephalus. LOVA incidence is increasing, yet the optimal treatment strategy for symptomatic cases remains unclear. We compared success rates and complication rates between endoscopic third ventriculostomy (ETV) and ventriculoperitoneal shunt (VPS) as first-line treatment for LOVA.

METHODS

A systematic review and meta-analysis was conducted in accordance with PRISMA guidelines. Three databases were searched, and articles published from 2000 to October 2022 were included (last search date October 24, 2022). Success rates and complications of both ETV and VPS were compared using random-effects models.

RESULTS

Of 895 articles identified, 22 studies were included in the analysis (556 patients: 346 in ETV group, 210 in VPS group). Mean age was 44.8 years. The most common presenting symptoms were gait disturbance (n = 178), headache (n = 156), and cognitive decline (n = 134). Combined success rates were 81.8% (n = 283/346) in the ETV group and 86.7% (n = 182/210) in the VPS group (median follow-up 41 months). There was no difference in success rates between ETV and VPS groups (odds ratio 0.94, 95% confidence interval 0.86-1.03, I2 = 0%). Combined complication rates were 4.6% (n = 16/346) in the ETV group and 27.1% (n = 57/210) in the VPS group. ETV had a lower rate of postoperative complications (odds ratio 0.22, 95% confidence interval 0.11-0.33, I2 = 0%).

CONCLUSIONS

Symptomatic LOVA can be successfully managed with surgical intervention. ETV and VPS have similar success rates when used as first-line treatment. VPS has a higher complication rate.

Surgical revascularizations for pediatric moyamoya: a systematic review, meta-analysis, and meta-regression analysis

INTRODUCTION

There is no clear consensus regarding the technique of surgical revascularization for moyamoya disease and syndrome (MMD/MMS) in the pediatric population. Previous meta-analyses have attempted to address this gap in literature but with methodological limitations that affect the reliability of their pooled estimates. This meta-analysis aimed to report an accurate and transparent comparison between studies of indirect (IB), direct (DB), and combined bypasses (CB) in pediatric patients with MMD/MMS.

METHODS

In accordance with PRISMA guidelines, systematic searches of Medline, Embase, and Cochrane Central were undertaken from database inception to 7 October 2022. Perioperative adverse events were the primary outcome measure. Secondary outcomes were rates of long-term revascularization, stroke recurrence, morbidity, and mortality.

RESULTS

Thirty-seven studies reporting 2460 patients and 4432 hemispheres were included in the meta-analysis. The overall pooled mean age was 8.6 years (95% CI: 7.7; 9.5), and 45.0% were male. Pooled proportions of perioperative adverse events were similar between the DB/CB and IB groups except for wound complication which was higher in the former group (RR = 2.54 (95% CI: 1.82; 3.55)). Proportions of post-surgical Matsushima Grade A/B revascularization favored DB/CB over IB (RR = 1.12 (95% CI 1.02; 1.24)). There was no significant difference in stroke recurrence, morbidity, and mortality. After meta-regression analysis, year of publication and age were significant predictors of outcomes.

CONCLUSIONS

IB, DB/CB are relatively effective and safe revascularization options for pediatric MMD/MMS. Low-quality GRADE evidence suggests that DB/CB was associated with better long-term angiographic revascularization outcomes when compared with IB, although this did not translate to long-term stroke and mortality benefits.

Placebo Adverse Events in Non-alcoholic Steatohepatitis Clinical Trials: A Pooled Analysis of 2,944 Participants

INTRODUCTION

In the absence of an effective treatment for non-alcoholic steatohepatitis (NASH), a randomized, placebo-controlled trial (RCT) remains the current gold standard study design in NASH. As NASH is a largely asymptomatic disease, the side effects of potential therapies require careful evaluation, therefore a pooled rate of the adverse events (AEs) in placebo-treated patients serves as a useful comparator for safety. Therefore, we performed a systematic review and meta-analysis to estimate the rate of AEs among participants in the placebo arm of NASH RCTs.

METHODS

Medline, Embase and Cochrane Central Register of Controlled Trials were searched to include clinical trials in phase 2-4 NASH RCTs with placebo treatment arms. A pooled proportions of AEs were analyzed using a generalized linear mixed model with Clopper-Pearson intervals.

RESULTS

A total of 41 RCTs (2,944 participants on placebo) were included in this meta-analysis. A total of 68% (confidence interval [CI] 55%-77%) of participants on placebo experienced an AE, 7.8% (5.7%-10%) experienced serious AEs and 3.1% (CI: 1.9%-5.1%) experienced AEs leading to discontinuation. A significantly higher proportion of participants experienced serious AEs in phase 3 studies compared to in phase 2 studies ( P < 0.01) and in pharmaceutical funded studies as compared to studies which were federal-funded studies ( P < 0.01). An analysis of clinical trials evaluating bile acid modulating agents determined that 10% (CI: 5.5%-18%) of participants receiving placebo developed pruritus.

DISCUSSION

The present study summarizes the AEs with NASH placebo. Among participants in the placebo arm in NASH, two-third experienced an AE, and nearly 10% experienced a serious AE.

Revisiting primary endocrine therapy versus surgery in older women with breast cancer: meta-analysis

BACKGROUND

Old age is associated with increased co-morbidities, resulting in reduced life expectancy. Primary endocrine therapy is an alternative to primary surgical therapy for patients with breast cancer and increased co-morbidities. The aim was to review outcomes of primary endocrine therapy versus primary surgical therapy in older women with breast cancer.

METHODS

PubMed, Embase (Ovid), Scopus, and the Cochrane Library were searched systematically from January 2000 to May 2022. Single-arm studies were excluded. Primary outcomes were overall survival and breast cancer-specific survival. Secondary outcomes were local and regional failure of primary endocrine therapy, recurrence after primary surgical therapy, and health-related quality of life.

RESULTS

There were 14 studies including 14 254 patients (primary endocrine therapy 2829, 19.8 per cent; primary surgical therapy 11 425, 80.2 per cent), with the addition of four major studies (9538 patients) compared with the latest review in 2014. Seven studies defined primary surgical therapy as surgery plus adjuvant endocrine therapy, and six studies included patients with oestrogen receptor-positive tumours only. Patients in the primary endocrine therapy group were older than the primary surgical therapy group (mean difference 2.43 (95 per cent c.i. 0.73 to 4.13) years). Primary endocrine therapy led to worse overall survival than primary surgical therapy (HR 1.42, 95 per cent c.i. 1.06 to 1.91). Subgroup analysis of RCTs and prospective studies, however, showed comparable overall survival. Breast cancer-specific survival was also comparable (HR 1.28, 95 per cent c.i. 0.87 to 1.87). At 6 weeks, operated patients had significant arm symptoms and illness burden following major breast surgery compared with patients receiving primary endocrine therapy. Health-related quality of life, measured by the European Organization for Research and Treatment of Cancer QLQ-C30 and EuroQol EQ-5D-5L™, was comparable in the two treatment groups.

CONCLUSION

Overall survival was worse among older women receiving primary endocrine therapy in an analysis including all studies, but comparable in RCTs and prospective studies. This may be due to confounding by age and co-morbidities in retrospective cohort studies of primary endocrine therapy.

Thromboembolic events in hospitalised patients with COVID-19: ecological assessment with a scoping review

OBJECTIVES

Thrombosis is a common complication of the novel COVID-19. Pre-COVID-19 studies reported racial differences in the risk of developing thrombosis. This study aimed to describe the geographical variations in the reported incidences and outcomes of thromboembolic events and thromboprophylaxis in hospitalised patients with COVID-19. The final search for randomised clinical trials was carried out in January 2022. Screening eligible articles and data extraction were independently performed in duplicate by multiple reviewers.

DESIGN

Scoping review. MEDLINE, Embase, Cochrane Libraries were searched using terms related to COVID-19 and thromboembolism.

SETTING

Hospitals all over the world.

PARTICIPANTS

In-hospital patients with COVID-19.

OUTCOME MEASURES

The incidence of deep venous thrombosis (DVT) and pulmonary embolism (PE), and the prophylactic anticoagulation therapy.

RESULTS

In total, 283 studies were eligible, representing (239 observational studies, 39 case series and 7 interventional studies). The incidence of DVT was the highest in Asia (40.8%) and hospital mortality was high (22.7%). However, the incidence of PE was not very high in Asia (3.2%). On the contrary, the incidence of PE was the highest in the Middle East (16.2%) and Europe (14. 6%). Prophylactic anticoagulation therapy with low-molecular-weight heparin was the main treatment provided in all areas. Four of the seven randomised clinical trials were conducted internationally.

CONCLUSIONS

The incidence of DVT was the highest in Asia. The incidence of PE was higher in the Middle East and Europe; however, detection bias during the pandemic cannot be ruled out. There were no major differences in the type or dose of prophylactic anticoagulants used for thromboprophylaxis among the regions.

A Meta-analysis on Associated Risk of Mortality in Nonalcoholic Fatty Liver Disease

OBJECTIVE

Nonalcoholic fatty liver disease (NAFLD) affects much of the worldwide population and poses a significant burden to the global healthcare. The rising numbers of individuals with NAFLD and instances of mortality point toward the importance of understanding the association causes of mortality in NAFLD. This meta-analysis aimed to seek the associations of NAFLD with all-cause, cardiovascular disease (CVD)-related, liver-related, and cancer-related mortality.

METHODS

MEDLINE and Embase were searched for articles relating to causes of mortality between NAFLD and non-NAFLD. The DerSimonian and Laird random-effects model was used to analyze adjusted hazard ratios (HR), and a sensitivity analysis was conducted to reduce heterogeneity through a graphical display of study heterogeneity.

RESULTS

Fifteen studies involving 10 286 490 patients were included. Individuals with NAFLD exhibited an increased risk of all-cause mortality (HR, 1.32; 95% CI, 1.09-1.59; P < .01; I² = 96.00%), CVD-related mortality (HR, 1.22; 95% CI, 1.06-1.41; P < .01; I² = 81.00%), and cancer-related mortality (HR, 1.67; 95% CI, 1.15-2.41; P < .01; I² = 95.00%). However, no significant association was found between liver-related mortality and NAFLD (HR, 3.58; 95% CI, 0.69-18.46; P =.13; I² = 96.00%). The sensitivity analysis conducted with graphic display of heterogeneity and only population-based studies found similar results.

CONCLUSION

NAFLD was associated with an increased risk of all-cause, CVD-related, and cancer-related mortality but not liver-related mortality. The finding is likely because of low fibrosis prevalence in the community. However, the significant burden in other causes of mortality beyond the liver points to a need for multidisciplinary efforts to reduce the mortality risks.

Seizure outcome after resection of insular glioma: a systematic review, meta-analysis, and institutional experience

OBJECTIVE

Gliomas arising from the insular cortex can be epileptogenic, with a significant proportion of patients having medically refractory epilepsy. The impact of surgery on seizure control for such tumors is not well established. In this study, the authors aimed to investigate seizure outcomes after resection of insular gliomas using a meta-analysis and institutional experience.

METHODS

Three databases (Ovid MEDLINE, Embase, and Cochrane Central Register of Controlled Trials) were systematically searched for published studies of seizure outcomes after insular glioma resection from database inception to March 27, 2021. In addition, data were retrospectively collected on all adults (age > 17 years) who had undergone insular glioma resection between June 1997 and June 2015 at the authors' institution. Primary outcome measures were seizure freedom rates at 1 year and the last follow-up. Secondary outcome measures consisted of persistent postoperative neurological deficit beyond 90 days, mortality, and tumor progression or recurrence.

RESULTS

Eight studies reporting on 453 patients who had undergone 460 operations were included in the meta-analysis. The pooled mean age of the patients was 42 years. The pooled percentages of patients with extents of resection (EORs) ≥ 90%, 70%-89%, and < 70% were 55%, 33%, and 11%, respectively. The pooled seizure freedom rate at 1 year was 73% for Engel class IA and 78% for Engel class I. The pooled seizure freedom rate at the last follow-up was 60% for Engel class IA and 79% for Engel class I. The pooled percentage of persistent neurological deficit beyond 90 days was 3%. At the authors' institution, 109 patients had undergone resection of insular glioma. A greater EOR was the only significant independent predictor of seizure freedom after surgery (HR 0.290, p = 0.017). The optimal threshold for seizure freedom corresponded to an EOR of 81%. Patients with an EOR > 81% had a significantly higher seizure freedom rate (OR 2.16, p = 0.048).

CONCLUSIONS

Maximal safe resection can be performed with minimal surgical morbidity to achieve favorable seizure freedom rates in both the short and long term. When gross-total resection is not possible, an EOR > 81% confers the greatest sensitivity and specificity for achieving seizure freedom. Systematic review registration no.: CRD42021249404 (https://www.crd.york.ac.uk/prospero/).

Global prevalence of depression and anxiety in patients with hepatocellular carcinoma: Systematic review and meta-analysis

BACKGROUND/AIMS

Depression and anxiety are associated with poorer outcomes in patients with hepatocellular carcinoma (HCC). However, the prevalence of depression and anxiety in HCC are unclear. We aimed to establish the prevalence of depression and anxiety in patients with HCC.

METHODS

MEDLINE and Embase were searched and original articles reporting prevalence of anxiety or depression in patients with HCC were included. A generalized linear mixed model with Clopper-Pearson intervals was used to obtain the pooled prevalence of depression and anxiety in patients with HCC. Risk factors were analyzed via a fractional-logistic regression model.

RESULTS

Seventeen articles involving 64,247 patients with HCC were included. The pooled prevalence of depression and anxiety in patients with HCC was 24.04% (95% confidence interval [CI], 13.99-38.11%) and 22.20% (95% CI, 10.07-42.09%) respectively. Subgroup analysis determined that the prevalence of depression was lowest in studies where depression was diagnosed via clinician-administered scales (16.07%;95% CI, 4.42-44.20%) and highest in self-reported scales (30.03%; 95% CI, 17.19-47.01%). Depression in patients with HCC was lowest in the Americas (16.44%; 95% CI, 6.37-36.27%) and highest in South-East Asia (66.67%; 95% CI, 56.68-75.35%). Alcohol consumption, cirrhosis, and college education significantly increased risk of depression in patients with HCC.

CONCLUSION

One in four patients with HCC have depression, while one in five have anxiety. Further studies are required to validate these findings, as seen from the wide CIs in certain subgroup analyses. Screening strategies for depression and anxiety should also be developed for patients with HCC.

Living in the non-alcoholic fatty liver disease silent epidemic: a qualitative systematic review of patients' perspectives

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) affects one-fourth of the global population. Yet, the care of these patients is limited and awareness of NAFLD remains low in the general public. Investigations into the lives of these patients are often forgotten and traditional quantitative studies only paint part of the picture.

AIM

To assess the first-hand accounts of these individuals and their perspective on living with NAFLD.

METHODS

A systematic search was conducted on Medline, Embase, CINAHL, PsycINFO and Web of Science database for qualitative literature regarding patients' perspectives on NAFLD. An inductive thematic analysis was conducted to generate themes and supportive subthemes.

RESULTS

We incuded eight articles in the review. There were three major themes including the impact on the quality of life, knowledge and information, and attitudes and perceptions on care. The impact of the quality of life details the emotional and physical distress of NAFLD. Knowledge and information include the lack of sufficient communication between healthcare providers and patients with a distinct knowledge gap. Attitudes and perceptions on care extrapolate the current active participation of patients and needs of the patients and the future care that they desire.

CONCLUSION

This review synthesises first-hand accounts of individuals with NAFLD. With the growing burden of NAFLD, future public interventions must consider individual views for success to be found. The identified themes serve as a forefront for consideration for public policies. Ultimately, NAFLD is a multisystem disease, which must be managed by a multidisciplinary team.

Comparative Burden of Metabolic Dysfunction in Lean NAFLD vs Non-lean NAFLD - A Systematic Review and Meta-analysis

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD) is traditionally associated with obesity. However, there is a subtype of NAFLD, namely NAFLD in lean, that occurs without obesity. However, a recent call to redefine NAFLD to metabolic-associated fatty liver disease focuses on obesity and metabolic dysfunction. Criticism has arisen from the perceived over emphasis on systemic comorbidities, which may disadvantage the lean. The current analysis seeks to quantify the degree of metabolic dysfunction in NAFLD in lean and compare with NAFLD in overweight and obese and non-NAFLD.

METHODS

Medline and Embase databases were searched from inception to March 3, 2022. The inclusion criteria were articles with NAFLD in lean patients presenting with baseline metabolic parameters. Comparisons were conducted with subgroup analysis.

RESULTS

Eighty-five articles were included in the meta-analysis. NAFLD in lean accounted for 13.11% (95% confidence interval [CI], 10.26%-16.62%) of the global population and 14.55% (95% CI, 11.32%-18.51%) in Asia. The degree of metabolic dysfunction was weight dependent with significantly less metabolic dysfunction in NAFLD in lean subjects as compared with NAFLD in overweight counterparts. For NAFLD in lean, only 19.56% (95% CI, 15.28%-24.69%) of the subjects were diabetic, whereas 45.70% (95% CI, 35.01%-56.80%) of obese subjects with NAFLD had diabetes (P < .01). Fasting blood glucose and systolic and diastolic blood pressure values were significantly lower in subjects with NAFLD in lean than in overweight and obese.

CONCLUSION

The current analysis highlights the weight-dependent nature of metabolic dysfunction in NAFLD. Lean subjects with NAFLD were significantly less metabolically unhealthy than were obese and overweight persons with NAFLD. An overreliance on metabolic dysfunction in defining fatty liver will be a flaw in potentially excluding previously characterized NAFLD.