Influence of department volume on survival for ovarian cancer: results from a prospective quality assurance program of the Austrian Association for Gynecologic Oncology

Abstract

Objective: The Austrian Association for Gynecologic Oncology initiated in 1998 a prospective quality assurance program for patients with ovarian cancer. The aim of this study was to evaluate factors predicting overall survival especially under consideration of department volume.

Methods: All Austrian gynecological departments were invited to participate in the quality assurance program. A questionnaire was sent out that included birth date, histology, date of diagnosis, stage, and basic information on primary treatment. Description of comorbidity was not requested. Patient life status was assessed in a passive way. We did record linkage between each patient's name and birth date and the official mortality data set collected by Statistics Austria. No data were available on progression-free survival. Patients treated between January 1, 1999 and December 31, 2004 were included in the analysis. Mortality dates were available to December 31, 2006. Data were analyzed by means of classical statistical methods. Cut-off point for departments was 24 patients per year.

Results: A total of 1948 patients were evaluable. Approximately 75% of them were treated at institutions with fewer than 24 new patients per year. Patient characteristics were grossly similar for both department types. Multivariate analysis confirmed established prognostic factors such as International Federation of Gynecologists and Obstetricians (FIGO) stage, lymphadenectomy, age, grading, and residual disease. In addition, we found small departments (<24 patients per year) to have a negative effect on overall survival (hazards ratio, 1.38: 95% confidence interval, 1.2-1.7; and P < 0.001).

Conclusions: The results indicate that in Austria, rules prescribing minimum department case load can further improve survival for patients with ovarian cancer.