The Utility of CRP as a decision making tool

Date First Published:
October 28, 2022
Last Updated:
February 21, 2023
Report by:
Daniel Robinson, ED F2 (Lancashire Teaching Hospitals )
Search checked by:
Daniel Robinson, Lancashire Teaching Hospitals
Three-Part Question:
In [ED patients with acute abdominal pain], how useful is [C-Reactive Protein] as a [surgical decision making tool]?
Clinical Scenario:
25 year old Male presenting with a 2 day history of central abdominal pain associated with nausea, vomiting and poor appetite. On examination he is restless with pain, dehydrated and diffusely tender with guarding in his lower abdomen. CRP has not been done on admission bloods, and the specialty team want a CRP done before they will see him.
Search Strategy:
PubMed up to 11/22.
((Acute Abdomen) OR (Abdominal Pain) OR (Surgical Abdomen)) AND ((CRP) OR (C Reactive Protein))AND ((Prognosis) OR (Diagnosis) OR (Projection) OR (Outcome) OR (Operation) OR (Surgery) OR (Surgical Operation) OR (Surgical Intervention))
Search Details:
Medical Dictionary and Thesaurus used to Generate Search Terms. Search results were limited to the last 5 years to manage research load, and to include papers with the most recent evidence. Further clarifications, additions or synonyms within the search terms did not yield any additional articles.
Outcome:
1618 papers from the entire search. This was narrowed to 643 abstracts when results were filtered to only include those from the last 5 years.
Relevant Paper(s):
Study Title Patient Group Study type (level of evidence) Outcomes Key results Study Weaknesses
Do serum acute phase reactants predict clinical outcome in emergency general surgical admissions? Saad Ullah Khan 24/06/2018 United Kingdom 9738 patients admitted under General Surgery (5534 via ED) with a presenting complaint abdominal pain over a 2 year period Retrospective observational multicentre study Use of Diagnostic Imaging Raised CRP found to be significant predictor (p = 0.0001) As this was retrospective, no blinding pf randomisation was possible. The method of analysis was also not well demonstrated or explained.
Surgical Intervention Raised CRP found to be significant predictor (p = 0.0001), and >150 - 3x more likely
ITU Admission Raised CRP found to be significant predictor, and >150 - 7x more likely
Conservative Management of Complicated Colonic Diverticulitis in Early and Late Elderly Gennaro Perrone 24/02/2021 Italy 71 Elderly (65+) Patients with complicated acute Left sided Diverticulitis Retrospective single centre population study Recurrence (65-74yo) CRP 138.37 (16.8 - 250) All patients were also for conservative management, but the study did not explain why patients were selected for conservative over operative management, nor CRPs role in this decision. The only relationship detailed was that of CRP and recurrence.
Recurrence (75yo+) CRP 125.5 (9 - 250)
Non Recurrence (65-74yo) CRP 87.86 (6.8 - 237.9)
Non Recurrence (75+yo) CRP 75.5 (16.1 - 106)
Prediction of surgical management for operated adhesive postoperative small bowel obstruction in a pediatric population Yuhua Deng et Al 01/03/2019 China 712 Patients with acute small bowel obstruction (Criteria = Attending surgeon assigning diagnosis, or abdominal pain, vomiting and complete constipation) Retrospective Analysis Conservative Management CRP 11.6 (+/- 3.8) While CRP is noted as being very similar between the two groups, there is no mention whether or not that it played a role in decision making. This was only documented as having been decided based on clinical course or imaging findings.
Operative Management CRP 12.2 (+3.7)
Efficacy of scheduled return visits for emergency department patients with non-specific abdominal pain Annemieke E Boendermaker et Al. 02/06/2018 Netherlands 305 ED Patients diagnosed with non-specific abdominal pain, discharged and reviewed within 30 hours. A patient was deemed to have had a clinically relevant change in treatment resulting from re-evaluation at >30hours if the diagnosis and treatment plan were changed from the index visit. This included review by a senior clinician and further bloods (Including CRP) Single Centre Retrospective Cohort Study Change in Diagnosis/Treatment Radiological studies at re-evaluation visit had an adjusted R2 0.329, OR 13.3 (5.8 - 30.6), p <0.01 Vital signs and laboratory studies were not always performed in patients with abdominal pain, meaning they were not available to researchers, reducing the population studied. It should also be noted that change in diagnosis and treatment at follow up is vulnerable to confirmation and interpretation bias. There was no mention of the relation of the reviewing doctor compared to the index visit doctor, or how this was mitigated.
Increase in CRP between visits was a significant predictor
Elevated CRP at index assisted in identifying those with increased likelihood of Rx at follow up.
Radiologic predictors for failure of non-operative management of complicated diverticulitis: a single-centre cohort study Stefan Reischl et Al. 141 with Hinchey Ib - II Acute Diverticulitis Single centre Retrospective Cohort Study Resection within 30 days CRP was higher in those operated within 30 days. It was also associated witn CT findings of an abcess >1cm, which was a predictor of surgery within 30days.
Clinical prediction of complicated appendicitis: A case-control study utilizing logistic regression Yosuke Sasaki et Al. 06/06/2020 Japan Patients diagnosed with Acute Appendicitis on US/CT, and who had any form of management. 236 patients in total.
198 Uncomplicated Appendictis
38 Complicated Appendicitis
Single centre retrospective case-control study Complicated CA CRP higher in complicated vs uncomplicated appendicitis, and was the only predictive factor or logaristic regression While there is a link between higher CRPs and the likelihood of more severe disease and then operative management, the decision making process for surgery was not discussed. As this was retrospective in nature, the operating surgeons could not be asked why they had made this decision.
Treated with Appendicectomy 31.6% of complicated appendicitis patients were managed with appendicectomy compared to 11.1% of those with uncomplicated disease.
Author Commentary:
Very early on in Research it became apparent that CRP is a very good diagnostic tool for Appendicitis, and should be a part of the Alvarado Criteria.

CRP often, but not always correlates with more severe radiological findings, which in turn makes surgical intervention more likely. However, CRP alone was never documented as being used as a surrogate for imaging even if it did predict more severe imaging findings.

The rationale behind decision making was very infrequently discussed, and could only be inferred it was based on radiological findings rather than CRP. Rationales for surgery appeared to be
otImaging – Normally booked/requested by the surgical team
otClinical deterioration and unwellness
Bottom Line:
For non-inflammatory surgical conditions, CRP is not useful in decision making. For inflammatory conditions, CRP can be useful in decision making, but it would appear that radiological findings are more so. Therefore, it would appear that in patients with acute abdominal pain in ED, the utility of CRP depends on the most likely diagnosis.
References:
  1. Saad Ullah Khan. Do serum acute phase reactants predict clinical outcome in emergency general surgical admissions?
  2. Gennaro Perrone. Conservative Management of Complicated Colonic Diverticulitis in Early and Late Elderly
  3. Yuhua Deng et Al . Prediction of surgical management for operated adhesive postoperative small bowel obstruction in a pediatric population
  4. Annemieke E Boendermaker et Al. . Efficacy of scheduled return visits for emergency department patients with non-specific abdominal pain
  5. Stefan Reischl et Al.. Radiologic predictors for failure of non-operative management of complicated diverticulitis: a single-centre cohort study
  6. Yosuke Sasaki et Al.. Clinical prediction of complicated appendicitis: A case-control study utilizing logistic regression