Meinhard Kieser

Efficacy of stapler versus hand-sewn closure after distal pancreatectomy (DISPACT): a randomised, controlled multicentre trial

BACKGROUND The ideal closure technique of the pancreas after distal pancreatectomy is unknown. We postulated that standardised closure with a stapler device would prevent pancreatic fistula more effectively than would a hand-sewn closure of the remnant. METHODS This multicentre, randomised, controlled, parallel group-sequential superiority trial was done in 21 European hospitals. Patients with diseases of the pancreatic body and tail undergoing distal pancreatectomy were eligible and were randomly assigned by central randomisation before operation to either stapler or hand-sewn closure of the pancreatic remnant. Surgical performance was assessed with intraoperative photo documentation. The primary endpoint was the combination of pancreatic fistula and death until postoperative day 7. Patients and outcome assessors were masked to group assignment. Interim and final analysis were by intention to treat in all patients in whom a left resection was done. This trial is registered, ISRCTN18452029. FINDINGS Between Nov 16, 2006, and July 3, 2009, 450 patients were randomly assigned to treatment groups (221 stapler; 229 hand-sewn closure), of whom 352 patients (177 stapler, 175 hand-sewn closure) were analysed. Pancreatic fistula rate or mortality did not differ between stapler (56 [32%] of 177) and hand-sewn closure (49 [28%] of 175; OR 0·84, 95% CI 0·53–1·33; p=0·56). One patient died within the fi rst 7 days after surgery in the hand-sewn group; no deaths occurred in the stapler group. Serious adverse events did not differ between groups. INTERPRETATION Stapler closure did not reduce the rate of pancreatic fistula compared with hand-sewn closure for distal pancreatectomy. New strategies, including innovative surgical techniques, need to be identified to reduce this adverse outcome. FUNDING German Federal Ministry of Education and Research.

Combining different phases in the development of medical treatments within a single trial

In the development of medical treatments, identification of promising therapies and inference on selected treatments are usually performed in subsequent separate trials. An adaptive two-stage design is proposed for the situation of multiple treatments to be compared with a control, allowing integration of both steps within a single confirmatory trial controlling the multiple level alpha. After the interim analysis, the trial may be terminated early or is continued with a second stage, where the set of treatments may be reduced due to lack of efficacy or to safety problems. The procedure is highly flexible with respect to the distributional assumptions, stopping rules and selection criteria and allows a completely free recalculation of the sample size for the second stage. Simulations show that the method may be substantially more powerful than classical one-stage multiple treatment designs with the same total sample size. As in conventional strategies with a series of separate experiments, a reasonable selection strategy has to be applied in order to prevent proceeding with non-optimal treatments.

Interrupted or continuous slowly absorbable sutures for closure of primary elective midline abdominal incisions: a multicenter randomized trial (INSECT: ISRCTN24023541).

Objective:In patients undergoing midline incisions, the abdominal fascia can be closed with a continuous or interrupted suture using various materials. The aim of this study is to compare: (1) interrupted technique with rapidly absorbable sutures and (2) continuous techniques with different slowly absorbable sutures, focusing on the incidence of incisional hernias within 1 year. Summary of Background Data:A meta-analysis suggested that the incidence of incisional hernias can be more effectively reduced with slowly absorbable continuous sutures. Methods:Multicenter randomized surgical trial with 3 parallel groups. Patients were scheduled for primary elective midline incisions. All surgeons were trained (4:1 suture wound length in continuous groups) and monitored. Primary end point, measured within 1 year after surgery, was the frequency of incisional hernias diagnosed by clinical examination and confirmed by ultrasound. Complications and safety were used as secondary end points. This study has been registered with the ISRCTN Register (INSECT: ISRCTN24023541). Results:Conducted on 625 randomized patients (210 interrupted Vicryl, 205 continuous polydioxanone suture (PDS), 210 continuous Monoplus), the primary analysis showed an incidence of 28 incisional hernias (15.9%) versus 15 (8.4%) versus 22 (12.5%) for the 3 closure techniques, respectively (P = 0.09). No significant difference was observed between the 3 groups with regard to burst abdomen (4 [2.0%] vs. 6 [3.0%] vs. 8 [4.0%], P = 0.46), wound infection (26 [12.7%] vs. 39 [19.4%] vs. 33 [16.3%], P = 0.19), pulmonary infections (9 [4.4%] vs. 5 [2.5%] vs. 5 [2.5%], P = 0.46), serious adverse events (63 [30.0%] vs. 57 [27.8%] vs. 61 [29.1%], P = 0.89), and 1-year mortality (16 [7.9%] vs. 11 [5.5%] vs. 16 [7.9%], P = 0.54). Conclusions:The incidence of incisional hernias and the frequency of wound infection was higher than expected in all groups. New concepts need to be developed and studied to substantially reduce the frequency of incisional hernias.

Inference on multiple endpoints in clinical trials with adaptive interim analyses

Planned interim analyses which permit early stopping or sample size adaption of a trial are desirable for ethical and scientific reasons. Multiple test procedures allow inference about several hypotheses within a single clinical trial. In this paper, a method which combines multiple testing with adaptive interim analyses whilst controlling the experimentwise error rate is proposed. The general closed testing principle, the situation of a priori ordered hypotheses, and application of the Bonferroni-Holm method are considered. The practical application of the method is demonstrated by an example.

Re-calculating the sample size in internal pilot study designs with control of the type I error rate.

When designing a clinical trial, there is usually some uncertainty about the variability of the primary outcome variable. This may lead to an unnecessarily high or inadequately low sample size. The internal pilot study approach uses data from patients recruited up to an interim stage to re-estimate the variance and to re-calculate the final sample size accordingly. Previously, simulation studies have shown that this methodology may highly improve the chance to obtain a well-powered trial. However, it also turned out that the type I error rate may be inflated by this procedure. We quantify the maximum excess of the type I error rate for normally distributed outcomes. If strict control of the alpha-level is considered to be an important issue, a method is proposed to achieve this when re-calculating the sample size in internal pilot studies. The characteristics of the power distributions are investigated for various sample size adaptation rules and implications are discussed.

Effect of Conscious Sedation vs General Anesthesia on Early Neurological Improvement Among Patients With Ischemic Stroke Undergoing Endovascular Thrombectomy: A Randomized Clinical Trial

Importance Optimal management of sedation and airway during thrombectomy for acute ischemic stroke is controversial due to lack of evidence from randomized trials. Objective To assess whether conscious sedation is superior to general anesthesia for early neurological improvement among patients receiving stroke thrombectomy. Design, Setting, and Participants SIESTA (Sedation vs Intubation for Endovascular Stroke Treatment), a single-center, randomized, parallel-group, open-label treatment trial with blinded outcome evaluation conducted at Heidelberg University Hospital in Germany (April 2014-February 2016) included 150 patients with acute ischemic stroke in the anterior circulation, higher National Institutes of Health Stroke Scale (NIHSS) score (>10), and isolated/combined occlusion at any level of the internal carotid or middle cerebral artery. Intervention Patients were randomly assigned to an intubated general anesthesia group (n = 73) or a nonintubated conscious sedation group (n = 77) during stroke thrombectomy. Main Outcomes and Measures Primary outcome was early neurological improvement on the NIHSS after 24 hours (0-42 [none to most severe neurological deficits; a 4-point difference considered clinically relevant]). Secondary outcomes were functional outcome by modified Rankin Scale (mRS) after 3 months (0-6 [symptom free to dead]), mortality, and peri-interventional parameters of feasibility and safety. Results Among 150 patients (60 women [40%]; mean age, 71.5 years; median NIHSS score, 17), primary outcome was not significantly different between the general anesthesia group (mean NIHSS score, 16.8 at admission vs 13.6 after 24 hours; difference, -3.2 points [95% CI, -5.6 to -0.8]) vs the conscious sedation group (mean NIHSS score, 17.2 at admission vs 13.6 after 24 hour; difference, -3.6 points [95% CI, -5.5 to -1.7]); mean difference between groups, -0.4 (95% CI, -3.4 to 2.7; P = .82). Of 47 prespecified secondary outcomes analyzed, 41 showed no significant differences. In the general anesthesia vs the conscious sedation group, substantial patient movement was less frequent (0% vs 9.1%; difference, 9.1%; P = .008), but postinterventional complications were more frequent for hypothermia (32.9% vs 9.1%; P < .001), delayed extubation (49.3% vs 6.5%; P < .001), and pneumonia (13.7% vs 3.9%; P = .03). More patients were functionally independent (unadjusted mRS score, 0 to 2 after 3 months [37.0% in the general anesthesia group vs 18.2% in the conscious sedation group P = .01]). There were no differences in mortality at 3 months (24.7% in both groups). Conclusions and Relevance Among patients with acute ischemic stroke in the anterior circulation undergoing thrombectomy, conscious sedation vs general anesthesia did not result in greater improvement in neurological status at 24 hours. The study findings do not support an advantage for the use of conscious sedation. Trial Registration clinicaltrials.gov Identifier: NCT02126085.

Cryoballoon Versus Open Irrigated Radiofrequency Ablation in Patients With Paroxysmal Atrial Fibrillation: The Prospective, Randomized, Controlled, Noninferiority FreezeAF Study

Background— There is a lack of data on the comparative efficacy and procedural safety of open irrigated radiofrequency (RF) and cryoballoon catheter (CB) ablation for pulmonary vein isolation in patients with paroxysmal atrial fibrillation. Methods and Results— In a prospective, noninferiority study, 315 patients were randomly assigned to RF (n=159) or CB (n=156) ablation. The primary end point was freedom from atrial arrhythmia with absence of persistent complications. Patients were largely comparable between groups with more vascular disease in the RF group (8.2% versus 2.6% for CB; P=0.028). The primary end point at 12 months was achieved by 70.7% with RF and 73.6% with CB (multiple procedure success), including 31 redo procedures in each group (19.5% of RF versus 19.9% of CB; P=0.933). For the intention-to-treat population, noninferiority of CB was revealed for the predefined inferiority margin (risk difference, 0.029; 95% confidence interval, −0.074 to 0.132; P<0.001). Rates at 6 months were 63.1% and 64.1% for the RF and CB groups (single procedure success), and noninferiority was confirmed (risk difference, 0.010; 95% confidence interval, −0.097 to 0.116; P=0.002). Periprocedural complications for the index procedure were more frequent in the CB group (5.0% RF, 12.2% CB; P=0.022) with a significant difference in phrenic nerve palsies (0% RF, 5.8% CB; P=0.002). Conclusion— This large, prospective, randomized, controlled study demonstrates noninferiority of CB ablation versus RF ablation for treating patients with paroxysmal atrial fibrillation. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00774566.

Preoperative chemo(radio)therapy versus primary surgery for gastroesophageal adenocarcinoma: Systematic review with meta-analysis combining individual patient and aggregate data

BACKGROUND The prognosis of patients with gastroesophageal adenocarcinoma is poor. There is conflicting evidence regarding effects of preoperative chemotherapy on survival and other outcomes. METHODS We conducted a meta-analysis with aggregate and individual patient data (IPD) to assess the effect of preoperative chemotherapy for gastroesophageal adenocarcinoma on survival and other outcomes. Two independent reviewers identified eligible randomised controlled trials (RCTs) comparing chemotherapy+/-radiotherapy followed by surgery with surgery alone for gastroesophageal adenocarcinoma. IPD was solicited from all trials. Meta-analyses were performed using the two stage method. RESULTS We identified 14 RCTs (2422 patients). For eight RCTs (1049 patients; 43.3%) we obtained IPD. Preoperative chemotherapy was associated with longer overall survival (hazard ratio [HR] 0.81; 95% confidence interval [CI] 0.73-0.89; p<0.0001). There were larger treatment effects in tumours of the gastroesophageal junction and for chemoradiotherapy compared to chemotherapy, but the tests for subgroup differences were not statistically significant. Preoperative chemotherapy was associated with longer disease-free survival, higher likelihood of R0 resection and more favourable post-treatment tumour stage, but not perioperative complications. CONCLUSION Preoperative chemotherapy for locoregional gastroesophageal adenocarcinoma increases survival compared to surgery alone. It should be offered to all eligible patients. There appear to be larger survival advantages in tumours of the gastroesophageal junction and for chemoradiotherapy, but these findings require prospective confirmation.

Resection of the primary tumour versus no resection prior to systemic therapy in patients with colon cancer and synchronous unresectable metastases (UICC stage IV): SYNCHRONOUS - a randomised controlled multicentre trial (ISRCTN30964555)

BackgroundCurrently, it remains unclear, if patients with colon cancer and synchronous unresectable metastases who present without severe symptoms should undergo resection of the primary tumour prior to systemic chemotherapy. Resection of the primary tumour may be associated with significant morbidity and delays the beginning of chemotherapy. However, it may prevent local symptoms and may, moreover, prolong survival as has been demonstrated in patients with metastatic renal cell carcinoma. It is the aim of the present randomised controlled trial to evaluate the efficacy of primary tumour resection prior to systemic chemotherapy to prolong survival in patients with newly diagnosed colon cancer who are not amenable to curative therapy.Methods/designThe SYNCHRONOUS trial is a multicentre, randomised, controlled, superiority trial with a two-group parallel design. Colon cancer patients with synchronous unresectable metastases are eligible for inclusion. Exclusion criteria are primary tumour-related symptoms, inability to tolerate surgery and/or systemic chemotherapy and history of another primary cancer. Resection of the primary tumour as well as systemic chemotherapy is provided according to the standards of the participating institution. The primary endpoint is overall survival that is assessed with a minimum follow-up of 36 months. Furthermore, it is the objective of the trial to assess the safety of both treatment strategies as well as quality of life.DiscussionThe SYNCHRONOUS trial is a multicentre, randomised, controlled trial to assess the efficacy and safety of primary tumour resection before beginning of systemic chemotherapy in patients with metastatic colon cancer not amenable to curative therapy.Trial registrationISRCTN30964555

Sample size determination for proving equivalence based on the ratio of two means for normally distributed data

Equivalence trials aim to demonstrate that two treatments do not differ by more than a prespecified clinically irrelevant amount. We consider the problem when equivalence is defined in terms of the ratio of population means and the original (untransformed) data are normally distributed. Application of the intersection-union principle to the test proposed by Sasabuchi results in a two one-sided tests procedure of size alpha. We give the associated 100 (1-2 alpha) per cent confidence interval and derive the exact methods for calculation of power and sample sizes for the parallel group design and the two-period cross-over. We present tables and figures of required sample sizes and achieved power.