POSSUM, Other Scoring Systems Unable to Estimate Perioperative Complications in CRC

Scoring systems meant to predict complications of resection surgery to treat colorectal cancer (CRC), such as the Physiological and Operative Severity Score for the enumeration of Mortality and Morbidity (POSSUM), have been found to be less accurate in the present day, according to a study published in the Journal of Clinical Medicine. Revisions of these scoring systems could increase accuracy.

Scoring systems that measure variability in health and disease, as well as the risk of morbidity and mortality, have become more plentiful in recent years. POSSUM was created in 1991 to measure the surgical severity score and the physiological score of a patient to make an informed decision on whether to undergo a surgery, given the potential risks. The colorectal POSSUM test (CR-POSSUM) was created to counteract the underestimation of mortality of colorectal surgeries in emergencies and in patients aged 80 years and older whereas the Portsmouth-POSSUM (P-POSSUM) test was created for a more accurate estimation of perioperative mortality. The significance of the POSSUM, CR-POSSUM, and P-POSSUM tests were evaluated in this study.

Colon cancer | Image credit: Crystal light - stock.adobe.com

The study focused on patients who had surgery for CRC in 2 tertiary centers in Germany from 2002 to 2009 and 2012 to 2019. Operative severity scores and physiological scores were collected for each patient according to the POSSUM, P-POSSUM, and CR-POSSUM scoring. Calculations were made according to the original publications that they were created in.

There were 485 patients who were included in the study, of which overall in-hospital morbidity affected 47.6% with 447 complications. Postoperative complications were not found to be affected by the age of the patient whereas male patients and patients who were treated for rectal cancer had more complications; patients with laparoscopic surgery had less complications.

The mean (SD) morbidity calculated by POSSUM was 55.33% (0.235), which was significantly higher than the actual morbidity. POSSUM predicted that the probability of male patients having postoperative complications was 57.33% (0.239) compared with the female patients who had a predicted probability of 52% (0.225). Patients aged 60 years and younger had a predicted complication rate of 44.79% (0.241) compared with 51.57% (0.231) in patients aged 61 to 70 years, and 64.14% in patients aged 71 years and older.

Patients with rectal cancer had a higher predicted morbidity of 59.88% (0.232) compared with a predicted complication rate of 52.02% (0.232) in patients with colon cancer. Postoperative complications were also predicted to be lower in patients who had laparoscopic surgery (49.52% [0.219]) compared with open-approach (58.05% [0.238]). POSSUM was able to identify patients with anastomotic leakage or septicemia and those requiring a second operation as particular indicators of morbidity.

The actual mortality rate in the hospital was 2.06%, which was significantly lower than the POSSUM predicted rate of 17.54% (0.160). P-POSSUM had a predicted mortality of 7.39% (0.116) whereas CR-POSSUM predicted a rate of 6.98% (0.083), although the P-POSSUM scores were not significantly different when separated into groups of patients with colon cancer and patients with rectal cancer.

There were some limitations to this study. The increasing adoption of laparoscopic surgeries, enhanced recoveries, and improvements in stapling could have played an influencing factor in the long observation period. Hospital mortality and 30-day mortality may not align due to the average hospital length being 16 days. The generalizability of this study may be limited due to the study taking place at 2 centers in Germany.

Although the POSSUM score was able to determine factors that would increase morbidity, the scores should not be taken into account when counseling patients due to the lack of variables until after an intervention has been performed. The researchers suggest that a new tool that is more reliable and precise should be created in the near future.

Reference

Bürtin F, Ludwig T, Leuchter M, Hendricks A, Schafmayer C, Philipp M. More than 30 years of POSSUM: are scoring systems still relevant today for colorectal surgery? J Clin Med. 2024;13:173. doi:10.3390/jcm13010173