Kevin Phan

Systematic review and meta-analysis: techniques and a guide for the academic surgeon

With the rapidly growing literature across the surgical disciplines, there is a corresponding need to critically appraise and summarize the currently available evidence so they can be applied appropriately to patient care. The interpretation of systematic reviews is particularly challenging in cases where few robust clinical trials have been performed to address a particular question. However, risk of bias can be minimized and potentially useful conclusions can be drawn if strict review methodology is adhered to, including an exhaustive literature search, quality appraisal of primary studies, appropriate statistical methodology, assessment of confidence in estimates and risk of bias. Therefore, the following article aims to: (I) summarize to the important features of a thorough and rigorous systematic review or meta-analysis for the surgical literature; (II) highlight several underused statistical approaches which may yield further interesting insights compared to conventional pair-wise data synthesis techniques; and (III) propose a guide for thorough analysis and presentation of results.

Sutureless aortic valve replacement: a systematic review and meta-analysis.

BACKGROUND Sutureless aortic valve replacement (SU-AVR) has emerged as an innovative alternative for treatment of aortic stenosis. By avoiding the placement of sutures, this approach aims to reduce cross-clamp and cardiopulmonary bypass (CPB) duration and thereby improve surgical outcomes and facilitate a minimally invasive approach suitable for higher risk patients. The present systematic review and meta-analysis aims to assess the safety and efficacy of SU-AVR approach in the current literature. METHODS Electronic searches were performed using six databases from their inception to January 2014. Relevant studies utilizing sutureless valves for aortic valve implantation were identified. Data were extracted and analyzed according to predefined clinical endpoints. RESULTS Twelve studies were identified for inclusion of qualitative and quantitative analyses, all of which were observational reports. The minimally invasive approach was used in 40.4% of included patients, while 22.8% underwent concomitant coronary bypass surgery. Pooled cross-clamp and CPB duration for isolated AVR was 56.7 and 46.5 minutes, respectively. Pooled 30-day and 1-year mortality rates were 2.1% and 4.9%, respectively, while the incidences of strokes (1.5%), valve degenerations (0.4%) and paravalvular leaks (PVL) (3.0%) were acceptable. CONCLUSIONS The evaluation of current observational evidence suggests that sutureless aortic valve implantation is a safe procedure associated with shorter cross-clamp and CPB duration, and comparable complication rates to the conventional approach in the short-term.

Lumbar interbody fusion: techniques, indications and comparison of interbody fusion options including PLIF, TLIF, MI-TLIF, OLIF/ATP, LLIF and ALIF.

Degenerative disc and facet joint disease of the lumbar spine is common in the ageing population, and is one of the most frequent causes of disability. Lumbar spondylosis may result in mechanical back pain, radicular and claudicant symptoms, reduced mobility and poor quality of life. Surgical interbody fusion of degenerative levels is an effective treatment option to stabilize the painful motion segment, and may provide indirect decompression of the neural elements, restore lordosis and correct deformity. The surgical options for interbody fusion of the lumbar spine include: posterior lumbar interbody fusion (PLIF), transforaminal lumbar interbody fusion (TLIF), minimally invasive transforaminal lumbar interbody fusion (MI-TLIF), oblique lumbar interbody fusion/anterior to psoas (OLIF/ATP), lateral lumbar interbody fusion (LLIF) and anterior lumbar interbody fusion (ALIF). The indications may include: discogenic/facetogenic low back pain, neurogenic claudication, radiculopathy due to foraminal stenosis, lumbar degenerative spinal deformity including symptomatic spondylolisthesis and degenerative scoliosis. In general, traditional posterior approaches are frequently used with acceptable fusion rates and low complication rates, however they are limited by thecal sac and nerve root retraction, along with iatrogenic injury to the paraspinal musculature and disruption of the posterior tension band. Minimally invasive (MIS) posterior approaches have evolved in an attempt to reduce approach related complications. Anterior approaches avoid the spinal canal, cauda equina and nerve roots, however have issues with approach related abdominal and vascular complications. In addition, lateral and OLIF techniques have potential risks to the lumbar plexus and psoas muscle. The present study aims firstly to comprehensively review the available literature and evidence for different lumbar interbody fusion (LIF) techniques. Secondly, we propose a set of recommendations and guidelines for the indications for interbody fusion options. Thirdly, this article provides a description of each approach, and illustrates the potential benefits and disadvantages of each technique with reference to indication and spine level performed.

Surgical left atrial appendage occlusion during cardiac surgery for patients with atrial fibrillation: a meta-analysis

OBJECTIVES Concomitant left atrial appendage occlusion (LAAO) during surgical ablation has emerged as a potential treatment strategy to reduce stroke and perioperative mortality in patients with atrial fibrillation (AF). The present meta-analysis aims to assess current evidence on the efficacy and safety between LAAO and LAA preservation cohorts for patients undergoing cardiac surgery. METHODS Electronic searches were performed using six electronic databases from their inception to November 2013, identifying all relevant comparative randomized and observational studies comparing LAAO with non-LAAO in AF patients undergoing cardiac surgery. Data were extracted and analysed according to predefined endpoints including mortality, stroke, postoperative AF and reoperation for bleeding. RESULTS Seven relevant studies identified for qualitative and quantitative analyses, including 3653 patients undergoing LAAO (n = 1716) versus non-LAAO (n = 1937). Stroke incidence was significantly reduced in the LAAO occlusion group at the 30-day follow-up [0.95 vs 1.9%; odds ratio (OR) 0.46; P = 0.005] and the latest follow-up (1.4 vs 4.1%; OR 0.48; P = 0.01), compared with the non-LAAO group. Incidence of all-cause mortality was significantly decreased with LAAO (1.9 vs 5%; OR 0.38; P = 0.0003), while postoperative AF and reoperation for bleeding was comparable. CONCLUSIONS While acknowledging the limitations and inadequate statistical power of the available evidence, this study suggests LAAO as a promising strategy for stroke reduction perioperatively and at the short-term follow-up without a significant increase in complications. Larger randomized studies in the future are required, with clearer surgical and anticoagulation protocols and adequate long-term follow-up, to validate the clinical efficacy of LAAO versus non-LAAO groups.

Surgical ablation for treatment of atrial fibrillation in cardiac surgery: a cumulative meta-analysis of randomised controlled trials

Introduction Concomitant surgical ablation is a treatment modality for patients with atrial fibrillation (AF) undergoing cardiac surgery, however, its efficacy and clinical outcomes are not well established. The present study is the first cumulative meta-analysis of randomised controlled trials (RCT) on clinical outcomes of surgical ablation versus no ablative treatment in all patients with cardiac surgery. Methods Electronic searches were performed using six databases from their inception to October 2013, identifying all relevant RCTs comparing surgical ablation versus no ablation in patients with AF undertaking cardiac surgery. Data were extracted and analysed according to predefined clinical endpoints. Results Sixteen relevant RCTs were identified for the present study. Higher prevalence of sinus rhythm in the surgical ablation group was evident at all ≥12 month follow-up (OR, 6.72; 95% CI 4.88 to 9.25; p<0.00001). There were no significant differences between surgical ablation versus no ablation in terms of mortality (OR, 1.05; 95% CI 0.66 to 1.68; p=0.83), pacemaker implantations (OR, 0.88; 95% CI 0.51 to 1.51; p=0.64), and neurological events (OR, 0.86; 95% CI 0.37 to 2.04; p=0.74). Cumulative meta-analysis demonstrated that these trends have remained consistent over the years, with recent studies narrowing the CIs of the summary estimates. Conclusions The evaluation of the current randomised trials demonstrates that concomitant surgical ablation and cardiac surgery is safe and effective at restoring sinus rhythm.

A systematic review and meta-analysis of clinical and patient-reported outcomes following two procedures for recurrent traumatic anterior instability of the shoulder: Latarjet procedure vs. Bankart repair

BACKGROUND The Bankart repair and Latarjet procedure are both viable surgical options for recurrent traumatic anterior instability of the shoulder joint. The anatomic repair is the more popular option, with 90% of surgeons internationally choosing the Bankart repair as the initial treatment. There has been no previous review directly comparing the 2 techniques. Hence, we aimed to systematically review studies to compare the outcomes of Bankart repairs vs. the Latarjet procedure for recurrent instability of the shoulder. METHODS Six electronic databases were searched for original, English-language studies comparing the Bankart and Latarjet procedures. Studies were critically appraised using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist. Data were extracted from the text, tables, and figures of the selected studies. RESULTS Eight comparative studies were identified with 795 shoulders; 416 of them underwent open or arthroscopic Bankart repairs, and 379 were repaired by the open Latarjet procedure. Primary and revision procedures were studied. The Latarjet procedure conferred significantly lower risk of recurrence and redislocation. There was no significant difference in the rates of complication requiring reoperation between the two procedures. Rowe scores were higher and loss of external rotation lower in the Latarjet group compared with the Bankart repair group. CONCLUSIONS Our studies demonstrate that the Latarjet procedure is a viable and possibly superior alternative to the Bankart repair, offering greater stability with no significant increase in complication rate. However, the studies identified were retrospective and of limited quality, and therefore randomized controlled trials with large populations of patients or prospective assessment of national orthopedic registries should be employed to confirm our findings.

Venoarterial Extracorporeal Membrane Oxygenation for Cardiogenic Shock and Cardiac Arrest: A Meta-Analysis

OBJECTIVE To evaluate the effect of extracorporeal membrane oxygenation (ECMO) on survival and complication rates in adults with refractory cardiogenic shock or cardiac arrest. DESIGN Meta-analysis. SETTING University hospitals. PARTICIPANTS One thousand one hundred ninety-nine patients from 22 observational studies. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Observational studies published from the year 2000 onwards, examining at least 10 adult patients who received ECMO for refractory cardiogenic shock or cardiac arrest were included. Pooled estimates with 95% confidence intervals were calculated based on the Freeman-Tukey double-arcsine transformation and DerSimonian-Laird random-effect model. Survival to discharge was 40.2% (95% confidence intervals [CI], 33.9-46.7), while survival at 3, 6, and 12 months was 55.9% (95% CI, 41.5-69.8), 47.6% (95% CI, 25.4-70.2), and 54.4% (95% CI, 36.6-71.7), respectively. Survival up to 30 days was higher in cardiogenic shock patients (52.5%, 95% CI, 43.7%-61.2%) compared to cardiac arrest (36.2%, 95% CI, 23.1%-50.4%). Concurrently, complication rates were particularly substantial for neurologic deficits (13.3%, 95% CI, 8.3-19.3), infection (25.1%, 95%CI, 15.9-35.5), and renal impairment (47.4%, 95% CI, 30.2-64.9). Significant heterogeneity was detected, although its levels were similar to previous meta-analyses that only examined short-term survival to discharge. CONCLUSIONS Venoarterial ECMO can improve short-term survival in adults with refractory cardiogenic shock or cardiac arrest. It also may provide favorable long-term survival at up to 3 years postdischarge. However, ECMO also is associated with significant complication rates, which must be incorporated into the risk-benefit analysis when considering treatment. These findings require confirmation by large, adequately controlled and standardized trials with long-term follow-up.

Anterior lumbar interbody fusion versus transforaminal lumbar interbody fusion – systematic review and meta-analysis

Purpose. To assess the clinical and radiographic outcomes and complications of anterior lumbar interbody fusion (ALIF) versus transforaminal lumbar interbody fusion (TLIF). Methods. A systematic literature search was conducted from six electronic databases. The relative risk and weighted mean difference (WMD) were used as statistical summary effect sizes. Results. Fusion rates (88.6% vs. 91.9%, P = 0.23) and clinical outcomes were comparable between ALIF and TLIF. ALIF was associated with restoration of disk height (WMD, 2.71 mm, P = 0.01), segmental lordosis (WMD, 2.35, P = 0.03), and whole lumbar lordosis (WMD, 6.33, P = 0.03). ALIF was also associated with longer hospitalization (WMD, 1.8 days, P = 0.01), lower dural injury (0.4% vs. 3.8%, P = 0.05) but higher blood vessel injury (2.6% vs. 0%, P = 0.04). Conclusions. ALIF and TLIF appear to have similar success and clinical outcomes, with different complication profiles. ALIF may be associated with superior restoration of disk height and lordosis, but requires further validation in future studies.

A meta-analysis of minimally invasive versus conventional mitral valve repair for patients with degenerative mitral disease

BACKGROUND Minimally invasive mitral valve surgery through a mini-thoracotomy approach was developed in the mid-1990s as an alternative to conventional sternotomy, but with reduced trauma and quicker recovery. However, technical demands and a paucity of comparative data have thus far limited the widespread adoption of minimally invasive mitral valve repair (MIMVR). Previous meta-analyses have grouped various surgical techniques and underlying valvular disease aetiologies together for comparison. The present study aimed to compare the clinical outcomes of MIMVR versus conventional mitral valve repair in patients with degenerative mitral valve disease. METHODS A systematic review of the current literature was performed through nine electronic databases from January 1995 to July 2013 to identify all relevant studies with comparative data on MIMVR versus conventional mitral valve surgery. Measured endpoints included mortality, stroke, renal failure, wound infection, reoperation for bleeding, aortic dissection, myocardial infarction, atrial fibrillation, readmission within 30 days, cross clamp time, cardiopulmonary bypass time and durations of intensive care unit (ICU) stay and overall hospitalization. Echocardiographic outcomes were also assessed when possible. RESULTS Seven relevant studies were identified according to the predefined study selection criteria, including one randomized controlled trial and six retrospective studies. Meta-analysis of clinical outcomes did not identify any statistically significant differences between MIMVR and conventional mitral valve repair. The duration of ICU stay was significantly shorter for patients who underwent MIMVR, but this did not translate to a shorter hospitalization period. Patients who underwent MIMVR required longer cross clamp time as well as cardiopulmonary bypass time. Both surgical techniques appeared to achieve satisfactory echocardiographic outcomes. Pain-related outcomes was assessed in one study and reported significantly less pain for patients who underwent MIMVR. However, this limited data was not suitable for meta-analysis. CONCLUSIONS The existing literature has limited data on comparative outcomes after MIMVR versus conventional mitral valve repair for patients with degenerative disease. From the available evidence, there are no significant differences between the two surgical techniques in regards to clinical outcomes. Patients who underwent MIMVR required longer cardiopulmonary bypass and cross clamp times, but the duration of stay in the ICU was significantly shorter than conventional mitral valve repair.

Systematic reviews and meta-analyses in spine surgery, neurosurgery and orthopedics: guidelines for the surgeon scientist

The research evidence in the realm of surgery is expanding at a rapid pace, and thus corresponds with an increasing need to critically appraise and synthesize the available literature. Particularly in fields such as spine surgery, neurosurgery and orthopedics which traditionally have little Class I randomized clinical data, reviews are important to pool the available evidence on clinical questions which are otherwise difficult to answer. Whilst systematic reviews and meta-analyses have the potential to provide critical and updated surgical evidence to guide clinical decisions, poorly performed analyses and misinterpretation of such reviews may have a detrimental effect on patient care and outcomes. We present a summary of the critical steps in performing a systematic review and meta-analysis, allowing the surgeon scientist to better interpret and perform their own systematic reviews and meta-analyses.