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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))
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.

Search 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)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Saad Ullah Khan et Al. 24/06/18 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
Gennaro Perrone 24/02/21 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)
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)
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.
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.
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.

Comment(s)

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 o Imaging – Normally booked/requested by the surgical team o Clinical deterioration and unwellness

Clinical 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? J Ayub Med Coll Abbottabad 2018 Jul-Sep;30(3):337-341.
2. Gennaro Perrone Conservative Management of Complicated Colonic Diverticulitis in Early and Late Elderly Medicina (Kaunas). 2022 Jan; 58(1): 29.
3. Yuhua Deng et Al Prediction of surgical management for operated adhesive postoperative small bowel obstruction in a pediatric population Medicine (Baltimore) . 2019 Mar;98(11):e14919
4. Annemieke E Boendermaker et Al. Efficacy of scheduled return visits for emergency department patients with non-specific abdominal pain Emerg Med J . 2018 Aug;35(8):499-506.
5. Stefan Reischl et Al. Radiologic predictors for failure of non-operative management of complicated diverticulitis: a single-centre cohort study Langenbecks Arch Surg . 2021 Nov;406(7):2409-2418.
6. Yosuke Sasaki et Al. Clinical prediction of complicated appendicitis: A case-control study utilizing logistic regression World J Clin Cases. 2020 Jun 6; 8(11): 2127–2136.