Yoshio Haga1, Shinji Hato2, Masakazu Ikenaga3, Kazuyoshi Yamamoto4, Akira Tsuburaya5, Koichi Doi6, Koji Ikejiri7, Toshihiko Hirata8, Manabu Yamamoto9, Shinji Ishikawa10, Hitoshi Takeuchi11. 1. Institute for Clinical Research, National Hospital Organization Kumamoto Medical Center, 1-5 Ninomaru, Chuo-ku, Kumamoto, 8600008, Japan; Department of International Cooperation, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 8608556, Japan. Electronic address: epass2006@outlook.com. 2. Department of Surgery, National Hospital Organization Shikoku Cancer Center, 160 Kou, Minamiumemoto-machi, Matsuyama, 7910280, Japan. 3. Department of Surgery, Osaka Rosai Hospital, 1179-3 Nagasone-cho, Sakai, 5918025, Japan. 4. Department of Gastroenterological Surgery, National Hospital Organization Osaka National Hospital, 2-1-14 Hoenzaka, Chuo-ku, Osaka, 5400006, Japan. 5. Department of Gastroenterological Center, Yokohama City University Medical Center, 4-57 Urafune-cho Minami-ku, Yokohama, 232-0024, Japan. 6. Department of Surgery, Saiseikai Kumamoto Hospital, 5-3-1 Chikami, Minami-ku, Kumamoto, 861-4193, Japan. 7. Department of Gastroenterological Surgery, National Hospital Organization Kyushu Medical Center, 1-8-1 Jigyohama, Chuo-ku, Fukuoka 8108563, Japan. 8. Division of General Surgery, Japanese Red Cross Kumamoto Hospital, 2-1-1 Nagamine-minami, Higashi-ku, Kumamoto, 8618520, Japan. 9. Department of Gastroenterological Surgery, National Kyushu Cancer Center, 3-1-1 Notame, Minami-ku, Fukuoka, 8111395, Japan. 10. Department of Surgery, Kumamoto Regional Medical Center, 5-16-10 Honjo, Chuo-ku, Kumamoto 8600811, Japan. 11. Department of Surgery, National Hospital Iwakuni Clinical Center, 1-1-1 Atagomachi, Iwakuni, 7408510, Japan.
Abstract
BACKGROUND: Benchmarking of long-term surgical outcomes has rarely been attempted. We previously devised a prediction model for assessing the outcome of late survival after surgery, termed the Estimation of Postoperative Overall Survival for Gastric Cancer (EPOS-GC). This study was undertaken to validate EPOS-GC in an external data set. METHODS: A retrospective cohort study was conducted in 11 cancer care hospitals in Japan, analyzing a consecutive series of patients who underwent elective gastric cancer resection between April 2007 and March 2009. EPOS-GC consists of three tumor-related variables and three physiological variables. The primary endpoint was postoperative overall survival. The observed-to-expected (O/E) ratio of 5-year survival rates was defined as a metric of quality of care. The sample size for O/E was determined as 42. RESULTS: We included 2045 patients for analysis. The median (95% confidence interval) follow-up time was 5.1 (1.2-6.8) years for censored patients. Although EPOS-GC demonstrated a good discriminative power (Harrell's C-index, 95% confidence interval: 0.80, 0.79-0.83), the calibration plot revealed that EPOS-GC underestimated 5-year survival rates in the high-risk group. Therefore, we recalibrated the model with Cox's regression analysis. The recalibrated EPOS-GC showed a good calibration, preserving the high discriminative power (C-index, 95% confidence interval: 0.80, 0.78-0.82). The O/E among hospitals according to the recalibrated EPOS-GC ranged between 0.87 and 1.27. The O/E correlated with hospital volumes (Spearman's correlation = 0.76, n = 11, p = .006). CONCLUSION: EPOS-GC with recalibration can convey risk-adjusted quality assurance regarding late survival following gastric cancer resection.
BACKGROUND: Benchmarking of long-term surgical outcomes has rarely been attempted. We previously devised a prediction model for assessing the outcome of late survival after surgery, termed the Estimation of Postoperative Overall Survival for Gastric Cancer (EPOS-GC). This study was undertaken to validate EPOS-GC in an external data set. METHODS: A retrospective cohort study was conducted in 11 cancer care hospitals in Japan, analyzing a consecutive series of patients who underwent elective gastric cancer resection between April 2007 and March 2009. EPOS-GC consists of three tumor-related variables and three physiological variables. The primary endpoint was postoperative overall survival. The observed-to-expected (O/E) ratio of 5-year survival rates was defined as a metric of quality of care. The sample size for O/E was determined as 42. RESULTS: We included 2045 patients for analysis. The median (95% confidence interval) follow-up time was 5.1 (1.2-6.8) years for censored patients. Although EPOS-GC demonstrated a good discriminative power (Harrell's C-index, 95% confidence interval: 0.80, 0.79-0.83), the calibration plot revealed that EPOS-GC underestimated 5-year survival rates in the high-risk group. Therefore, we recalibrated the model with Cox's regression analysis. The recalibrated EPOS-GC showed a good calibration, preserving the high discriminative power (C-index, 95% confidence interval: 0.80, 0.78-0.82). The O/E among hospitals according to the recalibrated EPOS-GC ranged between 0.87 and 1.27. The O/E correlated with hospital volumes (Spearman's correlation = 0.76, n = 11, p = .006). CONCLUSION: EPOS-GC with recalibration can convey risk-adjusted quality assurance regarding late survival following gastric cancer resection.