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Meta‐analysis of the predictive value of C‐reactive protein for infectious complications in abdominal surgery. BJS 2015; 102: 590-598.

Published: 16th March 2015

Authors: M. Adamina, T. Steffen, I. Tarantino, U. Beutner, B. M. Schmied, R. Warschkow et al.

Background

The aim of this analysis was to assess the predictive value of C‐reactive protein (CRP) for the early detection of postoperative infectious complications after a variety of abdominal operations.

Method

A meta‐analysis of seven cohort studies from a single institution was performed. Laparoscopic gastric bypass and colectomies, as well as open resections of cancer of the colon, rectum, pancreas, stomach and oesophagus, were included. The predictive value of CRP was assessed by the area under the curve (AUC) of the receiver operating characteristic (ROC) curve.

Results

Of 1986 patients, 577 (29·1 (95 per cent c.i. 27·1 to 31·3) per cent) had at least one postoperative infectious complication. Patients undergoing laparoscopic gastric bypass (383 patients) or colectomy (285), and those having open gastric (97) or colorectal (934) resections were combined in a meta‐analysis. Patients who had resection for cancer of the oesophagus (41) or pancreas (246) were analysed separately owing to heterogeneity. CRP levels 4 days after surgery had the highest diagnostic accuracy (AUC 0·76, 95 per cent c.i. 0·73 to 0·78). Sensitivity and specificity were 68·5 (60·6 to 75·5) and 71·6 (66·6 to 76·0) per cent respectively. Positive and negative predictive values were 50·4 (46·0 to 54·8) and 84·3 (80·8 to 87·3) per cent. The threshold CRP varied according to the procedure performed.

Conclusion

The negative predictive value of serum CRP concentration on day 4 after surgery facilitates reliable exclusion of postoperative infectious complications.

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1 Comment

Kirsty McFarlane

3 years ago

Sir,

We read with interest the recent meta-analysis by Adamina et al. on the predictive value of C-reactive protein (CRP) for infective complications following a range of abdominal surgical procedures (1). This meta-analysis of 7 cohort studies from a single institution included laparoscopic and open procedures for both benign and malignant disease. The authors reported that of the 1986 patients included, 29.1% suffered an infective complication. Furthermore, CRP concentrations on day 4 post surgery were reported to have the greatest diagnostic accuracy and the authors conclude that its negative predictive value facilitated reliable exclusion of post-operative infective complications. We have several comments.

Importantly they report that in patients undergoing colonic resection, those having a laparoscopic procedure had a far lower CRP threshold on day 4 (56 mg/L) compared to those having open surgery (123 mg/L). This is contradictory to the recent report of Ramanathan and colleagues that, in patients undergoing potentially curative surgery for colon cancer, although the magnitude of the systemic inflammatory response, evidenced by CRP concentrations, was reduced in those undergoing laparoscopic surgery, the thresholds for predicting the development of infective complications on days 3 and 4 were the same following both laparoscopic and open surgery (2).

This difference is important and needs clarification. It would also be important to explain why these thresholds should be different in laparoscopic and open surgery since a true difference implies that the CRP rise is due to the complication and not the cause of it. In contrast, if the thresholds are the same then it may be that the complication is triggered by the magnitude of the CRP rise. The implications are also important as if the latter is true then increasing the rate of laparoscopic resections may result in a reduced frequency of infective complications.

A potentially confounding factor was that the authors chose to analyse studies involving a wide variety of surgical procedures with presumably a wide variation in infective complication rates. It may have been more clinically relevant to analyse patients undergoing the different procedures separately.

Finally, other systematic reviews have reported the clinical utility of day 3 CRP in predicting infective complications including anastomotic leak following surgery (3). In the present study it was of interest that the positive predictive value of CRP on days 3 and 4 were similar (0.46 vs. 0.45) as was the negative predictive value (0.82 vs. 0.86) yet the authors chose to focus on the day 4 values. Indeed, the use of these markers at an earlier time point would be more clinically useful and allow earlier assessment and management of the developing complication.

David G Watt
Stephen T McSorley
Paul G Horgan
Donald C McMillan

Academic Unit of Surgery
w
Glasgow Royal Infirmary
10-16 Alexandra Parade
Glasgow G31 2ER
UK
mrdgwatt@hotmail.co.uk

References:
1. Adamina M, Steffen T, Tarantino I, Beutner U, Schmied BM, Warschkow R. Meta-analysis of the predictive value of C-reactive protein for infectious complications in abdominal surgery. Br J Surg 2015; E-pub ahead of print: 10.1002/bjs.9756.
2. Ramanathan ML, MacKay G, Platt J, Horgan PG, McMillan DC. The impact of open versus laparoscopic resection for colon cancer on C-reactive protein concentrations as a predictor of postoperative infective complications. Ann Surg Oncol 2015; 22: 938-943.
3. Singh PP, Zeng IS, Srinivasa S, Lemanu DP, Connolly AB, Hill AG. Systematic review and meta-analysis of use of serum C-reactive protein levels to predict anastomotic leak after colorectal surgery. Br J Surg 2014; 101: 339-346.