Univariable analysis of factors evaluated for an association with grade 2 or higher complications is shown in Table 1. Two models predicting the occurrence of complications were created: a counseling model and a global model. The counseling model considered mainly patient factors to provide patients an estimation of operative morbidity before surgery. As shown in Table 3, five variables were significant in the multivariable counseling model using grade 2 or higher complications as the end point. When using grade 3 or higher complications as the end point, creatinine more than 1.5 mg/dL (odds ratio [OR] 2.9) was a strong predictor in a multivariable model that included this variable along with preoperative white blood cells and pulmonary dysfunction (P<.01; data not shown).
The intent of the global model was to identify process-of-care factors that, when controlled for by patient factors, could be modified for the purposes of quality improvement. Using grade 2 or higher complications as the end point, eight predictors were significant in multivariable modeling (Table 3). Preoperative creatinine more than 1.5 mg/dL (OR 3.0; P<.01), body mass index (BMI, calculated as weight (kg)/[height (m)]2) 50 or more (OR 2.7; P<.03), estimated blood loss (OR 1.6 per doubling; P<.001), and preoperative white blood cells (OR 1.8 per doubling; P<.03) were strong predictors of grade 3 or higher complications. Elevated creatinine was present in 11% of patients with severe complications. An existing diagnosis of diabetes had been made in 35% of the 55 patients with preoperative creatinine more than 1.5 mg/dL, and an additional 11% had preoperative hyperglycemia without a diagnosis of diabetes. However, hyperglycemia in the setting of undiagnosed diabetes was not significant in any multivariable model.
In both models surgical approach and use of para-aortic lymphadenectomy were powerful predictors of grade 2 or higher complications. Patients who underwent laparotomy were four times more likely to have a grade 2 or higher complication compared with patients who underwent minimally invasive surgery. A pelvic and para-aortic lymphadenectomy was associated with a doubling of the complication rate. Surgical complexity also was significant. Patients requiring additional major procedures related to the endometrial cancer diagnosis, such as splenectomy, bowel resection, or diaphragmatic resection (grade 4 surgical complexity), were 2.7-times more likely to experience a grade 2 or higher complication compared with those with hysterectomy and bilateral salpingo-oophorectomy only (grade 1 surgical complexity). The predicted probability of a grade 2 or higher complication from the model ranged from 0.01 to 0.97. Among the patients with a predicted probability of a grade 2 or higher complication of 10% or less, 10–20%, 20–30%, 30–40%, 40–50%, and more than 50%, the proportions of patients who actually experienced a grade 2 or higher complication were 9.3%, 13.6%, 22.8%, 34.1%, 42.8%, and 68.0%, respectively, demonstrating that our model performed well. Table 4 shows the effect that variations in patient characteristics and surgical approaches have on morbidity, using grade 2 or higher complications as the end point.
Given the strong association between surgical approach and morbidity, it was expected that corresponding costs also would be greater. In fact, multivariable analysis of modifiable risk factors (whether deep vein thrombosis [DVT] prophylaxis was provided, surgical approach and whether preoperative white blood cells were more than 11.1) in the entire cohort revealed that only surgical approach influenced 30-day cost: mean cost of laparotomy was $19,438, compared with $16,057 for laparoscopic or robotic, compared with $11,258 for the vaginal approach alone (P<.05). The highest costs were associated with conversions from minimally invasive approaches to laparotomy (mean $20,449, 95% CI $18,299–$22,598).
The cost of lymphadenectomy in patients with clinical stage I was evaluated by multivariable analysis, controlling for patient factors. Compared with patients at low risk who underwent hysterectomy alone, 30-day costs were 25% and 56% higher for patients who underwent hysterectomy and pelvic lymphadenectomy or hysterectomy plus pelvic and para-aortic lymphadenectomy, respectively (P<.01). Multivariable analysis of all significant predictors revealed that American Society of Anesthesiologists class more than 2, use of beta-blockers, a history of pulmonary dysfunction, grade 2 or higher complications, panniculectomy, estimated blood loss, and failure to use DVT prophylaxis were associated with higher 30-day costs (P<.05).
As gynecologic oncologists, our primary research efforts must no longer be limited to optimization of surgical technique, chemotherapy, and radiation therapy with the singular goal of improving cancer-related outcomes. Improving the value of care we provide, a function of oncologic outcomes, complications, and cost, must be the new “yardstick” by which we measure progress given ever-shrinking health care dollars in the setting of growing expenses. More importantly, quality improvement should be vigorously pursued because it is in the best interest of our patients.
This investigation has several important strengths. The relatively large size of our cohort permitted a valid analysis of many factors in a multivariable fashion. Predictors chosen for analysis were based on more than 130 in the National Surgical Quality Improvement Program database. Complications were reported according to the Expanded Accordion Classification, in which surgical complications are graded according to severity and level of intervention needed rather than simply comparing crude rates of “minor” and “major” complications. Our 30-day complication rate is qualified by the fact that 84% were at worst minor or moderate (grade 1 or 2). Nevertheless, this leaves room for improvement because even minor complications are associated with higher costs. Our rate of grade 3 or higher complications is comparable with other investigations (note that definitions of complications differed between investigations).17,18
The counseling model is useful to provide patients with an estimate of their personal complication rate before surgery. The global model provides an overall assessment of those variables associated with morbidity. Most striking is the fourfold increase in complications for patients who underwent laparotomy compared with minimally invasive surgery despite preservation of surgical quality. Others have reported equivalent survival and reduced length of stay with minimally invasive surgery.17,19,20 Given the increase in complication rates and 30-day costs, institutions with heterogeneous surgical approaches (including our own in the past) will be hard-pressed to justify continued routine use of laparotomy for patients with endometrial cancer.
Minimally invasive surgery fell out of the model when grade 3 and higher complications were used as the end point, suggesting that this approach was mainly responsible for reducing mild and moderate grade complications, particularly surgical site infections. In contrast, BMI 50 or higher was a significant predictor of grade 3 and higher complications, with an adjusted OR of 2.7. It is noteworthy that obesity up to a BMI of 50 (less than 30, 30–39, and 40–49 were analyzed separately) was not associated with increased morbidity in any model and provides encouragement that reducing the degree of obesity may be as important as obtaining ideal body weight.
Para-aortic lymphadenectomy was associated with a doubling in the complication rate and highlights the need to objectively define which patients derive oncologic benefit from lymphadenectomy.21,22 In contrast, we were unable to associate pelvic lymphadenectomy alone with untoward events. However, morbidity assessment was limited to 30 days; therefore, this investigation was not designed to detect long-term quality-of-life effects. Rates of lower extremity lymphedema with extended follow-up will be reported separately. In an analysis limited to clinical stage I patients to minimize bias, both pelvic and para-aortic lymphadenectomy resulted in significant cost increases; therefore, we feel strongly that unnecessary lymphadenectomy should be omitted.2
Most disappointing was the absence of modifiable process-of-care factors that could be potentially altered to improve outcomes in the global model. It appears that patient characteristics, such as American Society of Anesthesiologists class, BMI, or pulmonary dysfunction, and uncontrollable factors, such as operative complexity, dominated the model and obscured potential benefits of controllable factors, such as normothermia or mean arterial blood pressure. A strong and unexpected predictor of severe complications was preoperative creatinine more than 1.5 mg/dL, present in 11% of patients with severe complications. Renal insufficiency may be a surrogate for long-term systemic effects of hyperglycemia that impair healing or otherwise increase the risk of severe complications. Failure to use DVT prophylaxis also was predictive of cost. The use and method of DVT prophylaxis was variable in our practice in 1999, but today it is standardized across surgeons. This is one example of how quality assessment changes practice and improves patient care. Regarding the association of beta-blockers with higher cost, this is likely to be confounded by the high correlation between beta-blocker use and other high-risk characteristics.
A limitation of this investigation is that a relatively small proportion of patients underwent para-aortic lymphadenectomy via a minimally invasive approach. The extended laparotomy incision required for para-aortic lymphadenectomy would be expected to increase morbidity in and of itself. Therefore, it remains to be determined whether these models are valid when laparoscopic or robotic approaches are used exclusively. For example, we reported no transfusions or grade 3 complications in a prospective series of patients who underwent laparoscopic extraperitoneal para-aortic dissection.23
As reimbursement for surgical complications begins to be curtailed in 2012, trends of referring obese or Medicare patients to tertiary care centers may expand to those patients known to be at higher risk for even minor complications to reduce expenses. Proper risk adjustment therefore is paramount, as shown in Table 4. This report is an initial effort to define proper risk adjustment in patients with endometrial cancer. It is critical that our findings be tested in other high-volume tertiary care institutions that provide expert oncologic care to women with endometrial cancer–analyses of morbidity and cost cannot be performed without also considering oncologic outcomes. With the changing landscape of new surgical techniques and treatment algorithms, it will be necessary to continually reassess factors associated with morbidity for continued quality improvement.
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© 2012 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.
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