Measures of physical fitness and postoperative mortality in patients with colorectal cancer: national cohort study

This is the authors' abstract. We don't add key points for this paper.

Background Measures of physical fitness are essential for case mix adjustment when comparing surgical outcomes between patient groups, surgical approaches, and healthcare providers. Commonly used measures include clinician-reported American Society of Anesthesiologists (ASA) grade and Eastern Cooperative Oncology Group (ECOG) performance status, as well as the Secondary Care Administrative Records Frailty (SCARF) index, derived from routinely collected administrative hospital data. This study compared how these measures of physical fitness, perform for case mix adjustment of postoperative colorectal cancer mortality. Methods All patients diagnosed with colorectal cancer (CRC) between April 2017 and March 2022 in the English and Welsh National Health Service who underwent surgery were included. The primary outcome was 90-day postoperative mortality. Using an established risk-adjustment model, different combinations of ASA grade, performance status, and the SCARF index were added to create eight models for 90-day mortality risk adjustment. Model performance was compared with a full model including all three measures of physical fitness. The basic model included no measures of physical fitness. The scaled Brier score (SBS) measured overall model performance and the C-statistic measured discriminatory ability. Results Among 91 957 patients, 90-day mortality was 2.8%. A model including both ASA grade and performance status achieved equivalent performance (SBS 0.092; C-statistic 0.833 (95% confidence interval (c.i.) 0.825 to 0.841)) to the full model (SBS 0.092; C-statistic 0.834 (95% c.i. 0.827 to 0.842)). The basic model with only performance status was slightly inferior (SBS 0.076; C-statistic 0.822 (95% c.i. 0.814 to 0.830)) to the basic model with only ASA grade (SBS 0.084; C-statistic 0.827 (95% c.i. 0.819 to 0.835)). Conclusion Performance status and ASA grade together accurately adjust for physical fitness when risk adjusting postoperative mortality in patients with CRC. When only one measure is available, performance status or ASA grade alone is suitable to support risk-adjusted hospital benchmarking.