Operative Severity Score (OSS): Operative severity, Peritoneal soiling, Operative urgency, and Cancer staging.
Logistic Regression Formula
ln[R/(1 − R)] = -9.167 + (0.338 × PS) + (0.308 × OSS)
Probability of Death (R) = 1 / (1 + e^-ln[R/(1 − R)])
Triage Cut-offs (Pinho et al.)
A CR-POSSUM predicted mortality ≥ 9.16% is strongly associated with the clinical need for immediate HDU/ICU admission (AUC 0.78).
Section 3
Pearls/Pitfalls
Utility vs Other Models
CR-POSSUM outperforms the generic P-POSSUM model specifically for colorectal cancer patients. P-POSSUM often underpredicts or overpredicts depending on the cohort, whereas CR-POSSUM maintains a closer O:E ratio (Observed vs Expected deaths).
When evaluating post-operative allocation to HDU/ICU, CR-POSSUM alone has demonstrated a better discriminative capacity (AUC 0.78) than the Surgical Apgar Score or SAS (AUC 0.67), due to its inclusion of preoperative markers and staging.
Although CR-POSSUM tends to overestimate absolute mortality in low-risk Spanish cohorts (where operative mortality is ~1.5%), its discriminatory power to separate high-risk and low-risk groups remains highly significant (AUC ~75%).
Section 4
Evidence Appraisal
Primary References
Validity of the CR-POSSUM model in surgery for colorectal cancer in Spain (CCR-CARESS study) and comparison with other models to predict operative mortality.
Baré M et al. • BMC Health Serv Res. 2018;[https://doi.org/10.1186/s12913-018-2839-x](https://doi.org/10.1186/s12913-018-2839-x)
Comparison of P-POSSUM and Cr-POSSUM Scores in Patients Undergoing Colorectal Cancer Resection.
Horzic M et al. • Arch Surg (JAMA Surgery). 2007;[https://jamanetwork.com/journals/jamasurgery/fullarticle/400927](https://jamanetwork.com/journals/jamasurgery/fullarticle/400927)
CR-POSSUM and Surgical Apgar Score as predictive factors for patients’ allocation after colorectal surgery.
Pinho S et al. • Braz J Anesthesiol (English Edition). 2018;[https://doi.org/10.1016/j.bjane.2018.01.006](https://doi.org/10.1016/j.bjane.2018.01.006)
