Impact of Obesity on Clinical and Financial Outcomes of Minimally Invasive Hysterectomy for Benign Conditions.

This study identified 2,483 women who underwent benign minimally invasive hysterectomy between 2013–2019 by 114 unique surgeons. Laparoscopic approach was most performed (79.8%) followed by robotic (12.2%), and vaginal (8.0%). Patient and surgeon characteristics, stratified by BMI, are presented in Table 1 . Perioperative characteristics, stratified by BMI, are presented in Table 2 . Compared with non-obese patients, OR time was significantly higher among patients with class I/II obesity (BMI 30–39) and highest among patients with class III obesity (BMI ≥ 40) ( P <0.001). There was no significant difference in LOS ( P =0.274) or total adverse perioperative events ( P =0.131) across different BMI categories. Hysterectomy was most expensive among patients with class III obesity (median= $13,857, P=0.003). Each additional minute in the OR increased charges by $47.89 (P <0.001). The impact of obesity and surgical approach on clinical and financial outcomes is presented in Table 3 . Obesity, and more so class III obesity, was a significant predictor of increased OR time and EBL. When stratified by surgical approach and compared with non-obese patients undergoing laparoscopic hysterectomy, patients with obesity undergoing vaginal hysterectomy had significantly less mean charges while patients with obesity undergoing robotic hysterectomy had significant higher mean charges. To examine and isolate the true impact of obesity on charges, a multivariate linear regression was performed and is presented in Table 4 . After adjusting for covariates, significant predictors of hysterectomy charges include route of surgery (vaginal only), year, surgical subspecialty, select surgical indications (hyperplasia without atypia and genetic prophylaxis), hospital, OR time, and LOS. Patient age, race/ethnicity, and resident participation had no significant effect on hysterectomy charges. Compared with non-obese patients undergoing laparoscopic hysterectomy, vaginal hysterectomy had a significant mean decrease in charges of $1,266.04 among non-obese patients (95% CI: −1771.05; −761.04) and a significant mean decrease in charges of $1,576.46 among patients with class I/II obesity (95% CI: −2203.58; −949.35). Laparoscopic and robotic hysterectomy approaches, regardless of BMI, were not significant predictors of charges. While hysterectomy performed by any sub-specialist was associated with an increase in charges compared with general gynecologists, the largest increase in charges was found when hysterectomy was performed by urogynecologists ($1,143.01, P<0.001). After adjusting for covariates, BMI was not a significant predictor of charges.

After approval from the Johns Hopkins University Institutional Review Board (IRB00211405), we performed a retrospective cohort analysis of all women undergoing minimally invasive hysterectomy (vaginal, laparoscopic, and robotic) across five affiliated hospitals from 2013 to 2019. We excluded women under the age of 18 and those with malignant indications. We obtained patient, perioperative, surgeon characteristics, and financial data, and then analyzed the impact of obesity on clinical and financial outcomes by hysterectomy approach. Patient characteristics extracted from electronic medical records included age at time of hysterectomy, race, BMI, year surgery performed, and payer type. Perioperative characteristics include EBL, length of stay (LOS), operating room (OR) time, uterine weight from pathology reports (grams), adverse perioperative events (blood transfusion, unintended organ injury, conversion to laparotomy, 30-day readmission, emergency department [ED] visit, and OR takeback), and hospital charges. Surgeon characteristics include surgeon subspecialty. OR time was calculated from time in-the-room to out-of-room, including time for induction, patient positioning, and extubation. Total charges levied by the institution to the payer reflect hospital-reported all-payer data. Charges were generated automatically by the hospital Cost Accounting System and include procedure cost, OR minutes, Anesthesia minutes, billable supplies, medications, room and board, imaging, and labs. Hysterectomy was categorized by surgical approach (laparoscopic, vaginal, robotic). BMI was stratified as: non-obese (BMI <30), class I/II obesity (BMI 30–39), and morbid or class III obesity (BMI ≥ 40). Primary outcomes were OR time, EBL, LOS, and hospital charges. Secondary outcomes were occurrence of adverse perioperative events. Descriptive statistics were reported as mean ± standard deviation or median with interquartile range. Because LOS, EBL, OR time, charges and uterine weight were non-normally distributed, a Kruskal-Wallis test was used to test statistical significance for continuous variables, whereas a chi-squared test was used for categorical variables. An unadjusted linear regression was conducted to examine the effects of obesity on primary outcomes, a multivariate logistic regression analysis was conducted to evaluate the effect of obesity on occurrence of adverse perioperative events, and a multivariate linear regression was conducted to examine the effect of obesity on charges. Regression was adjusted for surgical approach, age, surgery year, OR time, race/ethnicity, surgical indication, resident participation, surgeon subspeciality, specimen weight, surgical facility, LOS, and insurance type. Statistical analysis was performed using SPSS v21 (IBM Corporation, Armonk, NY) and two-tailed statistical significance was set at P <0.05.

The results from our cohort demonstrate that obesity appears to have a significant impact on the clinical outcomes of benign hysterectomy that is approach-dependent and most notable among patients with class III obesity. Obesity’s effect on charges appears to be mediated through non-patient factors such as OR time, LOS, hospital facility, and surgeon subspecialty. Consideration of these factors should guide gynecologists to minimize OR time, decrease LOS, and perform hysterectomy by vaginal route when able to decrease charges. Similar to previously published studies, we found obesity to be associated with increased OR time 4 , 5 , 6 and EBL 5 , 6 which was most pronounced in class III obesity. In addition to considering the effect of BMI on surgical exposure and access to deep pelvic structures, the difference in OR time may be related to non-operative variables. OR time in this study spans in-room to out-of-room time and thus is influenced by factors such as patient positioning, anesthesia induction, and airway management – which are known to be affected by BMI. 17 Furthermore, OR time was independently predictive of charges. In addition to operative efficiency, strategies including leading team huddles to review supply chain needs at the beginning of a case, 18 maintaining familiar teams, 19 performing parallel tasks in the OR, and reducing instruments on surgical trays 20 have been shown to reduce OR time 21 and may be incorporated. This study did not demonstrate a relationship between obesity and LOS, which is consistent with other data. 4 , 22 LOS was, however, predictive of charges, and efforts to reduce post-operative hospital stay through same-day-discharge initiatives 23 and continued implementation of Enhanced Recovery After Surgery protocols 24 is prudent and well-demonstrated. A minimally invasive approach to hysterectomy is safe and recommended in patients, including patients with obesity. In previous literature, the association between BMI and adverse outcomes is mixed with some data showing higher complication severity associated with a higher BMI 6 , 25 and other data demonstrating no difference. 5 In our cohort, there was no significant impact of BMI on any adverse perioperative outcomes, likely due to the very low occurrence rate of these events in our study sample. When stratified by BMI only, hysterectomy was most expensive among patients with class III obesity undergoing robotic hysterectomy. However, when accounting for covariates, hysterectomy performed laparoscopically or robotically appeared to neutralize the effect of obesity on charges. Factors such as uterine specimen size and surgical indication contribute to the degree of surgical difficulty and affect outcomes. 26 , 27 With the exception of surgery for genetic prophylaxis and hyperplasia without atypia, cases that may have had concomitant procedures or intra-operative frozen pathologic evaluation, neither specimen size nor surgical indication affected charges in our study. Furthermore, hysterectomy performed vaginally decreased charges for non-obese patients and for patients with class I/II obesity and, if feasible, should be considered for all patients. This aligns with ACOG’s preferred approach to benign hysterectomy. 12 This study has some limitations. It is retrospective and observational in nature, rendering it susceptible to selection bias as patients were not randomized by surgical approach. Concomitant procedures such as prolapse repair or oophorectomy were not identified in the database yet may confound results. Charges in health care are affected by many variables including reimbursement rates, fiscal year, and insurance coverage, and therefore may not represent true cost. Because of Maryland’s “All-Payer Model” of reimbursement where third-party payers reimburse hospitals for goods and services at a uniform annual rate, 28 charges in our study are thought to closely reflect the true cost of care. On the other hand, we recognized several strengths including the use of a large database, a multi-center study, and a diverse patient population that renders the results generalizable. Data from this study support the hypothesis that obesity affects clinical outcomes (OR time and EBL) of benign minimally invasive hysterectomy. This is most notable among patients with class III obesity. We found no difference in perioperative complications, LOS, or charges attributable to obesity. Strategies to decrease LOS and increase OR efficiency, coupled with thoughtful selection of surgical approach, should be implemented to decrease hysterectomy charges while upholding quality and safety.

In the United States (U.S), hysterectomy is the second most common surgery performed on reproductive age women after cesarean delivery. 1 Obesity, defined as body mass index (BMI) of ≥30 kg/m 2 , has been growing, affecting more than 40% of adult women, with 11.5% meeting criteria for class III obesity (BMI ≥40). 2 A high BMI has been associated with an increased risk of operative difficulty and perioperative morbidity. 3 At the national level, obesity was associated with longer operative times for hysterectomy in a study of 55,409 women regardless of approach (abdominal, laparoscopic, or vaginal). 4 Smaller studies have also found a higher BMI to increase operative time, estimated blood loss (EBL), and complication severity, 5 , 6 although not supported by other studies. 7 , 8 Well-established benefits of minimally invasive surgery, also observed in obese patients, include lower EBL, decreased post-operative pain, and shorter hospital stay. 9 , 10 Thus, the American College of Obstetricians and Gynecologists promote minimally invasive routes of hysterectomy whenever feasible. 11 , 12 An estimated 400,000 hysterectomies are performed annually in the U.S., only ~40% of which are performed minimally invasively. 13 While predictors of hysterectomy charges, such as surgical approach, age, operative time, EBL, insurance type, length of stay, fiscal year, and concomitant procedures have been previously identified, 14 the data evaluating the effect of high BMI are inconsistent. With U.S. health care spending projected to reach $6.2 trillion by 2028, 15 evaluating factors affecting charges for hysterectomy is essential. From a charges perspective, retrospective studies demonstrate that a robotic approach is more expensive than a laparoscopic approach. 16 However, no data exist evaluating the effect of BMI on charges for different minimally invasive hysterectomy approaches and across a broad sample of surgeons including general gynecologists, urogynecologists, gynecologic oncologists performing benign hysterectomy, and minimally invasive gynecologic surgeons (MIGS). Thus, this study aims to examine the impact of obesity on clinical and financial outcomes of benign minimally invasive hysterectomy.