Saleh A. Almenawer

Endovascular Thrombectomy for Acute Ischemic Stroke: A Meta-analysis

IMPORTANCE Endovascular intervention for acute ischemic stroke improves revascularization. But trials examining endovascular therapy yielded variable functional outcomes, and the effect of endovascular intervention among subgroups needs better definition. OBJECTIVE To examine the association between endovascular mechanical thrombectomy and clinical outcomes among patients with acute ischemic stroke. DATA SOURCES We systematically searched MEDLINE, EMBASE, CINAHL, Google Scholar, and the Cochrane Library without language restriction through August 2015. STUDY SELECTION Eligible studies were randomized clinical trials of endovascular therapy with mechanical thrombectomy vs standard medical care, which includes the use of intravenous tissue plasminogen activator (tPA). DATA EXTRACTION AND SYNTHESIS Independent reviewers evaluated the quality of studies and abstracted the data. We calculated odds ratios (ORs) and 95% CIs for all outcomes using random-effects meta-analyses and performed subgroup and sensitivity analyses to examine whether certain imaging, patient, treatment, or study characteristics were associated with improved functional outcome. The strength of the evidence was examined for all outcomes using the GRADE method. MAIN OUTCOMES AND MEASURES Ordinal improvement across modified Rankin scale (mRS) scores at 90 days, functional independence (mRS score, 0-2), angiographic revascularization at 24 hours, symptomatic intracranial hemorrhage within 90 days, and all-cause mortality at 90 days. RESULTS Data were included from 8 trials involving 2423 patients (mean [SD] age, 67.4 [14.4] years; 1131 [46.7%] women), including 1313 who underwent endovascular thrombectomy and 1110 who received standard medical care with tPA. In a meta-analysis of these trials, endovascular therapy was associated with a significant proportional treatment benefit across mRS scores (OR, 1.56; 95% CI, 1.14-2.13; P = .005). Functional independence at 90 days (mRS score, 0-2) occurred among 557 of 1293 patients (44.6%; 95% CI, 36.6%-52.8%) in the endovascular therapy group vs 351 of 1094 patients (31.8%; 95% CI, 24.6%-40.0%) in the standard medical care group (risk difference, 12%; 95% CI, 3.8%-20.3%; OR, 1.71; 95% CI, 1.18-2.49; P = .005). Compared with standard medical care, endovascular thrombectomy was associated with significantly higher rates of angiographic revascularization at 24 hours (75.8% vs 34.1%; OR, 6.49; 95% CI, 4.79-8.79; P < .001) but no significant difference in rates of symptomatic intracranial hemorrhage within 90 days (70 events [5.7%] vs 53 events [5.1%]; OR, 1.12; 95% CI, 0.77-1.63; P = .56) or all-cause mortality at 90 days (218 deaths [15.8%] vs 201 deaths [17.8%]; OR, 0.87; 95% CI, 0.68-1.12; P = .27). CONCLUSIONS AND RELEVANCE Among patients with acute ischemic stroke, endovascular therapy with mechanical thrombectomy vs standard medical care with tPA was associated with improved functional outcomes and higher rates of angiographic revascularization, but no significant difference in symptomatic intracranial hemorrhage or all-cause mortality at 90 days.

Chronic Subdural Hematoma Management: A Systematic Review and Meta-analysis of 34829 Patients

Objective:To compare the efficacy and safety of multiple treatment modalities for the management of chronic subdural hematoma (CSDH) patients. Background:Current management strategies of CSDHs remain widely controversial. Treatment options vary from medical therapy and bedside procedures to major operative techniques. Methods:We searched MEDLINE (PubMed and Ovid), EMBASE, CINAHL, Google scholar, and the Cochrane library from January 1970 through February 2013 for randomized and observational studies reporting one or more outcome following the management of symptomatic patients with CSDH. Independent reviewers evaluated the quality of studies and abstracted the data on the safety and efficacy of percutaneous bedside twist-drill drainage, single or multiple operating room burr holes, craniotomy, corticosteroids as a main or adjuvant therapy, use of drains, irrigation of the hematoma cavity, bed rest, and treatment of recurrences following CSDH management. Mortality, morbidity, cure, and recurrence rates were examined for each management option. Randomized, prospective, retrospective, and overall observational studies were analyzed separately. Pooled estimates, confidence intervals (CIs), and relative risks (RRs) were calculated for all outcomes using a random-effects model. Results:A total of 34,829 patients from 250 studies met our eligibility criteria. Sixteen trials were randomized, and the remaining 234 were observational. We included our unpublished single center series of 834 patients. When comparing percutaneous bedside drainage to operating room burr hole evacuation, there was no significant difference in mortality (RR, 0.69; 95% CI, 0.46–1.05; P = 0.09), morbidity (RR, 0.45; 95% CI, 0.2–1.01; P = 0.05), cure (RR, 1.05; 95% CI, 0.98–1.11; P = 0.15), and recurrence rates (RR, 1; 95% CI, 0.66–1.52; P = 0.99). Higher morbidity was associated with the adjuvant use of corticosteroids (RR, 1.97; 95% CI, 1.54–2.45; P = 0.005), with no significant improvement in recurrence and cure rates. The use of drains following CSDH drainage resulted in a significant decrease in recurrences (RR, 0.46; 95% CI, 0.27–0.76; P = 0.002). Craniotomy was associated with higher complication rates if considered initially (RR, 1.39; 95% CI, 1.04–1.74; P = 0.01); however, craniotomy was superior to minimally invasive procedures in the management of recurrences (RR, 0.22; 95% CI, 0.05–0.85; P = 0.003). Conclusions:Percutaneous bedside twist-drill drainage is a relatively safe and effective first-line management option. These findings may result in potential health cost savings and eliminate perioperative risks related to general anesthetic.

Biopsy versus partial versus gross total resection in older patients with high-grade glioma: a systematic review and meta-analysis

BACKGROUND Optimal extent of surgical resection (EOR) of high-grade gliomas (HGGs) remains uncertain in the elderly given the unclear benefits and potentially higher rates of mortality and morbidity associated with more extensive degrees of resection. METHODS We undertook a meta-analysis according to a predefined protocol and systematically searched literature databases for reports about HGG EOR. Elderly patients (≥60 y) undergoing biopsy, subtotal resection (STR), and gross total resection (GTR) were compared for the outcome measures of overall survival (OS), postoperative karnofsky performance status (KPS), progression-free survival (PFS), mortality, and morbidity. Treatment effects as pooled estimates, mean differences (MDs), or risk ratios (RRs) with corresponding 95% confidence intervals (CIs) were determined using random effects modeling. RESULTS A total of 12 607 participants from 34 studies met eligibility criteria, including our current cohort of 211 patients. When comparing overall resection (of any extent) with biopsy, in favor of the resection group were OS (MD 3.88 mo, 95% CI: 2.14-5.62, P < .001), postoperative KPS (MD 10.4, 95% CI: 6.58-14.22, P < .001), PFS (MD 2.44 mo, 95% CI: 1.45-3.43, P < .001), mortality (RR = 0.27, 95% CI: 0.12-0.61, P = .002), and morbidity (RR = 0.82, 95% CI: 0.46-1.46, P = .514) . GTR was significantly superior to STR in terms of OS (MD 3.77 mo, 95% CI: 2.26-5.29, P < .001), postoperative KPS (MD 4.91, 95% CI: 0.91-8.92, P = .016), and PFS (MD 2.21 mo, 95% CI: 1.13-3.3, P < .001) with no difference in mortality (RR = 0.53, 95% CI: 0.05-5.71, P = .600) or morbidity (RR = 0.52, 95% CI: 0.18-1.49, P = .223). CONCLUSIONS Our findings suggest an upward improvement in survival time, functional recovery, and tumor recurrence rate associated with increasing extents of safe resection. These benefits did not result in higher rates of mortality or morbidity if considered in conjunction with known established safety measures when managing elderly patients harboring HGGs.

Levels of evidence in the neurosurgical literature: more tribulations than trials.

BACKGROUND The importance of evidence-based medicine has been well documented and supported across various surgical subspecialties. OBJECTIVE To quantify the levels of evidence across publications in the neurosurgical literature, to assess the change in evidence over time, and to indicate predictive factors of higher-level evidence. METHODS We reviewed the levels of evidence across published clinical studies in 3 neurosurgical journals from 2009 to 2010. Randomized trials were evaluated by use of the Detsky quality of reporting scale. Levels-of-evidence data for the same journals in 1999 were obtained from the literature, and regression analysis was performed to identify predictive factors for higher-level evidence. RESULTS Of 660 eligible articles, 14 (2.1%) were Level I, 54 (8.2%) were level II, 73 (11.1%) were Level III, 287 (43.5%) were level IV, and 232 (35.2%) were level V. The number of level I studies decreased significantly between 1999 and 2010 (3.4% vs. 2.1%, respectively; P = .01). Seven randomized clinical trials were identified, and 1 trial had significant methodological limitations (mean Detsky index = 16.3; SD = 1.8). Publications with larger sample size were significantly associated with higher levels of evidence (levels I and II; odds ratio, 1.7; 95% confidence interval, 1.45-2.05; P = .001). The ratio of higher levels of evidence to lower levels was 0.11. CONCLUSION Higher levels of evidence (levels I and II) represent only 1 in 10 neurosurgical clinical papers in the top neurosurgical journals. Increased awareness of the need for better evidence in the field through education and adoption of the levels of evidence may improve the conduct and publication of prospective studies.

The value of scheduled repeat cranial computed tomography after mild head injury: single-center series and meta-analysis.

BACKGROUND After an initial computed tomography (CT) scan revealing intracranial hemorrhage resulting from traumatic brain injury, a standard of care in many trauma centers is to schedule a repeat CT scan to rule out possible progression of bleed. OBJECTIVE To evaluate the utility of routine follow-up CT in changing the management of mild head injury patients despite clinical stability, although repeat imaging is indicated to assess a deteriorating patient. METHODS The trauma database at our institution was retrospectively reviewed and the literature was searched to identify patients after mild head injury with positive initial CT finding and scheduled repeat scan. Patients were divided into 2 groups for comparison. Group A included patients who had intervention based on neurological examination changes. Group B comprised patients requiring a change in management according to CT results exclusively. The meta-analysis of the present cohort and included articles was performed with a random-effects model. RESULTS Overall, 15 studies and 445 patients met our eligibility criteria, totaling 2693 patients. Intervention rates of groups A and B were 2.7% (95% confidence interval, 1.7-3.9; P = .003) and 0.6% (95% confidence interval, 0.3-1; P = .21), respectively. The statistical difference between both intervention rates was clinically significant with P < .001. CONCLUSION The available evidence indicates that it is unnecessary to schedule a repeat CT scan after mild head injury when patients are unchanged or improving neurologically. In the absence of supporting data, we question the value of routine follow-up imaging given the associated accumulative increase in cost and risks.

Mortality and morbidity in acutely ill adults treated with liberal versus conservative oxygen therapy (IOTA): a systematic review and meta-analysis

BACKGROUND Supplemental oxygen is often administered liberally to acutely ill adults, but the credibility of the evidence for this practice is unclear. We systematically reviewed the efficacy and safety of liberal versus conservative oxygen therapy in acutely ill adults. METHODS In the Improving Oxygen Therapy in Acute-illness (IOTA) systematic review and meta-analysis, we searched the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, HealthSTAR, LILACS, PapersFirst, and the WHO International Clinical Trials Registry from inception to Oct 25, 2017, for randomised controlled trials comparing liberal and conservative oxygen therapy in acutely ill adults (aged ≥18 years). Studies limited to patients with chronic respiratory diseases or psychiatric disease, patients on extracorporeal life support, or patients treated with hyperbaric oxygen therapy or elective surgery were excluded. We screened studies and extracted summary estimates independently and in duplicate. We also extracted individual patient-level data from survival curves. The main outcomes were mortality (in-hospital, at 30 days, and at longest follow-up) and morbidity (disability at longest follow-up, risk of hospital-acquired pneumonia, any hospital-acquired infection, and length of hospital stay) assessed by random-effects meta-analyses. We assessed quality of evidence using the grading of recommendations assessment, development, and evaluation approach. This study is registered with PROSPERO, number CRD42017065697. FINDINGS 25 randomised controlled trials enrolled 16 037 patients with sepsis, critical illness, stroke, trauma, myocardial infarction, or cardiac arrest, and patients who had emergency surgery. Compared with a conservative oxygen strategy, a liberal oxygen strategy (median baseline saturation of peripheral oxygen [SpO2] across trials, 96% [range 94-99%, IQR 96-98]) increased mortality in-hospital (relative risk [RR] 1·21, 95% CI 1·03-1·43, I2=0%, high quality), at 30 days (RR 1·14, 95% CI 1·01-1·29, I2=0%, high quality), and at longest follow-up (RR 1·10, 95% CI 1·00-1·20, I2=0%, high quality). Morbidity outcomes were similar between groups. Findings were robust to trial sequential, subgroup, and sensitivity analyses. INTERPRETATION In acutely ill adults, high-quality evidence shows that liberal oxygen therapy increases mortality without improving other patient-important outcomes. Supplemental oxygen might become unfavourable above an SpO2 range of 94-96%. These results support the conservative administration of oxygen therapy. FUNDING None.

Cervical Spine Clearance in Obtunded Patients After Blunt Traumatic Injury: A Systematic Review

Cervical spine trauma is a major public health problem and a common reason for admission to trauma wards and intensive care units. The cervical spine is injured in 2.3% to 4.3% (14) of blunt traumas. Resultant neurologic impairment is encountered in 33% to 54% (57) of patients with cervical spine trauma. In fact, more than 50% of all acute spinal cord injuries affect the cervical spine (8, 9). Unfortunately, these injuries have poor functional outcomes. Mortality after traumatic cervical spinal cord injury may exceed 20% (1013), and survivors often face lifelong physical disability, along with the associated emotional, psychological, and social burdens (6, 8, 14, 15). The economic costs of spinal cord injury are enormous. In the United States, the total annual direct cost of spinal cord injuries approaches

Exploring predictors of surgery and comparing operative treatment approaches for pediatric intracranial arachnoid cysts: a case series of 83 patients

8 billion (16). These factors make diligent and efficient cervical spine clearance protocols a critical priority. The exclusion of cervical spine injury in obtunded patients with trauma poses a significant challenge given the lack of a reliable clinical examination. Common practices at many trauma centers include routine acquisition of cervical spine magnetic resonance imaging (MRI), dynamic radiography (flexion and extension), or continued cervical immobilization until patients are awake and asymptomatic after a negative computed tomography (CT) scan (17, 18). These protocols may increase health care costs unduly, place critically ill patients at risk for deterioration during transportation, and prolong cervical collar immobilization and its associated illnesses. On the other hand, the consequences of missing an injury can be devastating and may include loss of functional ability, independence, and possibly life (1921). The primary aim of this study was to elucidate the role for further routine imaging or prolonged cervical immobilization in excluding significant cervical spine injury after negative CT results in obtunded patients who had blunt traumatic injury. Methods This systematic review was done according to a predefined protocol (Supplement) in accordance with MOOSE (Meta-analysis Of Observational Studies in Epidemiology) guidelines (22) and the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) Statement (23). Supplement. Study Protocol Search Strategy We searched MEDLINE (PubMed and Ovid), EMBASE, CINAHL, Google Scholar, and the Cochrane Library from January 2000 through November 2014 for studies on the role of CT followed by a validating test in evaluating the cervical spine of obtunded trauma patients. We used, in various combinations, keywords and Medical Subject Headings terms pertinent to the patient population (altered, comatose, intensive care, intubated, mental status, obtunded, unconscious, unevaluable, unexaminable, unreliable, or unresponsive), medical condition (fracture, injury, instability, or trauma), anatomical site of interest (cervical-spine or cervical), and relevant radiological imaging methods (clearance, computed tomography, CT, dynamic, extension, flexion, fluoroscopy, imaging, magnetic resonance, MDCT, MR, MRI, plain film, radiograph, or X-ray). We also manually searched the references of relevant studies to identify additional studies for consideration. Selection Criteria Three investigators independently evaluated the studies for eligibility. Selection criteria included a study of any design (randomized, controlled trial; prospective cohort study; or retrospective cohort study). Studies were eligible if the diagnostic protocol of interest included a negative finding on a helical CT scan of the entire cervical spine followed by a confirmatory test. We included only the population of obtunded patients with blunt trauma (Glasgow Coma Scale [GCS] score 14, unreliable clinical examination, or intubation). Only English-language studies documenting the outcome measures of missed cervical spine injury or intervention after a negative CT result and additional findings of a validating test were included. We excluded studies with a sample size of fewer than 10 patients and studies in which partial cervical spine CT scans were used. For studies reporting data on overlapping cohorts from the same institution, we included only the study with the most inclusive cohort to prevent duplication. Studies evaluating only the pediatric population were excluded. Studies that examined awake and obtunded patients were included only if the outcomes of unreliable patients were analyzed separately. Abstracts from meeting proceedings were excluded if the data were not published in full-text articles in a peer-reviewed journal. Disagreements among the 3 reviewers about the decision to include or exclude a study were resolved by consensus and, if necessary, consultation with a fourth reviewer. Data Extraction and Quality Assessment Data from eligible studies were independently extracted by the 3 primary reviewers and verified for accuracy by the fourth reviewer. Discrepancies were resolved by discussion and consensus. We used data collection forms that included the following fields: title, author, year and country of publication, study design, sample size, patient demographic characteristics, Injury Severity Score, GCS score, definition of obtunded, mechanism of injury, CT specifications, further imaging or follow-up of patients with negative CT scans, image interpreter, missed acute cervical spine injuries, and changes in management. The 3 primary reviewers performed quality assessment independently. We used the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies-2) tool (24) and examined patient selection, the index test and reference standard used, and flow and timing to determine whether the risk of bias and concerns about applicability to the review question were low, unclear, or high among eligible studies. Definition of Variables Our primary outcome of interest was clinically significant cervical spine injury missed by CT and detected by the confirmatory test. A clinically significant injury was defined as one resulting in mechanical instability or requiring intervention or change in management. We excluded soft tissue signal changes that did not affect spine stability. The definition of cervical spine instability varied among included studies and was assessed by using many classification systems. Most eligible studies defined instability in accordance with the work of White and Panjabi (25) on biomechanics of the spine. Previous studies defined unstable and purely ligamentous injuries as those involving all 3 columns (26). We adopted and documented cervical spine instability outcomes as reported by the authors of included studies, regardless of the classification used. Changes in management after negative CT results and positive findings on a validating test included prolonged external immobilization or operative stabilization. An obtunded patient was defined as someone who was not fully awake and had an altered level of consciousness (GCS 14). These patients lacked a reliable neurologic examination that could aid in the diagnosis of spinal injury. High-quality CT scans were defined as those protocolled with narrow slice width (1 to 3 mm) and reconstruction in multiple planes. A well-interpreted CT study was defined as an image read by a health professional with special training and expertise in reading such images (that is, a consultant radiologist) rather than an on-call physician or radiology resident. Data Synthesis and Analysis Studies were grouped on the basis of how further evaluation of obtunded trauma patients with negative results from cervical spine CT was handled. The first group included studies that routinely performed MRI after a CT scan that was interpreted as normal. The second group comprised studies in which patients were routinely evaluated with dynamic radiography after negative CT results. The third group included studies in which patients were followed with serial physical examination after a normal CT result, with further imaging obtained as guided by clinical indications (for example, neurologic deficit). For each group, we examined mechanical cervical spine instability, need for operative stabilization, and collar use after negative CT results and additional findings on the confirmatory test. We examined high-quality studies separately. These reports fulfilled 4 criteria: prospective study design, low risk of bias and low concerns about applicability in all domains on the QUADAS-2 tool, well-interpreted CT images, and use of high-quality CT specifications. Given the small number of events (if any), formal meta-analysis was not possible. Data from individual studies are displayed in forest plots with 95% CIs. Exact binominal 1-sided 95% CIs were calculated for each proportion obtained from eligible studies (27). We used R, version 3.1.2 (R Foundation for Statistical Computing), to generate all forest plots. Role of the Funding Source This study received no funding. Results Characteristics of Included Studies Our search yielded 2112 results, of which 1959 were excluded after title and abstract screening. Another 125 were excluded after full-text review (Appendix Figure). The remaining 28 studies (2855) were included, and they reported on a total of 3627 obtunded blunt trauma patients with negative results from cervical spine CT and a validating test. Twenty studies (28, 29, 32, 34, 35, 37, 4044, 46, 4855) were retrospective cohort studies, and 8 (30, 31, 33, 36, 38, 39, 45, 47) were prospective cohort studies. Descriptions of eligible studies are provided in Appendix Tables 1 and 2. Details of methodological assessment of included studies with the QUADAS-2 tool are presented in Appendix Table 3. Appendix Figure. Summary of evidence search and selection. CT = computed tomography. Appendix Table 1. Characteristics of Included Studies Appendix Table 2. Outcomes of Eligible Studies Appendix Table 3. Quality Assessment of Eligible Studies Wit

Atraumatic versus conventional lumbar puncture needles: a systematic review and meta-analysis

OBJECT Although intracranial arachnoid cysts are a common incidental finding on pediatric brain imaging, only a subset of patients require surgery for them. For the minority who undergo surgery, the comparative effectiveness of various surgical approaches is debated. The authors explored predictors of surgery and compared operative techniques for pediatric patients with an intracranial arachnoid cyst seen at a tertiary care center. METHODS The authors reviewed records of pediatric patients with an intracranial arachnoid cyst. For each patient, data on baseline characteristics, the method of intervention, and surgical outcomes for the initial surgery were extracted, and cyst size at diagnosis was calculated (anteroposterior × craniocaudal × mediolateral). Baseline variables were analyzed as predictors of surgery by using logistic regression modeling, excluding patients whose surgery was not related to cyst size (i.e., those with obstructive hydrocephalus secondary to the cyst compressing a narrow CSF flow pathway or cyst rupture/hemorrhage). Data collected regarding surgical outcomes were analyzed descriptively. RESULTS Among 83 pediatric patients with an intracranial arachnoid cyst seen over a 25-year period (1989-2013), 27 (33%) underwent surgery; all had at least 1 cyst-attributed symptom/finding. In the multivariate model, age at presentation and cyst size at diagnosis were independent predictors of surgery. Cyst size had greater predictive value; specifically, the area under the curve for the receiver-operating-characteristic curve was 0.89 (95% CI 0.82-0.97), with an ideal cutoff point of ≥ 68 cm(3). This cutoff point had 100% sensitivity (95% CI 79%-100%), 75% specificity (95% CI 61%-85%), a 53% positive predictive value (95% CI 36%-70%), and a 100% negative predictive value (95% CI 91%-100%); the positive likelihood ratio was 4.0 (95% CI 2.5-6.3), and the negative likelihood ratio was 0 (95% CI 0-0.3). Although the multivariate model excluded 7 patients who underwent surgery (based on prespecified criteria), excluding these 7 cases did not change the overall findings, as shown in a sensitivity analysis that included all the cases. Descriptive results regarding surgical outcomes did not indicate any salient differences among the surgical techniques (endoscopic fenestration, cystoperitoneal shunting, or craniotomy-based procedures) in terms of symptom resolution within 6 months, need for reoperation to date, cyst-size change from before the operation, morbidity, or mortality. CONCLUSIONS The results of these exploratory analyses suggest that pediatric patients with an intracranial arachnoid cyst are more likely to undergo surgery if the cyst is large, compresses a narrow CSF flow pathway to cause hydrocephalus, or has ruptured/hemorrhaged. There were no salient differences among the 3 surgical techniques for several clinically important outcomes. A prospective multicenter study is required to enable more robust analyses, which could ultimately provide a decision-making framework for surgical indications and clarify any differences in the comparative effectiveness of surgical approaches to treating pediatric intracranial arachnoid cysts.

The identification of human pituitary adenoma-initiating cells

BACKGROUND Atraumatic needles have been proposed to lower complication rates after lumbar puncture. However, several surveys indicate that clinical adoption of these needles remains poor. We did a systematic review and meta-analysis to compare patient outcomes after lumbar puncture with atraumatic needles and conventional needles. METHODS In this systematic review and meta-analysis, we independently searched 13 databases with no language restrictions from inception to Aug 15, 2017, for randomised controlled trials comparing the use of atraumatic needles and conventional needles for any lumbar puncture indication. Randomised trials comparing atraumatic and conventional needles in which no dural puncture was done (epidural injections) or without a conventional needle control group were excluded. We screened studies and extracted data from published reports independently. The primary outcome of postdural-puncture headache incidence and additional safety and efficacy outcomes were assessed by random-effects and fixed-effects meta-analysis. This study is registered with the International Prospective Register of Systematic Reviews, number CRD42016047546. FINDINGS We identified 20 241 reports; after exclusions, 110 trials done between 1989 and 2017 from 29 countries, including a total of 31 412 participants, were eligible for analysis. The incidence of postdural-puncture headache was significantly reduced from 11·0% (95% CI 9·1-13·3) in the conventional needle group to 4·2% (3·3-5·2) in the atraumatic group (relative risk 0·40, 95% CI 0·34-0·47, p<0·0001; I2=45·4%). Atraumatic needles were also associated with significant reductions in the need for intravenous fluid or controlled analgesia (0·44, 95% CI 0·29-0·64; p<0·0001), need for epidural blood patch (0·50, 0·33-0·75; p=0·001), any headache (0·50, 0·43-0·57; p<0·0001), mild headache (0·52, 0·38-0·70; p<0·0001), severe headache (0·41, 0·28-0·59; p<0·0001), nerve root irritation (0·71, 0·54-0·92; p=0·011), and hearing disturbance (0·25, 0·11-0·60; p=0·002). Success of lumbar puncture on first attempt, failure rate, mean number of attempts, and the incidence of traumatic tap and backache did not differ significantly between the two needle groups. Prespecified subgroup analyses of postdural-puncture headache revealed no interactions between needle type and patient age, sex, use of prophylactic intravenous fluid, needle gauge, patient position, indication for lumbar puncture, bed rest after puncture, or clinician specialty. These results were rated high-quality evidence as examined using the grading of recommendations assessment, development, and evaluation. INTERPRETATION Among patients who had lumbar puncture, atraumatic needles were associated with a decrease in the incidence of postdural-puncture headache and in the need for patients to return to hospital for additional therapy, and had similar efficacy to conventional needles. These findings offer clinicians and stakeholders a comprehensive assessment and high-quality evidence for the safety and efficacy of atraumatic needles as a superior option for patients who require lumbar puncture. FUNDING None.