Materials and Methods
We constructed a decision tree to compare outcomes of laparoscopic hysterectomy with morcellation with abdominal hysterectomy for women with an enlarged uterus because of presumed benign leiomyomata ( Figure 1 ). We assessed a hypothetical cohort of 100,000 premenopausal women, because approximately 200,000 hysterectomies are performed for leiomyomata annually in the United States. It made clinical sense that roughly one-half of those procedures could involve uteri large enough to require morcellation if considered for laparoscopic hysterectomy. The decision tree model was constructed using Excel 2010 (Microsoft Corporation, Redmond, WA) and TreePlan (TreePlan Software, San Francisco, CA).
Women who underwent both laparoscopic and abdominal hysterectomy were at risk for potential surgical complications, each represented as unique and independent health states in the model. Morbidity and mortality outcomes were evaluated over a 5-year time horizon. This study was considered exempt from review by the Institutional Review Board at the University of North Carolina at Chapel Hill because it involved analysis of existing published data. Three of the authors (S.W., S.R., and M.S.) were responsible for analyzing data.
Base-case estimates and ranges for each parameter and transition probabilities that govern movement between branches in the decision tree were determined by published literature review ( Table 1 ). In the selection of estimates, preference was given to higher-quality studies and more recent publications that reflected advances in surgical practice. Surgical complications in the model included transfusion, abdominal wound infection, vaginal cuff dehiscence, venous thromboembolism, incisional hernia, leiomyosarcoma, death from leiomyosarcoma, and death from hysterectomy. Febrile episodes and vaginal cuff infections were considered but were believed to be better represented by identifiable and more objective diagnoses, wound infection, and cuff dehiscence. Major visceral and vascular adverse events were not included because they are rare and not significantly different between laparoscopic and abdominal hysterectomy.
| Parameter | Laparoscopic hysterectomy estimate | Range | Abdominal hysterectomy estimate | Range | Sources | Level of evidence a |
|---|---|---|---|---|---|---|
| Transfusion | 0.024 | 0.013–0.035 | 0.047 | 0.043–0.047 | Nieboer et al | I |
| Wallenstein et al | ||||||
| Wiser et al | ||||||
| Wound infection | 0.015 | 0.00055–0.015 | 0.063 | Not varied | Nieboer et al | I |
| Wallenstein et al | ||||||
| Vaginal cuff dehiscence b | 0.0064 | 0.0002–0.0089 | 0.0029 | 0.0015–0.006 | Hur et al | II-2 |
| Koo et al | ||||||
| Ucella et al | ||||||
| Venous thromboembolism | 0.0069 | 0.003–0.009 | 0.0084 | 0.0072–0.0084 | Wallenstein et al | I |
| Wiser et al | ||||||
| Nieboer et al | ||||||
| Ritch et al | ||||||
| Harrki-Siren et al | ||||||
| Hernia c | 0.0071 | 0.0014–0.09 | 0.0880 | 0.045–0.098 | Brown and Goodfellow | I |
| Bickenbach et al | ||||||
| Le Huu Nho et al | ||||||
| Hussain et al | ||||||
| Swank et al | ||||||
| Occult leiomyosarcoma incidence d | 0.0012 | 0.0007–0.0049 | — | — | Seidman et al | II-3 |
| Leibsohn et al | ||||||
| Parker et al | ||||||
| Kamikabeya et al | ||||||
| Leung and Terzibachian | ||||||
| Procedure-related death | 0.00012 | 0.000096–0.00012 | 0.00032 | 0.00032–0.00038 | McPhersonet al e | II-3 |
| Wallenstein et al f | ||||||
| Wiser et al | ||||||
| Death from leiomyosarcoma g | 0.72 | Not varied | 0.59 | Not varied | Kosary | III |
a US Preventative Services Task Force level of evidence for highest-quality source
b A weighted average was used because the incidence was low and the difference varied between groups among candidate studies
c It was assumed that most candidate fibroid uteri that were large enough to need morcellation during laparoscopic hysterectomy would require a vertical midline incision if removed by laparotomy. The rate of incisional hernia after hysterectomy was not readily identified in the gynecologic literature and thus was extrapolated from general surgery reports. The incidence of hernia with a transverse incision that was reported in a Cochrane review was used for the lower estimate in sensitivity analysis
d The same estimate and range was used for the incidence of occult leiomyosarcoma in laparoscopic and abdominal hysterectomy
e Used only for the abdominal hysterectomy estimate
f Used only for the laparoscopic hysterectomy estimate
g The abdominal hysterectomy group was assigned the 5-year death rate for International Federation of Obstetrics and Gynecology stage I-II leiomyosarcoma and laparoscopic hysterectomy was assigned the 5-year death rate for stage III leiomyosarcoma according to Surveillance, Epidemiology, and End Results reports.
Mortality rates because of hysterectomy were reflected in the literature as a short-term outcome and were not categorized by a specific cause (eg, fatal embolic event). With the exclusion of older studies that were conducted when safety and prophylactic measures (eg, infection, venous thromboembolism) were different from modern practice, estimates of 0.00012 (laparoscopic hysterectomy) and 0.00032 (abdominal hysterectomy) were derived from 3 larger and more recent series.
In terms of occult malignancy, we focused on leiomyosarcoma in particular because it mimics benign myomatous disease. Other more rare uterine mesenchymal tumors have diverse biologic behavior, and the impact of morcellation on these tumors is unknown. Cervical cancer is almost always a known preoperative diagnosis, and the risk of tissue dissemination appears to be less serious with endometrial cancer. Ten sources were considered regarding the incidence of leiomyosarcoma among women who undergo hysterectomy for presumed fibroid tumors ( Table 2 ). Quality and the degree to which the study population mirrored that for our decision analysis was evaluated based on year of publication, menopausal status, number of subjects, geographic location, and pathologic criteria that were used to determine leiomyosarcoma diagnosis. An estimate of 0.0012 (6/5084 cases) was derived from what were considered the 4 highest quality sources that reported mean estimates of 0.0008, 0.0007, 0.0009, and 0.0023. The range for sensitivity analysis included those sources with sample size >1000:0.0007 to 0.0049.
| Study | Publication year | Study years | Country | Age, y | Leiomyosarcoma Cases, n | Total patients, n | Rate of leiomyosarcoma |
|---|---|---|---|---|---|---|---|
| Leibsohn et al | 1990 | 1983-1988 | United States | 36-62 | 7 | 1429 | 0.0049 |
| Reiter et al | 1992 | 1986-1989 | United States | 42 (mean) | 0 | 104 | 0.0 |
| Parker et al a | 1994 | 1988-1992 | United States | 22-86 | 1 | 1332 | 0.0008 |
| Takamizawa et al | 1999 | 1983-1997 | Japan | 26-75 | 1 | 923 | 0.0011 |
| Sinha et al a | 2008 | 1998-2005 | India | 34 (mean) | 2 | 505 | 0.0040 |
| Kamikabeyaet al | 2010 | 1987-2008 | Brazil | Not reported | 1 | 1364 | 0.0007 |
| Rowland et al b | 2011 | 2006-2011 | United States | Not reported | 3 | 1115 | 0.0027 |
| Leung and Terzibachian | 2012 | 1999-2005 | France | 34-77 | 3 | 1297 | 0.0023 |
| Seidman et al a,c | 2012 | 1999-2010 | United States | Not reported | 1 | 1091 | 0.0009 |
| Theben et al | 2013 | 2005-2010 | Germany | 28-81 | 2 | 1584 | 0.0013 |
Leiomyosarcoma mortality estimates were derived from Surveillance, Epidemiology, and End Results reports. First, we assumed that women with metastatic disease generally would be identified preoperatively and not be candidates for our hypothetical cohort. In rare cases when it was not identified, surgical approach, with or without morcellation, would not change their stage (IV) nor impact overall survival, which would be driven by the distant metastases. Therefore, occult leiomyosarcoma that was detected at the time of hysterectomy would be represented in the model by an International Federation of Obstetrics and Gynecology stage I or II (confined to the pelvis) diagnosis, with a 5-year mortality rate of 0.59. Second, we assumed morcellation could lend the same prognosis as spontaneous cancer spread; thus, the laparoscopic group was assigned a stage III (extra-pelvic disease) prognosis, with a 5-year mortality rate of 0.72 (ie, all laparoscopic patients were given a worse prognosis than abdominal patients).
In the model, morcellation indicated the cutting of uterine tissue to facilitate laparoscopic removal. Data are lacking regarding safety differences between various morcellation techniques that prevented the stratification by type of morcellation. The few studies that demonstrate survival differences in patients with leiomyosarcoma who underwent surgery with and without morcellation include a heterogeneous set of extraction modalities.
Health state utilities capture health-related quality of life and are measured on a scale of 0-1, where 0 represents death and 1 represents 1 year of life in perfect health. Each year of life spent at that health state then can be quantified in quality-adjusted life years. Using published literature, we derived utility estimates for each health state represented in the model and the average duration of each health state ( Table 3 ).
| Parameter | Estimate | Range a | Duration, mo | Source |
|---|---|---|---|---|
| Hysterectomy for fibroid tumors b | 0.9 | 0.72–1.0 | 6 | O’Sullivan et al |
| Transfusion | 0.48 | 0.38–0.58 | 1 | Klarenbock et al |
| Wound infection | 0.607 | 0.49–0.73 | 1 | Chatterjee et al |
| Vaginal cuff dehiscence | 0.54 | 0.43–0.65 | 1 | Chatterjee et al |
| Venous thromboembolism | 0.8 | 0.64–0.96 | 12 | Spangler et al |
| Hernia | 0.77 | 0.62–0.92 | 24 | Hynes et al |
| Leiomyosarcoma (1st 6 months chemotherapy) c | 0.76 | 0.61–0.91 | 6 | Reichardt et al |
| Leiomyosarcoma progression (additional 6 months chemotherapy) d | 0.66 | 0.53–0.79 | 12 | Reichardt et al |
| Leiomyosarcoma progression (palliative care) e | 0.71 | 0.57–0.85 | 36 | Health Quality Ontario |
| Alive | 1.0 | Not varied | Varies | — |
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