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Diagnostic utility of fecal calprotectin in patients presenting to the emergency department with suspected acute appendicitis
American Journal of Emergency Medicine xxx (xxxx) xxx
Contents lists available at ScienceDirect
American Journal of Emergency Medicine journal homepage: www.elsevier.com/locate/ajem
Diagnostic utility of fecal calprotectin in patients presenting to the emergency department with suspected acute appendicitis Wenqing Zhou a,1, Huiying Qiao b,1, Weiguo Yuan a, Zhibing Yao a, Kai Liu a, Jun Wang a, Yongkui Pang a,⇑ a b
Department of General Surgery, The Fifth Pepple’s Hospital of Wujiang Area, Suzhou, Jiangsu, People’s Republic of China Department of General Practice, Suzhou Ninth Pepple’s Hospital, Suzhou, Jiangsu, People’s Republic of China
a r t i c l e
i n f o
Article history: Received 1 September 2019 Received in revised form 6 October 2019 Accepted 17 October 2019 Available online xxxx Keywords: Acute appendicitis Fecal calprotectin Negative appendectomy Diagnosis Biomarker
a b s t r a c t Background: Acute appendicitis (AA) is one of the most common diseases faced by the surgeon in the emergency department. In clinical practice, how to diagnose patients with AA accurately is still challenging. Methods: We conducted a prospective study of 84 patients who presented in the emergency department with suspected AA and measured fecal calprotectin (FC) value. The final diagnosis of AA was independently determined without reference to the test results of FC. Then, we retrospectively analyzed the FC value for identifying AA. Results: FC value in patients with AA were significantly higher than that in patients without AA (240.5 vs. 68.5 ug/g, P < 0.001). Receiver-operating characteristic analyses demonstrated FC value to be highly sensitive and specific for the diagnosis of AA, as indicated by an overall area under the curve (AUC) of 0.928 (500 times of boot strap estimated 95% CI, 0.855–0.972), with an optimal cut off point of 106 ug/g. FC levels in 26 patients with simple AA were significantly lower than it in the 14 patients with suppurative AA (206 vs. 304ug/g, P = 0.001). Conclusions: FC test provides a sensitive, convenient and economical method to help facilitate the diagnosis of AA in emergency department. Especially for hospitals without computed tomography equipment or patients who are not suitable to exposed to radiation, FC test is of great significance for improving the diagnostic accuracy of AA. Ó 2019 Published by Elsevier Inc.
1. Introduction Acute appendicitis (AA) is one of the most common diseases faced by the surgeon in the emergency department [1]. The principle of treatment for this disease is to make early diagnosis and timely surgical intervention. In clinical practice, many surgeons adopt aggressive treatment strategies to avoid the incidence of severely complications associated with perforation (even mortality) [2]. Historically, the rate of negative appendectomy is alarming, reaching 15% in the general population and even 40% in
Abbreviations: AA, acute appendicitis; FC, fecal calprotectin; AUC, area under the curve; CT, computed tomography; OTV, onset to visit; WBC, white blood cell count; CRP, C-reactive protein; ALT, alanine aminotransferase; IBD, inflammatory bowel disease. ⇑ Corresponding author at: Department of General Surgery, The Fifth Pepple’s Hospital of Wujiang Area, 555 Xinyou Road, Wujiang District, Suzhou, Jiangsu 215211, People’s Republic of China. E-mail address: [email protected] (Y. Pang). 1 Wenqing Zhou and Huiying Qiao contributed equally to this work.
women of reproductive age [3,4]. The main reason for this unsatisfactory outcome is that various pathologies in the abdomen can appear similar to the signs and symptoms of AA [5]. Nowadays, how to diagnose patients with AA more accurately is still challenging. In the past two decades, it has been reported that computed tomography (CT) can increase the specificity of diagnostic evaluation and reduces the rate of negative appendectomy [6]. However, CT has disadvantages that include the potential for inaccurate interpretation, exposure to radiation, and delay in definitive treatment for AA [7]. More importantly, equipment and qualified personnel for CT is not available universally in all hospitals, especially in emergency department of primary hospitals. Given these drawbacks, sensitive, economical and accurate markers that can help in the preoperative screening of patients with suspected AA are thus mandatory. Calprotectin is a 36.5 kDa calcium- and zinc-binding heterodimer that has been found as the major cytosolic protein in neutrophil granulocytes [8]. In previous studies, fecal calprotectin
https://doi.org/10.1016/j.ajem.2019.10.022 0735-6757/Ó 2019 Published by Elsevier Inc.
Please cite this article as: W. Zhou, H. Qiao, W. Yuan et al., Diagnostic utility of fecal calprotectin in patients presenting to the emergency department with suspected acute appendicitis, American Journal of Emergency Medicine, https://doi.org/10.1016/j.ajem.2019.10.022
2
W. Zhou et al. / American Journal of Emergency Medicine xxx (xxxx) xxx
(FC) has been mainly proposed as a marker for the diagnosis and follow-up of many bowel pathologies [8,9]. Recently, high calprotectin activity was confirmed within the lumen of vermiform appendix specimens following appendectomy for AA [9]. Here, we postulated that changes of the calprotectin expression can be transferred to the colonic lumen by inflammatory cells, making FC potentially useful for diagnosing patients with suspected AA.
Receiver-operating characteristic (ROC) curves were performed to evaluate the utility of FC value for the diagnosis of AA. In addition, optimal cut-point of FC value for identifying or excluding risk of AA were identified. These analyses were performed with R soft-
2. Methods
Total 84 eligible patients were enrolled in the current study. Among these patients, 2 patients underwent negative appendectomy. In addition, 3 patients with AA were initially misdiagnosed until further close observation. Finally, total of 40 (35%) patients had the diagnosis of AA, and the remaining 44 (59%) did not have AA at this emergency room visit. Comparisons of clinical characteristics between these two groups are presented in Table 1. No statistically significant difference was determined between the groups in terms of age, sex, onset to visit (OTV) interval and the ratio of pregnant patients. In addition, the symptoms represent the ‘‘classic” presentation of AA, such as nausea, vomiting and fever, were also occupied similar proportion in the no AA group (all of P < 0.05). As expected, WBC count, CRP value, and FC value in AA group were found to be higher than in no AA group. The relationship between preoperative FC value and the risk of AA was showed in Fig. 2. ROC analyses demonstrated FC value to be highly sensitive and specific for the diagnosis of AA, as indicated by an overall AUC of 0.928 (500 times of boot strap estimated 95% CI, 0.855–0.972), with an optimal cut point of 106 ug/g, which was sensitive and specific for ruling in the diagnosis of AA. Postoperative pathological specimens of 40 patients with appendicitis were retrospectively reviewed. Overall, we recorded a significant positive correlation between FC value and the severity of AA. FC levels in 26 patients with simple AA were significantly lower than it in the remaining 14 patients with suppurative AA (206 vs. 304ug/g, P = 0.001, Fig. 3).
2.1. Ethics The study was conducted in accordance with the ethical principles of the Declaration of Helsinki and the principles of Good Clinical Practice. The institutional review board of the Wujiang District Fifth People’s Hospital approved all investigational procedures involved in this study. A written consent was obtained from all patients before taking the specimen and patient data was anonymous prior to analysis. 2.2. Study population. The current study population was drawn from consenting adult patients (age 18 years) who presented to the emergency department of the Wujiang District Fifth People’s Hospital and with a complaint of abdominal pain in the year of 2018. Exclusion criteria for the study were previous history of abdominal disease; gastrointestinal diseases or using non-steroidal anti-inflammatories or proton pump inhibitors; inflammatory bowel disease; abdominal pain for more than 72 h; patients who have received anti-inflammatory treatment and those who could not provide stool specimens. 2.3. Data collection Clinical characteristics of each patient were recorded in detail, including demographics, symptoms, signs, medical history, medication use, and any imaging tests in the emergency department including ultrasound and CT. The diagnosis process for patients with abdominal pain in our hospital was showed in Fig. 1. Patients with suspected AA received laparoscopic appendectomy under general anesthesia. The entire perioperative treatment process is basically the same as described in previous article [10]. 2.4. Determination of diagnosis: A week follow-up was performed on every patient to determine any clinical events occurred during the period and whether there is a misdiagnosis. Follow up results and the pathological test results of the surgical specimen determined the final diagnosis. 2.5. FC analysis FC testing was performed with a commercially available diagnostic Kit (Coloidal Gold) for Calprotectin (Xiamen Wiz Biotech co. LTD, China) according to established methods. We measured FC value at the time of patient visits and glycerin suppository is used if necessary. 2.6. Statistical analysis: Comparisons of clinical characteristics between patients who had AA and those who did not were performed with chi-square tests for categorical data and student t tests for continuous data. A two-sided p value of <0.05 was considered significant.
ware (version 3.40, http://www.R-project.org). 3. Results
4. Discussion Despite being a common disease, the absence of reliable discriminators for the diagnosis of AA still exists. In the current study, we demonstrated that FC would be an effective predictor of AA. Therefore, the combination of FC value plus standard clinical assessment should be promoted to reduce the number of patients with negative appendectomy and misdiagnosis. Previous studies regarding FC have largely focused on the gastrointestinal disorders, especially inflammatory bowel disease (IBD). It has an established role as a diagnostic modality and a biomarker of disease activity in patients with IBD, with high sensitivity and specificity [11–13]. Theoretically, FC is secreted by activated macrophages and neutrophils and acts by inducing leukocyte recruitment and the secretion of pro-inflammatory cytokines [14]. Therefore, the concentration of FC reflects the extent of neutrophil migration to the gastrointestinal tract [15]. During the procession of AA, an inflammation of the appendix is significantly associated with changes in the expression of calprotectin [16]. The inflammatory cells then transferred from the lumen of the vermiform appendix into the colonic lumen, causing calprotectin from such cells being detectable in feces [17]. It is thus logically explained the results found in the current study that patients with AA have significant higher FC levels. Pathological specimen from AA patients showed the degree of infiltration of inflammatory cells is positively correlated with FC value. This also indirectly suggested the hypothesis as we discussed above. In adult patients, CT has also been widely used to diagnose AA, but there are shortcomings such as radiation, high cost and inconvenience [2]. Our results provide another simple, cheap and conve-
Please cite this article as: W. Zhou, H. Qiao, W. Yuan et al., Diagnostic utility of fecal calprotectin in patients presenting to the emergency department with suspected acute appendicitis, American Journal of Emergency Medicine, https://doi.org/10.1016/j.ajem.2019.10.022
W. Zhou et al. / American Journal of Emergency Medicine xxx (xxxx) xxx
3
Fig. 1. General approach to the patient with suspected acute appendicitis in the emergency department.
Table 1 Clinical characteristics of patients who had abdomen pain with or without AA.
FC (lg/g) WBC (10–9/ml) CRP (mg/dL) Age (years) Sex (female,%) OTV interval (hours) Pregent (%) Nausea/vomiting (%) Fever (%) ALT > 40 (%) Imaging positive (%)
No AA
AA
(N = 44) 68.5 (44.0) 10.1(4.4) 17.2 (14.7) 46 (17) 23 (52.3) 32 (21) 11 (25.0) 31 (70.5) 14 (31.8) 13 (29.5) 2 (4.5)
(N = 40) 240.5 (94.5) 17.6 (7.0) 33.7 (18.8) 49 (17) 19 (47.5) 31 (20) 6 (15.00) 28 (70.0) 19 (47.5) 11 (27.5) 37 (92.5)
P-value <0.001* <0.001* <0.001* 0. 466 0. 662 0.782 0.255 0.964 0.142 0.836 <0.001*
Significant difference. Abbreviations: AA, acute appendicitis; FC, fecal calprotectin; WBC, white blood cell count; CRP, C-reactive protein; OTV, onset to visit; ALT, alanine aminotransferase.
nient alternative that achieves the similar accuracy. This is especially important not only for hospitals that cannot provide CT examinations but also for those patients who are not suitable to exposed to radiation, such as pregnant women. Currently, diagno-
sis of AA can be particularly challenging during pregnancy because of the overlapping of symptoms between appendicitis and pregnancy [18]. In a study of 94,489 patients, appendectomy for perforated appendicitis resulted in up to 6% fetal loss and 11% early delivery; for negative appendectomy, the fetal loss rate and early delivery rate were 4% and 10%, respectively [19]. Therefore, FC measurement is to be expected to improve this status in the future. In clinical practice, the greatest obstacle to applicate FC may be the potential difficulty and time delay in obtaining stool specimens from emergency department patients. Actually, previous studies showed that calprotectin is resistant to proteolytic degradation and can be stable for up to 7 days in stool samples at room temperature [20]. A sample of less than 5 g is sufficient for reliable measurements [20]. In addition, a number of commercial assays are available for simple and rapid measurement of calprotectin [21,22]. These qualities open up room for a quick analysis in the emergency department without waste of time, such as collect fecal samples at home or obtain small amount of specimens by glycerin suppository. Therefore, further research projects relevant to every step of the specimen collection should be promoted to modernize and standardize the diagnosis of AA. Two main limitations in this study must be mentioned. First, it occurred in a single center and only include the small number of
Please cite this article as: W. Zhou, H. Qiao, W. Yuan et al., Diagnostic utility of fecal calprotectin in patients presenting to the emergency department with suspected acute appendicitis, American Journal of Emergency Medicine, https://doi.org/10.1016/j.ajem.2019.10.022
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W. Zhou et al. / American Journal of Emergency Medicine xxx (xxxx) xxx
Funding This work was supported by the Science and Education Foundation of Wujiang district (wwk201725). Declaration of Competing Interest Authors reported no conflict of interest. References
Fig. 2. The relationship between fecal calprotectin value and the risk of acute appendicitis. Fecal calprotectin was highly sensitive and specific for the diagnosis of acute appendicitis, with a highly significant area under the curve of 0.928 (95% CI, 0.855–0.972). The blue shading shows the 500 times of bootstrap estimated 95% CI with the area under the curve. The cut off points of 106 ug/g was optimal in the current study.
Fig. 3. FC levels in patients with simple acute appendicitis and patients with suppurative acute appendicitis. The mean fecal calprotectin was 206 lg/g in 26 patients with simple appendicitis acute appendicitis; The mean fecal calprotectin was 304 lg/g in the remaining 14 patients with suppurative acute appendicitis patients (206 vs.304 lg/g, P = 0.001).
patients with AA. Thus, whether the present findings apply to other regions with different prevalence of AA and patients with different clinical characteristics still need verified by larger multicenter cohorts. Second, although our study found the cutoff value of FC to about 100 ug /g (109 ug / g) strongly suggests the high risk of AA. It is of note that there are quantitative differences between the available FC commercial assays today [23,24]. Therefore, this cut-off values may not be suitable for other assays.
5. Conclusion In conclusion, the evidence overall suggests that FC can be a helpful biomarker for identifying AA. When examining patients for clinically suspected AA, FC test provides a sensitive, convenient and economical method to help facilitate the diagnosis. More timely and accurate diagnosis will help reduce the risks of perforation or unnecessary operation thus improve overall outcomes.
[1] Gwynn LK. The diagnosis of acute appendicitis: clinical assessment versus computed tomography evaluation. J Emerg Med 2001;21(2):119–23. [2] Bhangu A, Soreide K, Di Saverio S, Assarsson JH, Drake FT. Acute appendicitis: modern understanding of pathogenesis, diagnosis, and management. Lancet 2015;386(10000):1278–87. https://doi.org/10.1016/s0140-6736(15)00275-5. [3] Flum DR, Morris A, Koepsell T, Dellinger EP. Has misdiagnosis of appendicitis decreased over time? A population-based analysis. Jama 2001;286 (14):1748–53. https://doi.org/10.1001/jama.286.14.1748. [4] Wagner PL, Eachempati SR, Soe K, Pieracci FM, Shou J, Barie PS. Defining the current negative appendectomy rate: for whom is preoperative computed tomography making an impact?. Surgery 2008;144(2):276–82. https://doi.org/ 10.1016/j.surg.2008.03.040. [5] Garcia EM, Camacho MA, Karolyi DR, Kim DH, Cash BD, Chang KJ, et al. ACR appropriateness criteria((R)) right lower quadrant pain-suspected appendicitis. J Am Coll Radiol 2018;15(11s):S373–87. https://doi.org/ 10.1016/j.jacr.2018.09.033. [6] Shogilev DJ, Duus N, Odom SR, Shapiro NI. Diagnosing appendicitis: evidencebased review of the diagnostic approach in 2014. Western J Emerg Med 2014;15(7):859–71. https://doi.org/10.5811/westjem.2014.9.21568. [7] Yu CW, Juan LI, Wu MH, Shen CJ, Wu JY, Lee CC. Systematic review and metaanalysis of the diagnostic accuracy of procalcitonin, C-reactive protein and white blood cell count for suspected acute appendicitis. Br J Surg 2013;100 (3):322–9. https://doi.org/10.1002/bjs.9008. [8] Ricciuto A, Griffiths AM. Clinical value of fecal calprotectin. Crit Rev Clin Lab Sci 2019;56(5):307–20. https://doi.org/10.1080/10408363.2019.1619159. [9] Manceau H, Chicha-Cattoir V, Puy H, Peoc’h K. Fecal calprotectin in inflammatory bowel diseases: update and perspectives. Clin Chem Lab Med 2017;55(4):474–83. https://doi.org/10.1515/cclm-2016-0522. [10] Sabbagh C, Masseline L, Grelpois G, Ntouba A, Dembinski J, Regimbeau JM. Management of uncomplicated acute appendicitis as day case surgery: can outcomes of a prospective study be reproduced in real life?. J Am Coll Surg 2019;229(3):277–85. https://doi.org/10.1016/j.jamcollsurg.2019.04.031. [11] Kopylov U, Yung DE, Engel T, Avni T, Battat R, Ben-Horin S, et al. Fecal calprotectin for the prediction of small-bowel Crohn’s disease by capsule endoscopy: a systematic review and meta-analysis. Eur J Gastroenterol Hepatol 2016;28(10):1137–44. https://doi.org/10.1097/ meg.0000000000000692. [12] Henderson P, Anderson NH, Wilson DC. The diagnostic accuracy of fecal calprotectin during the investigation of suspected pediatric inflammatory bowel disease: a systematic review and meta-analysis. Am J Gastroenterol 2014;109(5):637–45. https://doi.org/10.1038/ajg.2013.131. [13] van Rheenen PF, Van de Vijver E, Fidler V. Faecal calprotectin for screening of patients with suspected inflammatory bowel disease: diagnostic metaanalysis. BMJ 2010;341:. https://doi.org/10.1136/bmj.c3369c3369. [14] Metafuni E, Giammarco S, De Ritis DG, Rossi M, De Michele T, Zuppi C, et al. Fecal but not serum calprotectin is a potential marker of GVHD after stem cell transplantation. Ann Hematol 2017;96(6):929–33. https://doi.org/10.1007/ s00277-017-2974-1. [15] Schoepfer AM, Beglinger C, Straumann A, Safroneeva E, Romero Y, Armstrong D, et al. Fecal calprotectin more accurately reflects endoscopic activity of ulcerative colitis than the Lichtiger Index, C-reactive protein, platelets, hemoglobin, and blood leukocytes. Inflamm Bowel Dis 2013;19(2):332–41. https://doi.org/10.1097/MIB.0b013e3182810066. [16] Ambe PC, Godde D, Bonicke L, Papadakis M, Storkel S, Zirngibl H. Calprotectin could be a potential biomarker for acute appendicitis. J Transl Med 2016;14 (1):107. https://doi.org/10.1186/s12967-016-0863-3. [17] Ambe PC, Orth V, Godde D, Zirngibl H. Improving the preoperative diagnostic accuracy of acute appendicitis. Can fecal calprotectin be helpful?. PLoS ONE 2016;11(12):. https://doi.org/10.1371/journal.pone.0168769e0168769. [18] Schwulst SJ, Son M. Diagnostic imaging in pregnant patients with suspected appendicitis. JAMA 2019. https://doi.org/10.1001/jama.2019.9164. [19] McGory ML, Zingmond DS, Tillou A, Hiatt JR, Ko CY, Cryer HM. Negative appendectomy in pregnant women is associated with a substantial risk of fetal loss. J Am Coll Surg 2007;205(4):534–40. https://doi.org/10.1016/ j.jamcollsurg.2007.05.025. [20] Roseth AG, Fagerhol MK, Aadland E, Schjonsby H. Assessment of the neutrophil dominating protein calprotectin in feces. A methodologic study. Scand J Gastroenterol 1992;27(9):793–8. https://doi.org/10.3109/ 00365529209011186. [21] Ayling RM, Kok K. Fecal calprotectin. Adv Clin Chem 2018;87:161–90. https:// doi.org/10.1016/bs.acc.2018.07.005.
Please cite this article as: W. Zhou, H. Qiao, W. Yuan et al., Diagnostic utility of fecal calprotectin in patients presenting to the emergency department with suspected acute appendicitis, American Journal of Emergency Medicine, https://doi.org/10.1016/j.ajem.2019.10.022
W. Zhou et al. / American Journal of Emergency Medicine xxx (xxxx) xxx [22] Bello C, Roseth A, Guardiola J, Reenaers C, Ruiz-Cerulla A, Van Kemseke C, et al. Usability of a home-based test for the measurement of fecal calprotectin in asymptomatic IBD patients. Digestive Liver Dis 2017;49(9):991–6. https://doi. org/10.1016/j.dld.2017.05.009. [23] Whitehead SJ, French J, Brookes MJ, Ford C, Gama R. Between-assay variability of faecal calprotectin enzyme-linked immunosorbent assay kits. Ann Clin Biochem 2013;50(1):53–61. https://doi.org/10.1258/acb.2012.011272.
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[24] Oyaert M, Boel A, Jacobs J, Van den Bremt S, De Sloovere M, Vanpoucke H, et al. Analytical performance and diagnostic accuracy of six different faecal calprotectin assays in inflammatory bowel disease. Clin Chem Lab Med 2017;55(10):1564–73. https://doi.org/10.1515/cclm-2016-1012.
Please cite this article as: W. Zhou, H. Qiao, W. Yuan et al., Diagnostic utility of fecal calprotectin in patients presenting to the emergency department with suspected acute appendicitis, American Journal of Emergency Medicine, https://doi.org/10.1016/j.ajem.2019.10.022
Contents lists available at ScienceDirect
American Journal of Emergency Medicine journal homepage: www.elsevier.com/locate/ajem
Diagnostic utility of fecal calprotectin in patients presenting to the emergency department with suspected acute appendicitis Wenqing Zhou a,1, Huiying Qiao b,1, Weiguo Yuan a, Zhibing Yao a, Kai Liu a, Jun Wang a, Yongkui Pang a,⇑ a b
Department of General Surgery, The Fifth Pepple’s Hospital of Wujiang Area, Suzhou, Jiangsu, People’s Republic of China Department of General Practice, Suzhou Ninth Pepple’s Hospital, Suzhou, Jiangsu, People’s Republic of China
a r t i c l e
i n f o
Article history: Received 1 September 2019 Received in revised form 6 October 2019 Accepted 17 October 2019 Available online xxxx Keywords: Acute appendicitis Fecal calprotectin Negative appendectomy Diagnosis Biomarker
a b s t r a c t Background: Acute appendicitis (AA) is one of the most common diseases faced by the surgeon in the emergency department. In clinical practice, how to diagnose patients with AA accurately is still challenging. Methods: We conducted a prospective study of 84 patients who presented in the emergency department with suspected AA and measured fecal calprotectin (FC) value. The final diagnosis of AA was independently determined without reference to the test results of FC. Then, we retrospectively analyzed the FC value for identifying AA. Results: FC value in patients with AA were significantly higher than that in patients without AA (240.5 vs. 68.5 ug/g, P < 0.001). Receiver-operating characteristic analyses demonstrated FC value to be highly sensitive and specific for the diagnosis of AA, as indicated by an overall area under the curve (AUC) of 0.928 (500 times of boot strap estimated 95% CI, 0.855–0.972), with an optimal cut off point of 106 ug/g. FC levels in 26 patients with simple AA were significantly lower than it in the 14 patients with suppurative AA (206 vs. 304ug/g, P = 0.001). Conclusions: FC test provides a sensitive, convenient and economical method to help facilitate the diagnosis of AA in emergency department. Especially for hospitals without computed tomography equipment or patients who are not suitable to exposed to radiation, FC test is of great significance for improving the diagnostic accuracy of AA. Ó 2019 Published by Elsevier Inc.
1. Introduction Acute appendicitis (AA) is one of the most common diseases faced by the surgeon in the emergency department [1]. The principle of treatment for this disease is to make early diagnosis and timely surgical intervention. In clinical practice, many surgeons adopt aggressive treatment strategies to avoid the incidence of severely complications associated with perforation (even mortality) [2]. Historically, the rate of negative appendectomy is alarming, reaching 15% in the general population and even 40% in
Abbreviations: AA, acute appendicitis; FC, fecal calprotectin; AUC, area under the curve; CT, computed tomography; OTV, onset to visit; WBC, white blood cell count; CRP, C-reactive protein; ALT, alanine aminotransferase; IBD, inflammatory bowel disease. ⇑ Corresponding author at: Department of General Surgery, The Fifth Pepple’s Hospital of Wujiang Area, 555 Xinyou Road, Wujiang District, Suzhou, Jiangsu 215211, People’s Republic of China. E-mail address: [email protected] (Y. Pang). 1 Wenqing Zhou and Huiying Qiao contributed equally to this work.
women of reproductive age [3,4]. The main reason for this unsatisfactory outcome is that various pathologies in the abdomen can appear similar to the signs and symptoms of AA [5]. Nowadays, how to diagnose patients with AA more accurately is still challenging. In the past two decades, it has been reported that computed tomography (CT) can increase the specificity of diagnostic evaluation and reduces the rate of negative appendectomy [6]. However, CT has disadvantages that include the potential for inaccurate interpretation, exposure to radiation, and delay in definitive treatment for AA [7]. More importantly, equipment and qualified personnel for CT is not available universally in all hospitals, especially in emergency department of primary hospitals. Given these drawbacks, sensitive, economical and accurate markers that can help in the preoperative screening of patients with suspected AA are thus mandatory. Calprotectin is a 36.5 kDa calcium- and zinc-binding heterodimer that has been found as the major cytosolic protein in neutrophil granulocytes [8]. In previous studies, fecal calprotectin
https://doi.org/10.1016/j.ajem.2019.10.022 0735-6757/Ó 2019 Published by Elsevier Inc.
Please cite this article as: W. Zhou, H. Qiao, W. Yuan et al., Diagnostic utility of fecal calprotectin in patients presenting to the emergency department with suspected acute appendicitis, American Journal of Emergency Medicine, https://doi.org/10.1016/j.ajem.2019.10.022
2
W. Zhou et al. / American Journal of Emergency Medicine xxx (xxxx) xxx
(FC) has been mainly proposed as a marker for the diagnosis and follow-up of many bowel pathologies [8,9]. Recently, high calprotectin activity was confirmed within the lumen of vermiform appendix specimens following appendectomy for AA [9]. Here, we postulated that changes of the calprotectin expression can be transferred to the colonic lumen by inflammatory cells, making FC potentially useful for diagnosing patients with suspected AA.
Receiver-operating characteristic (ROC) curves were performed to evaluate the utility of FC value for the diagnosis of AA. In addition, optimal cut-point of FC value for identifying or excluding risk of AA were identified. These analyses were performed with R soft-
2. Methods
Total 84 eligible patients were enrolled in the current study. Among these patients, 2 patients underwent negative appendectomy. In addition, 3 patients with AA were initially misdiagnosed until further close observation. Finally, total of 40 (35%) patients had the diagnosis of AA, and the remaining 44 (59%) did not have AA at this emergency room visit. Comparisons of clinical characteristics between these two groups are presented in Table 1. No statistically significant difference was determined between the groups in terms of age, sex, onset to visit (OTV) interval and the ratio of pregnant patients. In addition, the symptoms represent the ‘‘classic” presentation of AA, such as nausea, vomiting and fever, were also occupied similar proportion in the no AA group (all of P < 0.05). As expected, WBC count, CRP value, and FC value in AA group were found to be higher than in no AA group. The relationship between preoperative FC value and the risk of AA was showed in Fig. 2. ROC analyses demonstrated FC value to be highly sensitive and specific for the diagnosis of AA, as indicated by an overall AUC of 0.928 (500 times of boot strap estimated 95% CI, 0.855–0.972), with an optimal cut point of 106 ug/g, which was sensitive and specific for ruling in the diagnosis of AA. Postoperative pathological specimens of 40 patients with appendicitis were retrospectively reviewed. Overall, we recorded a significant positive correlation between FC value and the severity of AA. FC levels in 26 patients with simple AA were significantly lower than it in the remaining 14 patients with suppurative AA (206 vs. 304ug/g, P = 0.001, Fig. 3).
2.1. Ethics The study was conducted in accordance with the ethical principles of the Declaration of Helsinki and the principles of Good Clinical Practice. The institutional review board of the Wujiang District Fifth People’s Hospital approved all investigational procedures involved in this study. A written consent was obtained from all patients before taking the specimen and patient data was anonymous prior to analysis. 2.2. Study population. The current study population was drawn from consenting adult patients (age 18 years) who presented to the emergency department of the Wujiang District Fifth People’s Hospital and with a complaint of abdominal pain in the year of 2018. Exclusion criteria for the study were previous history of abdominal disease; gastrointestinal diseases or using non-steroidal anti-inflammatories or proton pump inhibitors; inflammatory bowel disease; abdominal pain for more than 72 h; patients who have received anti-inflammatory treatment and those who could not provide stool specimens. 2.3. Data collection Clinical characteristics of each patient were recorded in detail, including demographics, symptoms, signs, medical history, medication use, and any imaging tests in the emergency department including ultrasound and CT. The diagnosis process for patients with abdominal pain in our hospital was showed in Fig. 1. Patients with suspected AA received laparoscopic appendectomy under general anesthesia. The entire perioperative treatment process is basically the same as described in previous article [10]. 2.4. Determination of diagnosis: A week follow-up was performed on every patient to determine any clinical events occurred during the period and whether there is a misdiagnosis. Follow up results and the pathological test results of the surgical specimen determined the final diagnosis. 2.5. FC analysis FC testing was performed with a commercially available diagnostic Kit (Coloidal Gold) for Calprotectin (Xiamen Wiz Biotech co. LTD, China) according to established methods. We measured FC value at the time of patient visits and glycerin suppository is used if necessary. 2.6. Statistical analysis: Comparisons of clinical characteristics between patients who had AA and those who did not were performed with chi-square tests for categorical data and student t tests for continuous data. A two-sided p value of <0.05 was considered significant.
ware (version 3.40, http://www.R-project.org). 3. Results
4. Discussion Despite being a common disease, the absence of reliable discriminators for the diagnosis of AA still exists. In the current study, we demonstrated that FC would be an effective predictor of AA. Therefore, the combination of FC value plus standard clinical assessment should be promoted to reduce the number of patients with negative appendectomy and misdiagnosis. Previous studies regarding FC have largely focused on the gastrointestinal disorders, especially inflammatory bowel disease (IBD). It has an established role as a diagnostic modality and a biomarker of disease activity in patients with IBD, with high sensitivity and specificity [11–13]. Theoretically, FC is secreted by activated macrophages and neutrophils and acts by inducing leukocyte recruitment and the secretion of pro-inflammatory cytokines [14]. Therefore, the concentration of FC reflects the extent of neutrophil migration to the gastrointestinal tract [15]. During the procession of AA, an inflammation of the appendix is significantly associated with changes in the expression of calprotectin [16]. The inflammatory cells then transferred from the lumen of the vermiform appendix into the colonic lumen, causing calprotectin from such cells being detectable in feces [17]. It is thus logically explained the results found in the current study that patients with AA have significant higher FC levels. Pathological specimen from AA patients showed the degree of infiltration of inflammatory cells is positively correlated with FC value. This also indirectly suggested the hypothesis as we discussed above. In adult patients, CT has also been widely used to diagnose AA, but there are shortcomings such as radiation, high cost and inconvenience [2]. Our results provide another simple, cheap and conve-
Please cite this article as: W. Zhou, H. Qiao, W. Yuan et al., Diagnostic utility of fecal calprotectin in patients presenting to the emergency department with suspected acute appendicitis, American Journal of Emergency Medicine, https://doi.org/10.1016/j.ajem.2019.10.022
W. Zhou et al. / American Journal of Emergency Medicine xxx (xxxx) xxx
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Fig. 1. General approach to the patient with suspected acute appendicitis in the emergency department.
Table 1 Clinical characteristics of patients who had abdomen pain with or without AA.
FC (lg/g) WBC (10–9/ml) CRP (mg/dL) Age (years) Sex (female,%) OTV interval (hours) Pregent (%) Nausea/vomiting (%) Fever (%) ALT > 40 (%) Imaging positive (%)
No AA
AA
(N = 44) 68.5 (44.0) 10.1(4.4) 17.2 (14.7) 46 (17) 23 (52.3) 32 (21) 11 (25.0) 31 (70.5) 14 (31.8) 13 (29.5) 2 (4.5)
(N = 40) 240.5 (94.5) 17.6 (7.0) 33.7 (18.8) 49 (17) 19 (47.5) 31 (20) 6 (15.00) 28 (70.0) 19 (47.5) 11 (27.5) 37 (92.5)
P-value <0.001* <0.001* <0.001* 0. 466 0. 662 0.782 0.255 0.964 0.142 0.836 <0.001*
Significant difference. Abbreviations: AA, acute appendicitis; FC, fecal calprotectin; WBC, white blood cell count; CRP, C-reactive protein; OTV, onset to visit; ALT, alanine aminotransferase.
nient alternative that achieves the similar accuracy. This is especially important not only for hospitals that cannot provide CT examinations but also for those patients who are not suitable to exposed to radiation, such as pregnant women. Currently, diagno-
sis of AA can be particularly challenging during pregnancy because of the overlapping of symptoms between appendicitis and pregnancy [18]. In a study of 94,489 patients, appendectomy for perforated appendicitis resulted in up to 6% fetal loss and 11% early delivery; for negative appendectomy, the fetal loss rate and early delivery rate were 4% and 10%, respectively [19]. Therefore, FC measurement is to be expected to improve this status in the future. In clinical practice, the greatest obstacle to applicate FC may be the potential difficulty and time delay in obtaining stool specimens from emergency department patients. Actually, previous studies showed that calprotectin is resistant to proteolytic degradation and can be stable for up to 7 days in stool samples at room temperature [20]. A sample of less than 5 g is sufficient for reliable measurements [20]. In addition, a number of commercial assays are available for simple and rapid measurement of calprotectin [21,22]. These qualities open up room for a quick analysis in the emergency department without waste of time, such as collect fecal samples at home or obtain small amount of specimens by glycerin suppository. Therefore, further research projects relevant to every step of the specimen collection should be promoted to modernize and standardize the diagnosis of AA. Two main limitations in this study must be mentioned. First, it occurred in a single center and only include the small number of
Please cite this article as: W. Zhou, H. Qiao, W. Yuan et al., Diagnostic utility of fecal calprotectin in patients presenting to the emergency department with suspected acute appendicitis, American Journal of Emergency Medicine, https://doi.org/10.1016/j.ajem.2019.10.022
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W. Zhou et al. / American Journal of Emergency Medicine xxx (xxxx) xxx
Funding This work was supported by the Science and Education Foundation of Wujiang district (wwk201725). Declaration of Competing Interest Authors reported no conflict of interest. References
Fig. 2. The relationship between fecal calprotectin value and the risk of acute appendicitis. Fecal calprotectin was highly sensitive and specific for the diagnosis of acute appendicitis, with a highly significant area under the curve of 0.928 (95% CI, 0.855–0.972). The blue shading shows the 500 times of bootstrap estimated 95% CI with the area under the curve. The cut off points of 106 ug/g was optimal in the current study.
Fig. 3. FC levels in patients with simple acute appendicitis and patients with suppurative acute appendicitis. The mean fecal calprotectin was 206 lg/g in 26 patients with simple appendicitis acute appendicitis; The mean fecal calprotectin was 304 lg/g in the remaining 14 patients with suppurative acute appendicitis patients (206 vs.304 lg/g, P = 0.001).
patients with AA. Thus, whether the present findings apply to other regions with different prevalence of AA and patients with different clinical characteristics still need verified by larger multicenter cohorts. Second, although our study found the cutoff value of FC to about 100 ug /g (109 ug / g) strongly suggests the high risk of AA. It is of note that there are quantitative differences between the available FC commercial assays today [23,24]. Therefore, this cut-off values may not be suitable for other assays.
5. Conclusion In conclusion, the evidence overall suggests that FC can be a helpful biomarker for identifying AA. When examining patients for clinically suspected AA, FC test provides a sensitive, convenient and economical method to help facilitate the diagnosis. More timely and accurate diagnosis will help reduce the risks of perforation or unnecessary operation thus improve overall outcomes.
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Please cite this article as: W. Zhou, H. Qiao, W. Yuan et al., Diagnostic utility of fecal calprotectin in patients presenting to the emergency department with suspected acute appendicitis, American Journal of Emergency Medicine, https://doi.org/10.1016/j.ajem.2019.10.022