The relationship between procedure volume and outcomes has long been recognized: studies have concluded that patients operated on by high-volume surgeons at high-volume hospitals have improved outcomes.1,2 This paradigm is also associated with ovarian cancer outcomes. But what affect does adherence to evidence-based guidelines have on these statistics?
Jason D. Wright, MD, and colleagues at the Columbia University College of Physicians and Surgeons, in New York City, sought to determine whether strict adherence to quality metrics by hospitals could explain the association between hospital volume and ovarian cancer survival.3
Details of the study
Using the National Cancer Database (NCD), the research team identified 100,725 patients at 1,268 hospitals who were treated for invasive epithelial ovarian cancer between 2004 and 2013. Hospitals were stratified by annual case volume into quintiles: low-volume (≤2 cases; n = 299 [23.6%]), low-intermediate–volume (2.01–5 cases; n = 465 [36.7%]), intermediate-volume (5.01–9 cases; n = 157 [12.4%]), high-intermediate–volume (9.01–19.9 cases; n = 194 [15.3%]), and high-volume (≥20 cases; n = 153 [12.1%]).3
To measure quality, the authors defined hospital-level rates of 5 metrics based on clinical guidelines3:
- lymph node dissection performed for patients with stage I–IIIB tumors
- performance of omentectomy or cytoreduction for patients with advanced stage tumors
- use of chemotherapy among patients with early-stage, high-risk tumors
- omission of chemotherapy for women with early-stage, low-risk tumors
- use of chemotherapy (either neoadjuvant or adjuvant) for women with advanced-stage disease.
For each metric, the authors determined the rate of hospital-level compliance for all study-eligible patients. Then a composite variable of overall quality was derived using all 5 metrics. Based on the overall quality metric, hospitals were stratified into quartiles: low-quality, medium-low–quality, medium-high–quality, and high-quality.3
Hospital-level adjusted 2- and 5-year survival rates were compared based on volume and adherence to quality metrics.3
2017 Update on ovarian cancer
Trends and conclusions
Researchers found that compliance with quality metrics generally increased with hospital volume. Trends of increased compliance were observed with lymph node dissection for early-stage tumors, cytoreduction for advanced-stage tumors, and use of chemotherapy for advanced-stage tumors. No trends were evident for use of chemotherapy for high-risk, early-stage tumors. By contrast, a trend for higher-volume hospitals to administer chemotherapy for low-risk, early-stage tumors was discovered. Adherence with the composite overall quality metric was noted in 64.2% of low-volume centers and increased with each volume category to 82.2% at the highest-volume hospitals.3
Study results indicated that survival increased with increasing hospital volume and with adherence to the quality metrics. The association between volume and quality was then examined. For each volume category, survival increased with increasing adherence to the quality metrics. In the highest-volume group, 2-year adjusted survival rose from 75.5% (95% confidence interval [CI], 73.2%–77.8%) at the lowest-quality hospitals, to 78.6% (95% CI, 78.0%–79.1%) at the highest-quality hospitals. Similar trends were found for intermediate-volume hospitals and for 5-year survival. However, the relationship between adherence to quality metrics and survival was less consistent for the low-, low-intermediate–, and high-intermediate–volume hospitals.3
The authors concluded that both hospital volume and adherence to quality metrics are associated with survival for ovarian cancer. Even though survival rates are improved at low-volume hospitals that are highly adherent to quality metrics, their survival rates are still lower than high-volume hospitals.