Michel W.J.M. Wouters

Systematic review and meta‐analysis of the volume–outcome relationship in pancreatic surgery

Many studies have shown lower mortality and higher survival rates after pancreatic surgery with high‐volume providers, suggesting that centralization of pancreatic surgery can improve outcomes. The methodological quality of these studies is open to question. This study involves a systematic review of the volume–outcome relationship for pancreatic surgery with a meta‐analysis of studies considered to be of good quality.

The volume-outcome relation in the surgical treatment of esophageal cancer: a systematic review and meta-analysis.

This study was undertaken to conduct a systematic review and meta‐analysis of the literature on the relation between procedural volume and outcome of esophagectomies. A systematic search was carried out to identify articles investigating effects of hospital or surgeon volume on short‐term and long‐term outcomes published between 1995 and 2010. Articles were scrutinized for methodological quality, and after inclusion of only high‐quality studies, a meta‐analysis assuming a random effects model was done to estimate the effect of higher volume on patient outcome. Heterogeneity in study results was evaluated with an I2‐test and risk of publication bias with an Egger regression intercept. Forty‐three studies were found. Sixteen studies met the strict inclusion criteria for the meta‐analysis on hospital volume and postoperative mortality and 4 studies on hospital volume and survival. The pooled estimated effect size was significant for high‐volume providers in the analysis of postoperative mortality (odds ratio [OR], 2.30; 95% confidence interval [CI], 1.89‐2.80) and in the survival analysis (OR, 1.17; 95% CI, 1.05‐1.30). The meta‐analysis of surgical volume and outcome showed no significant results. Studies in which the results were adjusted not only for patient characteristics but also for tumor characteristics and urgency of the operation showed a stronger correlation between hospital volume and mortality. Also, studies performed on data from the United States showed higher effect sizes. The evidence for hospital volume as an important determinant of outcome in esophageal cancer surgery is strong. Concentration of procedures in high‐volume hospitals with a dedicated setting for the treatment of esophageal cancer might lead to an overall improvement in patient outcome. Cancer 2012;.

A systematic review and meta-analysis of the relationship between hospital/surgeon volume and outcome for radical cystectomy: an update for the ongoing debate.

CONTEXT There is an ongoing debate about centralisation of radical cystectomy (RC) procedures. OBJECTIVE To conduct a systematic review of the literature on the volume-outcome relationship for RC for bladder cancer (BCa) with consideration for the methodologic quality of the available evidence and to perform a meta-analysis on the studies meeting predefined quality criteria. EVIDENCE ACQUISITION A systematic search was performed to identify all articles examining the effects of procedure volume on clinical outcome for cystectomy. Reviews, opinion articles, and surveys were excluded. All articles were critically appraised for methodologic quality and risk of bias. Meta-analysis was performed to calculate the overall effect of higher surgeon or hospital volume on patient outcome. EVIDENCE SYNTHESIS Ten studies of good methodologic quality were included for meta-analysis. Eight studies were based on administrative data, two studies on clinical data. The results showed a significant association between high-volume hospitals and low mortality. A meta-analysis of the seven studies on hospital mortality showed a pooled estimated effect of odds ratio (OR) 0.55 (range: 0.44-0.69). The result was moderate heterogeneity (I(2)=50). A large variation in cut-off points used was observed. Sensitivity analyses did not show different effects in any of the subgroup analyses. Also, no significant differences in effect sizes were observed for different cut-off points. The data were not suggestive for publication bias. One study showed a positive effect of hospital volume on survival (hazard ratio [HR]: 0.89; p=0.06). Two studies showed a beneficial effect of surgeon volume on mortality (OR: 0.55; OR: 0.64). Only one study on the impact of surgeon volume on survival was found; it showed no significant positive effect for higher volume (HR: 0.83; p=0.26). CONCLUSIONS Postoperative mortality after cystectomy is significantly inversely associated with high-volume providers. However, additional quality criteria, such as infrastructure and level of specialisation, should be formulated to direct centralisation initiatives. The Dutch Association of Urology in 2010 implemented a national quality of care (QoC) registration programme for all patients treated by surgery for muscle-invasive BCa, including multiple parameters defining QoC.

Differences in outcomes of oesophageal and gastric cancer surgery across Europe

In several European countries, centralization of oesophagogastric cancer surgery has been realized and clinical audits initiated. The present study was designed to evaluate differences in resection rates, outcomes and annual hospital volumes between these countries, and to analyse the relationship between hospital volume and outcomes.

Increased incidence and survival for oesophageal cancer but not for gastric cardia cancer in the Netherlands

INTRODUCTION A worldwide increasing incidence is seen for oesophageal adenocarcinoma, but not for oesophageal squamous cell carcinoma (SCC) and gastric cardia adenocarcinoma. Purposes of the current study were to evaluate the changing incidence rates of oesophageal and gastric cardia cancer, and to assess survival trends. PATIENTS AND METHODS Patients diagnosed with oesophageal adenocarcinoma (N=12,195) or SCC (N=9046), or gastric cardia adenocarcinoma (N=9900) between 1989 and 2008 in the Netherlands were included. Changes in European Standard Population (ESP) and relative survival over time were evaluated. RESULTS Incidence rates for oesophageal adenocarcinoma increased in males (+7.5%, P<0.001) and females (+5.2%, P<0.001), while the incidence for oesophageal SCC remained stable in males (-0.2%, P=0.6) and slightly increased in females (+1.7%, P=0.001). The incidence for gastric cardia cancer decreased in males (-1.2%, P<0.006), and remained stable in females (-0.2%, P=0.7). Five-year survival for both M0 and M1 oesophageal carcinoma doubled over the last 20 years. No significant changes in survival were found for M0 and M1 gastric cardia carcinoma. DISCUSSION In the Netherlands, a rising incidence is seen for oesophageal adenocarcinoma, but not for gastric cardia adenocarcinoma. This finding most likely reflects true changes in disease burden, rather than being the result of changes in diagnosis or classification. The increased survival for oesophageal carcinoma can be attributed to centralisation of surgery, and an increased use of multimodality therapy, factors hardly acknowledged for gastric cancer.

Effect of hospital volume on postoperative mortality and survival after oesophageal and gastric cancer surgery in the Netherlands between 1989 and 2009.

BACKGROUND High hospital volume is associated with better outcomes after oesophagectomy and gastrectomy. In the Netherlands, a minimal volume standard of 10 oesophagectomies per year was introduced in 2006. For gastrectomy, no minimal volume standard was set. Aims of this study were to describe changes in hospital volumes, mortality and survival and to explore if high hospital volume is associated with better outcomes after oesophagectomy and gastrectomy in the Netherlands. METHODS From 1989 to 2009, 24,246 patients underwent oesophagectomy (N = 10,025) or gastrectomy (N = 14,221) in the Netherlands. Annual hospital volumes were defined as very low (1-5), low (6-10), medium (11-20), and high (≥ 21). Volume-outcome analyses were performed using Cox regression, adjusting for year of diagnosis, case-mix and the use of multi-modality treatment. RESULTS From 1989 to 2009, the percentage of patients treated in high-volume hospitals increased for oesophagectomy (from 7% to 64%), but decreased for gastrectomy (from 8% to 5%). Six-month mortality (from 15% to 7%) and 3-year survival (from 41% to 52%) improved after oesophagectomy, and to a lesser extent after gastrectomy (6-month mortality: 15%-10%, three-year survival: 55-58%). High hospital volume was associated with lower 6-month mortality (hazard ratio (HR) 0.48, P<0.001) and longer 3-year survival (HR 0.77, P<0.001) after oesophagectomy, but not after gastrectomy. CONCLUSIONS Oesophagectomy was effectively centralised in the Netherlands, improving mortality and survival. Gastrectomies were mainly performed in low volumes, and outcomes after gastrectomy improved to a lesser extent, indicating an urgent need for improvement in quality of surgery and perioperative care for gastric cancer in the Netherlands.

Impact of centralization of pancreatic cancer surgery on resection rates and survival

Centralization of pancreatic surgery has been shown to reduce postoperative mortality. It is unknown whether resection rates and survival have also improved. The aim of this study was to analyse the impact of nationwide centralization of pancreatic surgery on resection rates and long‐term survival.

A systematic review and meta-analysis of the volume-outcome relationship in the surgical treatment of breast cancer. Are breast cancer patients better of with a high volume provider?

AIMS To conduct a systematic review of the literature on the volume-outcome relationship for the surgical treatment of breast cancer with consideration of the methodological quality of the available evidence and to perform a meta-analysis on the studies of considered good quality. METHODS A systematic search was done to identify all articles examining the effects of hospital or surgeon volume on clinical outcome of the surgical treatment of breast cancer. Reviews, opinion articles and surveys were excluded. All articles were critically appraised on methodological quality and risk of bias. After strict inclusion, meta-analysis assuming a random effects model was done to estimate the effect of higher hospital or surgeon volume on patient outcome. RESULTS We found 12 studies of good methodological quality which could be included for meta-analysis. The results showed a significant association between high volume providers and an improved survival. The association is the most robust for surgeon volume (HR 0.80 (0.71-0.90) and RR 0.85 (0.80-0.90). In addition there is an effect of hospital volume on the in-hospital mortality, although the mortality was very low (0.1-0.2%). Results of meta-analysis were heterogeneous. Sensitivity analysis showed a larger effect size for studies also adjusting for comorbidity for both studies on hospital and surgeon volume. The data were not suggestive for publication bias. CONCLUSIONS The results show that survival after breast cancer surgery is significantly associated with high volume providers.

The Relationship Between Volume or Surgeon Specialty and Outcome in the Surgical Treatment of Lung Cancer A Systematic Review and Meta-Analysis

Background: Whether improvement of quality of surgical cancer care can be achieved by centralizing care in high-volume specialized centers is a subject of ongoing debate. We have conducted a meta-analysis of the literature on the effect of procedural volume or surgeon specialty on outcome of lung resections for cancer. Methods: A systematic search of articles published between January 1, 1990 and January 20, 2011 on the effects of surgeon specialty and hospital or surgeon volume of lung resections on mortality and survival was conducted. After strict inclusion, meta-analysis assuming a random-effects model was performed. Meta-regression was used to identify volume cutoff values. Heterogeneity and the risk of publication bias were evaluated. Results: Nineteen relevant studies were found. Studies were heterogeneous, especially in defining volume categories. The pooled estimated effect size was significant in favor of high-volume hospitals regarding postoperative mortality (odds ratio [OR] 0.71; confidence interval 0.62–0.81), but not for survival (OR 0.93; confidence interval 0.84–1.03). Surgeon volume showed no significant effect on outcome. General surgeons had significantly higher mortality risks than general thoracic (OR 0.78; 0.70–0.88) or cardiothoracic surgeons (OR 0.82; 0.69–0.96). A minimal annual volume of resections for lung cancer could not be identified. Conclusions: Hospital volume and surgeon specialty are important determinants of outcome in lung cancer resections, but evidence-based minimal-volume standards are lacking. Evaluation of individual institutions in a national audit program might help elucidate the influence of individual quality-of-care parameters, including hospital volume, on outcome.

Successful and safe introduction of laparoscopic colorectal cancer surgery in Dutch hospitals

Objective:To investigate the safety of laparoscopic colorectal cancer resections in a nationwide population-based study. Background:Although laparoscopic techniques are increasingly used in colorectal cancer surgery, little is known on results outside trials. With the fast introduction of laparoscopic resection (LR), questions were raised about safety. Methods:Of all patients who underwent an elective colorectal cancer resection in 2010 in the Netherlands, 93% were included in the Dutch Surgical Colorectal Audit. Short-term outcome after LR, open resection (OR), and converted LR were compared in a generalized linear mixed model. We further explored hospital differences in LR and conversion rates. Results:A total of 7350 patients, treated in 90 hospitals, were included. LR rate was 41% with a conversion rate of 15%. After adjustment for differences in case-mix, LR was associated with a lower risk of mortality (odds ratio 0.63, P < 0.01), major morbidity (odds ratio 0.72, P < 0.01), any complications (odds ratio 0.74, P < 0.01), hospital stay more than 14 days (odds ratio 0.71, P < 0.01), and irradical resections (odds ratio 0.68, P < 0.01), compared to OR. Outcome after conversion was similar to OR (P > 0.05). A large variation in LR and conversion rates among hospitals was found; however, the difference in outcome associated with operative techniques was not influenced by hospital of treatment. Conclusions:Use of laparoscopic techniques in colorectal cancer surgery in the Netherlands is safe and results are better in short-term outcome than open surgery, irrespective of the hospital of treatment. Outcome after conversion was similar to OR.