Toward Optimizing Risk Adjustment in the Dutch Surgical Aneurysm Audit

Background: To compare hospital outcomes of aortic aneurysm surgery, casemix correction for preoperative variables is essential. Most of these variables can be deduced from mortality risk prediction models. Our aim was to identify the optimal set of preoperative variables associated with mortality to establish a relevant and efficient casemix model.Methods: All patients prospectively registered between 2013 and 2016 in the Dutch Surgical Aneurysm Audit (DSAA) were included for the analysis. After multiple imputation for missing variables, predictors for mortality following univariable logistic regression were analyzed in a manual backward multivariable logistic regression model and compared with three standard mortality risk prediction models: Glasgow Aneurysm Score (GAS, mainly clinical parameters), Vascular Biochemical and Haematological Outcome Model (VBHOM, mainly laboratory parameters), and Dutch Aneurysm Score (DAS, both clinical and laboratory parameters). Discrimination and calibration were tested and considered good with a C-statistic &gt; 0.8 and Hosmer-Lemeshow (H-L) P &gt; 0.05. Results: There were 12,401 patients: 9,537 (76.9%) elective patients (EAAA), 913 (7.4%) acute symptomatic patients (SAAA), and 1,951 (15.7%) patients with acute rupture (RAAA). Overall postoperative mortality was 6.5%; 1.8% after EAAA surgery, 6.6% after SAAA, and 29.6% after RAAA surgery. The optimal set of independent variables associated with mortality was a mix of clinical and laboratory parameters: gender, age, pulmonary comorbidity, operative setting, creatinine, aneurysm size, hemoglobin, Glasgow coma scale, electrocardiography, and systolic blood pressure (C-statistic 0.871). External validation overall of VBHOM, DAS, and GAS revealed C-statistics of 0.836, 0.782, and 0.761, with an H-L of 0.028, 0.00, and 0.128, respectively.Conclusions: The optimal set of variables for casemix correction in the DSAA comprises both clinical and laboratory parameters, which can be collected easily from electronic patient files and will lead to an efficient casemix model.</p

Obesity as a determinant of perioperative and postoperative outcome in patients following colorectal cancer surgery: A population-based study (2009–2016)

Background: Obesity is an increasing problem worldwide that can influence perioperative and postoperative outcomes. However, the relationship between obesity and treatment-related perioperative and short-term postoperative morbidity after colorectal resections is still subject to debate. Study: Patients were selected from the DCRA, a population-based audit including 83 hospitals performing colorectal cancer (CRC) surgery. Data regarding primary resections between 2009 and 2016 were eligible for analyses. Patients were subdivided into six categories: underweight, normal weight, overweight and obesity class I, II and III. Results: Of 71,084 patients, 17.7% with colon and 16.4% with rectal cancer were categorized as obese. Significant differences were found for the 30-day overall postoperative complication rate (p < 0.001), prolonged hospitalization (p < 0.001) and readmission rate (colon cancer p < 0.005; rectal cancer p < 0.002) in obese CRC patients. Multivariate analysis identified BMI ≥30 kg/m2 as independent predictor of a complicated postoperative course in CRC patients. Furthermore, obesity-related comorbidities were associated with higher postoperative morbidity, prolonged hospitalization and a higher readmission rate. No significant differences in performance were observed in postoperative outcomes of morbidly obese CRC patients between hospitals performing bariatric surgery and hospitals that did not. Conclusion: The real-life data analysed in this study reflect daily practice in the Netherlands and identify obesity as a significant risk factor in CRC patients. Obesity-related comorbidities were associated with higher postoperative morbidity, prolonged hospitalization and a higher readmission rate in obese CRC patients. No differences were observed between hospitals performing bariatric surgery and hospitals that did not

Patients with a Ruptured Abdominal Aortic Aneurysm Are Better Informed in Hospitals with an "EVAR-preferred" Strategy: An Instrumental Variable Analysis of the Dutch Surgical Aneurysm Audit

BACKGROUND: While several observational studies suggested a lower postoperative mortality after minimal invasive endovascular aneurysm repair (EVAR) in patients with a ruptured abdominal aortic aneurysm (RAAA) compared to conventional open surgical repair (OSR), landmark randomized controlled trials have not been able to prove the superiority of EVAR over OSR. Randomized controlled trials contain a selected, homogeneous population, influencing external validity. Observational studies are biased and adjustment of confounders can be incomplete. Instrumental variable (IV) analysis (pseudorandomization) may help to answer the question if patients with an RAAA have lower postoperative mortality when undergoing EVAR compared to OSR. METHODS: This is an observational study including all patients with an RAAA, registered in the Dutch Surgical Aneurysm Audit between 2013 and 2017. The risk difference (RD) in postoperative mortality (30 days/in-hospital) between patients undergoing EVAR and OSR was estimated, in which adjustment for confounding was performed in 3 ways: linear model adjusted for observed confounders, propensity score model (multivariable logistic regression analysis), and IV analysis (two-stage least square regression), adjusting for observed and unobserved confounders, with the variation in percentage of EVAR per hospital as the IV instrument. RESULTS: 2419 patients with an RAAA (1489 OSR and 930 EVAR) were included. Unadjusted postoperative mortality was 34.9% after OSR and 22.6% after EVAR (RD 12.3%, 95% CI 8.5-16%). The RD adjusted for observed confounders using linear regression analysis and propensity score analysis was, respectively, 12.3% (95% CI 9.6-16.7%) and 13.2% (95%CI 9.3-17.1%) in favor of EVAR. Using IV analysis, adjusting for observed and unobserved confounders, RD was 8.9% (95% CI -1.1-18.9%) in favor of EVAR. CONCLUSIONS: Adjusting for observed confounders, patients with an RAAA undergoing EVAR had a significant better survival than OSR in a consecutive large cohort. Adjustment for unobserved confounders resulted in a clinical relevant RD. An "EVAR preference strategy" in patients with an RAAA could result in lower postoperative mortality

Colorectal cancer surgery for obese patients:Financial and clinical outcomes of a Dutch population-based registry

Background and Objectives The objective of this study was to explore the association among adverse events, body mass index (BMI), and hospital costs after colorectal cancer surgery in a country with an intermediate BMI distribution. Methods All colorectal cancer procedures in 29 Dutch hospitals listed in a 2010-2012 population-based database and with a BMI &gt; 18.5 were included (n = 8687). Hospital costs were measured uniformly and based on time-driven activity-based costing. The BMI classification of the World Health Organization was used. Results Patients in obesity classes 1 (23.6% [after risk-adjustment OR 1.245, CI 1.064-1.479, P = 0.007]) and =2 (28.1% [after risk-adjustment OR 1.816, CI 1.382-2.388, P &lt; 0.001]) were associated with more severe complications and higher hospital costs (€14,294, +9.6%, after risk-adjustment +7.9%, P &lt; 0.001; and €15,913 +22.0%, after risk-adjustment +21.2%, P &lt; 0.001, respectively) than normal weight patients (20.8% and €13,040, respectively). Pre-obese patients had significantly lower mortality rates (2.7%, after risk-adjustment, OR 0.756, CI 0.577-0.991, P = 0.042) than normal-weight patients (3.9%). Conclusions Obese surgical colorectal cancer patients in a country with an intermediate BMI distribution are associated with a significant increase in hospital costs because these patients suffer from more severe complications. This is the first study to provide evidence for the "obesity-paradox" for mortality in colorectal cancer surgery