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Examining Disparities in Route of Surgery and Postoperative Complications in Black Race and Hysterectomy

Alexander, Amy L., MD, MS; Strohl, Anna E., MD, MA; Rieder, Stephanie, MD, PhD; Holl, Jane, MD, MPH; Barber, Emma L., MD, MS

doi: 10.1097/AOG.0000000000002990
Contents: Health Disparities: Original Research
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OBJECTIVE: To estimate the associations among race, route of hysterectomy, and postoperative complications among women undergoing hysterectomy for benign indications.

METHODS: A cohort study was performed. All patients undergoing hysterectomy for benign indications, recorded in the National Surgical Quality Improvement Program and its targeted hysterectomy file in 2015, were identified. The primary exposure was patient race. The primary outcome was route of hysterectomy and the secondary outcome was postoperative complication. Associations were examined using both bivariable tests and logistic regression.

RESULTS: Of 15,136 women who underwent hysterectomy for benign indications, 75% were white and 25% were black. Black women were more likely to undergo an open hysterectomy than white women (50.1% vs 22.9%; odds ratio [OR] 3.36, 95% CI 3.11–3.64). Black women had larger uteri (median 262 g vs 123 g; 60.7% vs 25.6% with uterus greater than 250 g), more prior pelvic surgery (58.5% vs 53.2%), and higher body mass indices (32.7 vs 30.4). After adjusting for these and other clinical factors, black women remained more likely to undergo an open hysterectomy (adjusted OR 2.02, 95% CI 1.85–2.20). Black women experienced more major complications than white women (4.1% vs 2.3%; P<.001) and more minor complications (11.4% vs 6.7%; OR 1.78, P<.001). Again these disparities persisted with adjustment (major adjusted OR 1.56, 95% CI 1.25–1.95; minor adjusted OR 1.27, 95% CI 1.11–1.47).

CONCLUSIONS: Black women undergo a higher proportion of open hysterectomy and experience more major and minor postoperative complications. These differences persisted even after adjusting for confounding medical, surgical, and gynecologic factors.

Black women undergoing hysterectomy for benign indications undergo a higher proportion of open surgery and have more surgical complications when compared with white women.

Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Northwestern University Feinberg School of Medicine, the Robert H. Lurie Comprehensive Cancer Center, Northwestern University, and the Center for Healthcare Studies, Institute for Public Health in Medicine, Chicago, Illinois.

Corresponding author: Emma L. Barber, MD, MS, Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Northwestern University, Suite 05-2168, Chicago, IL 60611; email: emma.barber@northwestern.edu.

Supported by National Institutes of Health K12 HD050121-12.

Financial Disclosure The authors did not report any potential conflicts of interest.

Presented at the annual meeting of the Society of Gynecologic Oncology, March 24–27, 2018, New Orleans, Louisiana.

The data used in the study are derived from a deidentified National Surgical Quality Improvement file. The American College of Surgeons has not verified and is not responsible for the analytic or statistical methodology used or the conclusions drawn from these data by the investigators.

Each author has confirmed compliance with the journal's requirements for authorship.

Peer reviews and author correspondence are available at http://links.lww.com/AOG/B205.

Hysterectomy is the second most common surgical procedure performed on women in the United States.1 Since the early 2000s there has been a trend toward performing hysterectomy using a minimally invasive approach—either laparoscopic or vaginal, because studies have shown lower costs, fewer complications, and faster recovery times.2 Racial disparities persist in the United States, particularly with regard to implementation of new medical care or novel surgical technology.3 Several studies have shown that black race, in particular, is associated with decreased odds of receiving minimally invasive hysterectomy in patients with either benign or cancerous conditions.4,5

Several recent papers suggesting disparities in the route of hysterectomy have used secondary data sets that do not account for differences in patient populations.6–8 In particular, black women have two to three times risk of developing leiomyomas and, as a result, may have larger uteri, which could contribute to higher rates of open hysterectomies.9 Additionally, black women have higher rates of comorbidities such as obesity, diabetes, and hypertension, which may also contribute to higher rates of open hysterectomy.10,11 However, it is unclear whether disparities in route of hysterectomy persist for black women after accounting for patient factors such as body mass index (BMI, calculated as weight (kg)/[height (m)]2), uterine size, and prior pelvic surgery, all factors that may predispose a surgeon to perform an open hysterectomy, because these variables are not available in previously used data sets.

The objectives of this study are to determine the associations between race and route of hysterectomy and between race and postoperative complications among women undergoing hysterectomy for benign indications.

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METHODS

A cohort study was performed using prospectively collected data. Patients who underwent hysterectomy for any benign condition during 2015 were identified using International Classification of Diseases, 9th Revision codes and Current Procedural Terminology codes from the hysterectomy-specific file of the American College of Surgeons National Surgical Quality Improvement Program database. The institutional review board at Northwestern University reviewed this study and deemed it exempt from formal review because all data previously existed and were also deidentified.

Participation in the National Surgical Quality Improvement Program is voluntary and data are used by each participating hospital to track and measure surgical outcomes. Patient-level data such as demographics, perioperative measures, and postoperative outcomes are collected from electronic health records by specially trained clinical nurse reviewers. The data are periodically audited to maintain accuracy; however, it is important to note that data quality is excellent with participating institutions having only 2% intraobserver disagreement.12 Details of methods of data collection and reliability have been previously published.13

The primary outcome was route of hysterectomy, either minimally invasive (total laparoscopic, laparoscopically assisted vaginal, robotic, or vaginal hysterectomy) or open abdominal (total abdominal hysterectomy). The key exposure was patient race, either black or white. Surgical complications are secondary outcomes, which were defined as complications occurring from surgery up to 30 days after postoperatively. Similar to previously published studies, complications were classified as major or minor using the validated Clavien-Dindo grading scale; major complications were defined as grade 3 or higher and minor complications were defined as grade 2 or lower.14,15 Major complications included venous thromboembolism, myocardial infarction, stroke, pneumonia, deep or organ surgical site infection, fascial dehiscence, unplanned return to the operating room, renal failure, sepsis, cardiopulmonary arrest, intubation greater than 48 hours, and death. Minor complications included urinary tract infection, superficial wound infection, and blood transfusion. The diagnostic criteria used to define each of these complications are published in the National Surgical Quality Improvement Program data participant use file.16

Black patients were compared with white patients with respect to outcomes (hysterectomy route and complications). For bivariate comparisons, two-tailed t tests were used for continuous variables, Kruskal-Wallis for nonparametric variables, and Pearson χ2 test for categorical variables. The association between race and route of hysterectomy was analyzed using binary logistic regression for potential confounding. Confounders were defined a priori and were selected by considering clinical factors that may be taken into consideration when selecting route of hysterectomy including uterine weight, prior abdominal or pelvic surgery, endometriosis, BMI, age, and comorbidities.17–19 Although uterine weight can only be assessed after hysterectomy, it is the best measurement of uterine size. We tested uterine weight as a continuous, categorical (less than 250 g, 250–499 g, 500–100 g, and greater than 1,000 g) and binary (less than 250 g, 250 g or greater) variable. Modeling uterine weight in different ways resulted in little variation to the adjusted odds ratio and overall model fit. Ultimately, we chose to model uterine weight as a binary variable, either smaller or greater than 250 g, because most clinicians are able to approximate uterine size as large or small based on clinical examination before surgery and because 250 g has been used as a benchmark for higher reimbursement as a result of greater surgical complexity.20

In examining the association of black race and postoperative complications, a stratified analysis by route of hysterectomy was performed, because our first analysis showed an association between route of hysterectomy and both race and postoperative complications. For this model, confounders were again defined a priori by selecting clinical factors that are known to be associated with postoperative complications. The factors accounted for included prior abdominal surgery, prior pelvic surgery, endometriosis, BMI, age, comorbidities, procedures performed at the time of hysterectomy, and route of hysterectomy (open vs minimally invasive).14,15

Sensitivity analyses were performed to ensure our models were robust and sensitive to variations in how the uterine weight variable was categorized. First, given the large difference in median uterine weight of black compared with white women, we limited our analysis to women with uterine weight less than 250 g for both races to examine the possibility that uterine weight drives our adjusted analysis. Second, despite our large data set, we recognized that complications are rare events, in particular major complications. Therefore, propensity score matching was undertaken to create a cohort in which black and white participants were balanced on the same factors accounted for in our logistic regression: prior abdominal surgery, prior pelvic surgery, endometriosis, BMI, age, comorbidities, procedures performed at the time of hysterectomy, and, in our final analysis, route of hysterectomy (open vs minimally invasive). A P value of <.05 was considered significant for all analysis. STATA 14.1 was used for all analysis.

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RESULTS

A total of 15,316 patients were identified in the hysterectomy-specific file of the National Surgical Quality Improvement Program database. Patient demographic characteristics and past medical, surgical, and gynecologic history are shown in Table 1. The study population consisted of 74.9% (n=11,330) white and 25.1% (n=3,806) black patients. Black patients were younger, had higher BMIs, were more likely to have diabetes and hypertension, had higher median uterine weights, and had higher incidence of prior abdominal surgery. However, white patients were more likely to have a diagnosis of endometriosis and have a history of prior pelvic surgery.

Table 1.

Table 1.

Overall, more patients underwent minimally invasive hysterectomy (n=10,634 [70.3%]) than open hysterectomy (n=4,502 [29.7%]). Black women underwent a higher proportion of open hysterectomy (50.1%) compared with white women (22.0%) (odds ratio [OR] 3.36, 95% CI 3.11–3.64). After using a logistic regression to adjust for the factors associated with the selection of open hysterectomy, regardless of race, black women still had twice the odds of having an open hysterectomy compared with white women (Table 2). When the analysis was limited to only women with small uterine size (weight less than 250 g), black women remained at significantly higher odds of undergoing open hysterectomy (adjusted OR 1.84, 95% CI 1.61–2.11; Table 3).

Table 2.

Table 2.

Table 3.

Table 3.

A larger proportion of black women experienced complications when undergoing hysterectomy compared with white women, although stratified analysis showed that the proportion varied by type of hysterectomy (Table 4). When considering all modes of hysterectomy, black women experienced more total complications (14.1% vs 8.6%, P<.001), more major complications (4.1% vs 2.4%, P<.001), and more minor complications (11.4% vs 6.7%, P<.001). When examining patients who underwent vaginal hysterectomy, there were no differences in the proportion of women who had complications for black compared with white women, although there was a small number of complications. When examining only open hysterectomy, black women had greater number of minor complications (16.9% vs 11.3%, P<.001). Lastly, when women underwent laparoscopic hysterectomy, black women had more major complications when compared with white women (3.3% vs 1.8%, P<.001).

Table 4.

Table 4.

To adjust for factors that might place a patient at higher odds of developing a complication, a logistic regression was performed (Table 5). The regression showed that after adjustment for clinical factors, black women still had higher odds of postoperative complications, although the odds were decreased (major adjusted OR 1.56, CI 1.25–1.95, minor adjusted OR 1.27, CI 1.11–1.47).

Table 5.

Table 5.

In the propensity score–matched cohort analysis, there were no significant differences in patient characteristics that persisted after nearest neighbor matching (all P values >.05) between the matched cohort of black and white women (Table 6). Regression performed within this cohort largely confirmed the findings from the multivariable logistic regression: black women remained at increased odds of minor complications (OR 1.22, 95% CI 1.03–1.44) and increased odds of all complications (OR 1.25, 95% CI 1.08–1.46). However, in the matched cohort, there was no significant difference in the odds of experiencing major complications for black compared with white women.

Table 6.

Table 6.

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DISCUSSION

Our data are concordant with prior studies that demonstrate a disparity in the route of hysterectomy for black women. These findings also support the hypothesis that there may be clinical differences between white and black women that influence the surgeon's choice of hysterectomy route, in particular uterine size. However, even after adjusting for these important differences, black women had persistently higher odds of undergoing open hysterectomy. Black women also experienced more complications when undergoing any hysterectomy, which decreased but were not eliminated when adjusting for route of hysterectomy.

Prior investigation into complications from hysterectomy by Mehta et al21 identified that black race was associated with a higher rate of complications. This same analysis identified that minimally invasive hysterectomy was also associated with lower complications; however, the study did not investigate whether minimally invasive hysterectomy mitigated complication rates specifically for women of black race. The findings from our analysis help to bridge this gap in knowledge. Some of the postoperative complications experienced by black women are likely attributable to the fact that black women are more likely to undergo an open hysterectomy. However, because black race is still associated with a higher odds of complications, even when adjusting for hysterectomy route, there are other contributing factors that warrant further investigation.

One possible explanation for our findings is that women of minority race might have disparate access to gynecologic care. Ranjit et al7 attempted to answer this question by examining women of equivalent insurance and, therefore, presumably equal access to care. Black women still had greater odds of undergoing an open hysterectomy; however, the study did not fully take into consideration patient-level factors. In another study by Price et al,6 a small sample size of patients from three hospitals with high rates of minimally invasive hysterectomy found that black women did not have increased odds of having an open hysterectomy when controlling for other factors, including uterine size. The findings of Price et al suggest that access to care and quality of hospital care may be important factors to explore.

The strength of this study is the reliable, accurate database that is the source of data and which have been used to assess postoperative complications from hysterectomy and other surgical procedures for many other studies.15,22,23 The database provided data for a large sample of patients from many different hospitals and included patient-level medical information collected specifically for the use of examining postoperative outcomes. The addition of the targeted hysterectomy file within National Surgical Quality Improvement Program allowed for adjustment of important patient-level factors such as uterine size, obesity, and comorbidities not previously available in other secondary data set studies, yet factors that many gynecologic surgeons take into consideration in their decision-making about route of hysterectomy.

Limitations of the study include the potential for unmeasured bias. There may be other individual, system, or environmental factors that predispose black women to undergo open hysterectomy or to have more postoperative complications. Specifically, no studies about patient preference of surgeon, hospital, or route of hysterectomy have been published. Additionally, the exact hospital where each hysterectomy was performed is not available in the database. Indeed, there may be regional or geographic and practice patterns where black women are more or less likely to receive care for conditions requiring a hysterectomy. However, this study suggests that, regardless of local practice patterns, minimally invasive hysterectomy should be given greater consideration, especially when deciding the route of hysterectomy surgery for black women. Lastly, the database gives no information regarding surgeon volume or years of experience, which may be important contributors to complication rates and may additionally provide insight into the physicians who are caring for black women.

Although open hysterectomy and postoperative complications are also associated, this association alone does not explain the increased odds of complications experienced by black women, as demonstrated by the findings. System-level factors may contribute to black women receiving less guideline-concordant care and, thereby, resulting in more postoperative complications necessitating further investigation. This study suggests that an important step to reduce the disparity in route of surgery and postoperative complications is to increase access to and use of minimally invasive surgery. However, future research needs to explore other contributing factors.

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