Outcomes following Colorectal Surgery: A Comparative Study of CR –POSSUM and ACS – NSQIP Risk Calculator

Nitin Vashistha, MS, FACS¹, Arati Verma, MBBS, DHHM, PGDMLS², Dinesh Singhal, MS, FACS, DNB, Surgical Gastroenterology¹. ¹Department of Surgical Gastroenterology, Max Super Speciality Hospital, Delhi, India, ²Department of Medical Quality, Max Super Speciality Hospital, Delhi, India

Background: Several studies have reported outcomes of colorectal surgery (CRS) based either on CR – POSSUM or ACS – NSQIP risk calculator. To the best of our knowledge, no study to date has evaluated / compared outcomes of the two risk calculators on same patient cohort .

We report outcomes of elective and emergency CRS by CR – POSSUM and ACS – NSQIP risk calculator.

Patients and Methods: This is a single center observational study of 86 consecutive adult (≥ 18 years) patients who underwent elective or emergency, resective &/or reconstructive CRS from March 2013 to March 2018. Procedures such as appendicectomy, diverting colostomy, laparoscopic rectopexy were excluded from analysis.

Data was accessed from institutional electronic health record system. The CR – POSSUM and ACS – NSQIP scores for each patient was calculated. Actual outcomes were then compared with those predicted by risk calculators.

Results: Of the 86 patients (60 Indians and 26 International) there were 56 males and 30 females with a mean age of 57 (range 18-93) years. Of these 59 (68.6%) underwent elective whereas 27(31.4%) had emergency CRS. Sixty two (72%) and 24 (38%) patients underwent open and minimally invasive procedures (laparoscopic -21 and robotic -3) respectively. The median length of stay was 08 (range 02-40) days. The mortality following elective and emergency operations was 1/59 (1.6%) and 8/27(29.6%) respectively.

By CR- POSSUM, ratio of observed to expected mortality was 1.29 with no significant difference between the two values.

Objective comparison between overall actual outcomes and those predicted by ACS – NSQIP risk calculator revealed no significant difference in any of the parameters studied (Figure 1).

A comparison of actual and predicted ACS – NSQIP outcomes in elective and emergency CRS is provided in Table 1. The score significantly underestimated SSI and over predicted the length of stay following emergency CRS.

Conclusions: Both CR – POSSUM and ACS – NSQIP risk calculator accurately predicted mortality in our cohort of CRS patients. CR – POSSUM provides information on single domain of mortality only and requires operative findings to calculate the score and is therefore more useful for surgical audits. In comparison ACS – NSQIP risk calculator provides comprehensive information prior to surgical intervention that may be useful for both individual prognostication as well as surgical audits.

Figure 1: Actual versus predicted outcomes by ACS-NSQIP risk calculator