Urinary biomarkers in pediatric appendicitis

Leucine-Rich Alpha-2-Glycoprotein as a non-invasive biomarker for pediatric acute appendicitis: a systematic review and meta-analysis

The aim of this study was to analyze the diagnostic performance of Leucine-Rich Alpha-2-Glycoprotein (LRG1) in pediatric acute appendicitis (PAA). We conducted a systematic review of the literature in the main databases of medical bibliography. Two independent reviewers selected the articles and extracted relevant data. Methodological quality was assessed using the QUADAS2 index. A synthesis of the results, standardization of the metrics and 4 random-effect meta-analyses were performed. Eight studies with data from 712 participants (305 patients with confirmed diagnosis of PAA and 407 controls) were included in this review. The random-effect meta-analysis of serum LRG1 (PAA vs control) resulted in a significant mean difference (95% CI) of 46.76 μg/mL (29.26-64.26). The random-effect meta-analysis for unadjusted urinary LRG1 (PAA vs control) resulted in a significant mean difference (95% CI) of 0.61 μg/mL (0.30-0.93). The random-effect meta-analysis (PAA vs control) for urinary LRG1 adjusted for urinary creatinine resulted in a significant mean difference (95% CI) of 0.89 g/mol (0.11-1.66).   Conlusion: Urinary LRG1 emerges as a potential non-invasive biomarker for the diagnosis of PAA. On the other hand, due to the high between-study heterogeneity, the results on serum LRG1 should be interpreted with caution. The only study that analyzed salivary LRG1 showed promising results. Further prospective studies are needed to confirm these findings. What is Known: • Pediatric acute appendicitis continues to be a pathology with a high rate of diagnostic error. • Invasive tests, although useful, are a source of stress for patients and their parents. What is New: • LRG1 emerges as a promising urinary and salivary biomarker for the noninvasive diagnosis of pediatric acute appendicitis.

Diagnostic Accuracy of Leucine-Rich α-2-Glycoprotein 1 as a Non-Invasive Salivary Biomarker in Pediatric Appendicitis

The aim of this study is to evaluate the diagnostic accuracy of leucine-rich α-2-glycoprotein 1 (LRG1) in saliva as a novel biomarker for acute appendicitis in the pediatric population. From October 2021 to June 2022, 92 children aged 5 to 17 years who presented with acute abdomen and suspected acute appendicitis were enrolled in this prospective study. The parameters documented included demographic and clinical information, as well as operative and postoperative data. Patients were divided into two groups: those with acute appendicitis who underwent laparoscopic appendectomy (n = 46) and those without appendicitis (n = 46). The total white blood cell (WBC) count, percent of neutrophils, C-reactive protein (CRP) level, and salivary LRG1 were compared between groups. A commercially available enzyme-linked immunosorbent assay (ELISA) LRG kit was used to measure the LRG levels. The median salivary LRG1 level was significantly higher in the group of children with pathohistologically confirmed acute appendicitis compared to the control group: 233.45 ng/mL (IQR 114.9, 531.2) vs. 55.95 ng/mL (IQR 51.5, 117.9), p < 0.001. LRG1 had an overall good receiver-operator characteristic area under the curve of 0.85 (95% CI 0.76-0.92; p < 0.001). The optimal LRG1 cutoff with best separation between acute appendicitis and the controls was >352.6 ng/mL (95% CI from >270.7 to >352.6). Although the specificity was 100% at this cutoff, the sensitivity for identifying appendicitis was 36%. In addition, a significant difference was found between groups in the laboratory values of all inflammatory markers tested: WBC, absolute neutrophil count, and CRP (p < 0.001 for all). Although LRG1 in saliva showed a good AUC parameter and significantly higher values in patients with acute appendicitis compared to the controls, its usefulness in the patient population who present at emergency departments with abdominal pain is debatable. Future studies should focus on investigating its diagnostic potential.

Diagnostic Utility of Serum Leucine-Rich α-2-Glycoprotein 1 for Acute Appendicitis in Children

PURPOSE

The aim of this study is to assess the diagnostic utility of serum leucine-rich α-2-glycoprotein 1 (LRG1) in pediatric patients with acute abdominal pain, admitted to the emergency surgical unit, in order to make a prompt and accurate diagnosis of acute appendicitis.

PATIENTS AND METHODS

Pediatric patients older than 5 years of age who presented to the emergency department from 15 October 2021 to 30 June 2022 with acute abdominal pain and suspected acute appendicitis were prospectively recruited in the study. Demographic and clinical data, as well as operative and postoperative data, were recorded. A total of 92 patients were equally distributed into two groups: children with acute appendicitis who underwent laparoscopic appendectomy and non-appendicitis patients, presenting with non-specific abdominal pain. LRG1 levels were determined using a commercially available LRG1 enzyme-linked immunosorbent assay (ELISA) kit. Serum LRG1 levels, as well as other inflammatory markers (white blood cell count (WBC), C-reactive protein (CRP) and absolute neutrophil count) were compared between groups.

RESULTS

The median level of LRG1 in serum was significantly higher in the group of children with pathohistologically confirmed acute appendicitis than in the control group, at 350.3 µg/mL (interquartile range (IQR) 165.2-560.3) and 25.7 µg/mL (IQR 14.7-36.8) (p < 0.001), respectively. Receiver operating characteristic area under the curve for LRG1 from serum was 1.0 (95% CI 0.96-1.00; p < 0.001) and the value of >69.1 µg/mL was found to perfectly separate acute appendicitis cases from controls. Additionally, as expected, each of the examined laboratory inflammatory markers provided a significantly higher values in the acute appendicitis group compared to the control group: WBC 14.6 × 10⁹/L (IQR 12.7, 18.7) vs. 7.0 × 10⁹/L (IQR 5.4, 9.0) (p < 0.001), CRP 16.3 mg/dL (IQR 6.9, 50.4) vs. 2.2 mg/dL (IQR 2, 2) (p < 0.001) and absolute neutrophil count 84.6% (IQR 79.5, 89.0) vs. 59.5% (IQR 51.5, 68.6) (p < 0.001).

CONCLUSIONS

LRG1 in the serum was found to be a promising novel biomarker, with excellent differentiation of acute appendicitis from non-appendicitis cases in children presenting with non-specific abdominal pain.

Diagnostic performance of calprotectin and APPY-1 test in pediatric acute appendicitis: a systematic review and a meta-analysis

BACKGROUND

Pediatric acute appendicitis (AA) is a challenging pathology to diagnose. In the last decades, multiple biomarkers have been evaluated in different human biological samples to improve diagnostic performance. This study aimed to examine the diagnostic performance of serum, fecal and urinary calprotectin as well as the role of the APPY-1 biomarker panel in pediatric acute appendicitis.

METHODS

We conducted a systematic review of the literature that involved an extensive search in the main databases of medical bibliography (Medline, PubMed, Web of Science and SciELO). Two independent reviewers selected the relevant articles based on the previously defined inclusion and exclusion criteria. Methodological quality of the selected article was rated using the QUADAS2 index. Data extraction was performed by two independent reviewers. A synthesis of the results, a standardization of the metrics and two random-effect meta-analyses, one for serum calprotectin and one for APPY-1, were performed.

RESULTS

The research resulted in 173 articles. Thirty-eight duplicates were removed. Among the remaining 135 articles, we excluded 125 following the inclusion and exclusion criteria, resulting in the 10 studies included in this review. This systematic review included data from of 3901 participants (1276 patients with confirmed diagnosis of AA and 2625 controls). The age of the participants ranged from 0 to 21 years. Four of the studies compared serum calprotectin values and reported significant differences between groups, but inconsistent results regarding cutoff points, sensitivity and specificity. Two publications compared urinary values of calprotectin and presented inconsistent results regarding sensitivity and specificity as well. One publication evaluated the diagnostic performance of fecal calprotectin, but it did not provide data on measured values. Four studies evaluated the diagnostic performance of APPY-1 test in pediatric acute appendicitis. The calculated pooled sensitivity and specificity of those studies were 97.37 (95% CI 95.60-98.44) and 36.74 (95% CI 32.28-41.44), respectively, and the calculated pooled NLR, 0.0714 (95% CI 0.041-0.115).

CONCLUSION

Serum calprotectin has limited diagnostic yield in pediatric acute appendicitis. Its performance seems to increase with the hours of clinical evolution and in advanced AA, although the evidence is limited. There is not enough evidence on the usefulness of urinary or fecal calprotectin in the diagnosis of pediatric acute appendicitis. On the other hand, the APPY-1 is a reliable test to exclude the diagnosis of AA in patients at low or moderate risk according to PAS and Alvarado Score.

The use of the ratio of C-reactive protein to albumin for the diagnosis of complicated appendicitis in children

PURPOSE

No reliably specific marker for complicated appendicitis has been identified. The ratio of serum C-reactive protein (CRP) to albumin (ALB) (CRP/ALB ratio) is a new inflammation-based prognostic score that is associated with the severity of inflammation. The aim of this study was to evaluate the predictive value of CRP/ALB ratio for the diagnosis of complicated appendicitis in children.

METHODS

A retrospective study of 296 children with acute appendicitis was conducted with assessments of demographic data, clinical symptoms, pre-operative laboratory results, abdominal ultrasound examinations and clinical outcomes. According to the postoperative pathological results, patients were divided into a simple appendicitis group (169 patients) and a complicated appendicitis group (127 patients). SPSS version 22.0 was used to analyse the data.

RESULTS

Of the 296 patients, CRP/ALB ratio was higher in complicated appendicitis than in simple appendicitis (P < 0.05). Logistic regression analysis showed that higher levels of white blood cell count (WBC), CRP, CRP/ALB ratio, and increased incidence in submucosal layer loss and appendicolith were independent risk factors for complicated appendicitis in children. Receiver operating characteristic curve analysis showed that the area under the curve of the CRP/ALB ratio (0.883) was larger than that of WBC (0.702), CRP (0.802), ALB (0.835), submucosal layer loss (0.633) and appendicolith (0.673). A CRP/ALB ratio ≥ 1.39 was found to be a significant marker in the prediction of complicated appendicitis, with 86.61% sensitivity and 84.62% specificity. Patients with a CRP/ALB ratio ≥ 1.39 had a 31.263 times higher chance of having complicated appendicitis (95% CI: 16.449-59.418) than those with a CRP/ALB ratio < 1.39.

CONCLUSION

The admission CRP/ALB ratio was significantly higher in children with complicated appendicitis. The CRP/ALB ratio is a novel but promising haematological marker that aids in the differentiation of acute complicated and simple appendicitis.

Diagnostic accuracy of Leucine-rich α-2 glycoprotein (LRG) as a urinary biomarker in pediatric appendicitis: a prospective observational pilot study from Eastern India

Background

Recently, several serum and urinary biomarkers have been investigated for diagnosis of acute appendicitis. Urinary biomarkers seem to be advantageous in children as it is non-invasive, painless, and easy to perform. Leucine-rich α-2-glycoprotein (LRG) is regarded as a reliable urinary biomarker for the diagnosis of pediatric appendicitis. A prospective observational pilot study was conducted in children presenting with abdominal pain. Assessment of pediatric appendicitis score (PAS), routine blood tests, and measurements of urinary LRG was done. The present study aimed to evaluate the diagnostic accuracy of urine LRG in appendicitis in Indian children and to assess the concentration of urine LRG at which it will guide the management.

Results

LRG had a receiver operating characteristic (ROC) area under the curve (AUC) of 0.586 (95% CI 0.407–0.766). There was no specific cut-off identified using Youden’s index. ROC analysis of the PAS score resulted in an AUC of 0.821 (95% CI 0.691–0.952). Using Youden’s index, the cut-off for PAS scoring was identified as 6.5 with the sensitivity of 80%, the specificity of 76.2%, positive predictive value 76.19%, negative predictive value as 80%, and diagnostic accuracy of 78%.

Conclusions

LRG could not show better diagnostic performance compared to routine blood tests and PAS scores. There was no specific cut-off value at which it will differentiate mesenteric adenitis and acute appendicitis and guide their management. With 78% diagnostic accuracy, PAS score (> 6) is still a better tool for the diagnosis of acute appendicitis.

Trial registration

Clinical Trials Registry Government of India, CTRI/2018/01/011182, Registered on: 08 Jan 2018.

Serum and Urine Biomarker Leucine-Rich Alpha-2 Glycoprotein 1 Differentiates Pediatric Acute Complicated and Uncomplicated Appendicitis

PURPOSE

This prospective, single-center cohort study analyzes the potential of inflammatory protein mediator leucine-rich alpha-2 glycoprotein 1 (LRG1) for the early and accurate diagnosis of acute appendicitis (AA), and differentiation of acute complicated (AcA) from uncomplicated appendicitis (AuA).

METHODS

Participants were divided into the AcA, AuA, and control groups, and their serum (s-LRG1) and urine LRG1 (u-LRG1) levels were assayed preoperatively on the second and fifth postoperative days.

RESULTS

153 patients participated, 97 had AA. Preoperative u-LRG1 with a cut-off value of 0.18 μg/mL generated an area under the receiver operated characteristic (AUC) curve of 0.70 (95% CI 0.62-0.79) for AA versus control (p < 0.001), while the results for AcA versus AuA were not significant (AUC 0.60, 95% CI 0.49-0.71, p = 0.089). The s-LRG1 levels of AA versus the control with a cut-off value of 51.69 μg/mL generated an AUC of 0.94 (95% CI 0.91-0.99, p < 0.001). The cut-off value of s-LRG1 was 84.06 μg/mL for diagnosis of AcA from AuA, and therefore, significant (AUC 0.69, 95% CI 0.59-0.80, p = 0.001).

CONCLUSIONS

LRG1 exhibited excellent diagnostic performance as an inexpensive, non-invasive, rapid, and accurate biomarker able to reflect the pathogenesis of AA. LRG1 has the potential to replace advanced imaging to diagnose clinically ambiguous AA cases.

Comparison of leucine-rich alpha-2-glycoprotein-1 (LRG-1) plasma levels between patients with and without appendicitis, a case-controlled study

Acute appendicitis (AA) is the first cause of emergency surgery. Leucine-Rich Alpha-2-Glycoprotein 1 (LRG1) has been shown to be a potential biomarker in cases of AA in children, but there are conflicting results for its use in adults. The objective of this study is to compare the median plasma values of LRG1 in patients with acute abdomen with and without appendicitis. This case–control study was conducted prospectively at the emergency room (ER) of a tertiary teaching hospital, between March 1st, 2011 and December 31st, 2012. Patients with recent abdominal pain, aged 18–70 years who attended at the ER were included in the study. Blood samples were drawn at the first presentation. Those who were submitted to surgery and had a pathology report of AA were considered as cases. Those without a need for surgery and treated for other conditions, e.g., pelvic inflammatory disease, were considered as controls. Follow-up in controls was made up to 30 days. LRG1 plasma median values were measured using an ELISA kit and compared between groups. A total of 28 participants, 14 cases with acute appendicitis and 14 controls, were included. The median (range) values of leucine-rich alpha-2-glycoprotein-1 level in the group with appendicitis and control group were 8.8 ng/ml (5.5–31) and 11 (4.6–108) ng/ml, respectively (Mann–Whitney test P = 0.26). Median plasma leucine-rich alpha-2-glycoprotein-1 levels were not useful in diagnosing Acute Appendicitis in patients with acute abdominal pain.

A Pilot Study Evaluating Novel Urinary Biomarkers for Crohn's Disease

Introduction

Although collecting faeces and blood samples are considered non-invasive methods of monitoring Crohn's disease (CD), these methods are less preferred by some patients. This study utilized urine as an alternative to evaluate four disease biomarkers in young adults with active CD before and after exclusive enteral nutrition (EEN) therapy.

Methods

Urine samples collected at baseline (W0) and after 8 weeks (W8) of EEN therapy were assayed by ELISA for levels of intestinal fatty acid-binding protein (I-FABP), liver fatty acid-binding protein (L-FABP), claudin-3, and calprotectin. Levels of each biomarker were also compared with standard clinical parameters, including disease indexes, nutrient, and inflammatory markers.

Results

Of the paired urine samples from 14 patients, 10 were female and 12 were newly diagnosed with CD. Urinary I-FABP: Cr (standardized to urine Cr) levels were significantly reduced, while urinary L-FABP: Cr levels increased following EEN therapy. Urinary L-FABP: Cr correlated positively with serum insulin-like growth factor 1 (IGF-1) (r = 0.60, p = 0.02). Urinary CLND3: Cr and calprotectin: Cr levels were not significantly different after treatment.

Conclusion

I-FABP is a potential urinary biomarker of disease activity in adults with CD, while urinary L-FABP may be an indirect marker of nutritional status in adults with CD. CLND3 and calprotectin do not appear to have roles as urinary biomarkers in CD. These findings warrant further investigations using a larger sample size.

A clinical prediction model for complicated appendicitis in children younger than five years of age

Background

No reliably specific method for complicated appendicitis has been identified in children younger than five years of age. This study aimed to analyze the independent factors for complicated appendicitis in children younger than five years of age, develop and validate a prediction model for the differentiation of simple and complicated appendicitis.

Methods

A retrospective study of 382 children younger than five years of age with acute appendicitis from January 2007 to December 2016 was conducted with assessments of demographic data, clinical symptoms and signs, and pre-operative laboratory results. According to intraoperative findings and postoperative pathological results, acute appendicitis was divided into simple and complicated appendicitis. Univariate and multivariate analyses were used to screen out the independent factors of complicated appendicitis, and develop a prediction model for complicated appendicitis. Then 156 such patients from January 2017 to December 2019 were collected as validation sample to validate the prediction model. Test performance of the prediction model was compared with the ALVARADO score and Pediatric Appendicitis Score (PAS).

Results

Of the 382 patients, 244 (63.9%) had complicated appendicitis. Age, white blood cell count, and duration of symptoms were the independent factors for complicated appendicitis in children younger than five years of age. The final predication model for complicated appendicitis included factors above. In validation sample, the prediction model exhibited a high degree of discrimination (area under the curve [AUC]: 0.830; 95% confidence interval [CI]: 0.762–0.885) corresponding to a optimal cutoff value of 0.62, and outperformed the PAS (AUC: 0.735; 95% CI: 0.658–0.802), ALVARADO score (AUC: 0.733; 95% CI: 0.657–0.801).

Conclusion

Age, white blood cell count, and duration of symptoms could be used to predict complicated appendicitis in children younger than five years of age with acute appendicitis. The prediction model is a novel but promising method that aids in the differentiation of acute simple and complicated appendicitis.

Salivary biomarker for acute appendicitis in children: a pilot study

PURPOSE

Assays of salivary biomarkers for diagnosis are gaining popularity in pediatric diseases due to their non-invasive nature. Our pilot project aims to evaluate the utility of salivary leucine-rich-alpha-2-glycoprotein (LRG) in the diagnosis of pediatric acute appendicitis (AA).

METHODS

We prospectively recruited 34 patients, aged between 4 and 16 years, admitted with acute abdominal pain suspicious of appendicitis. The patients' demography, clinical characteristics, laboratory investigations, imaging examination results, operative findings, and discharge diagnoses were recorded. We compared the diagnostic performance of the patients' total white counts, neutrophil percentages, C-reactive protein, and saliva LRG levels. Saliva samples were obtained using the SalivaBio Children's Swab and LRG levels were quantified using a commercially available LRG enzyme-linked immunosorbent assay (ELISA) kit. IRB approval was obtained.

RESULTS

Seventeen patients had a confirmed diagnosis of appendicitis on histology. Another 17 were confirmed not to have appendicitis after a minimum of 24 h of hospitalization, with further verification via telephone interview 2 weeks later. The median levels of saliva LRG were elevated in patients with AA as compared to those without (P = 0.008). At a cutoff of LRG 0.33 ng/μg, we obtained a diagnostic specificity of 100% and sensitivity of 35.3%.

CONCLUSION

Our proof-of-concept study demonstrated the diagnostic potential of saliva LRG for appendicitis in children. The distinct advantage of saliva LRG assays is that the procedure is simple, pain-free, and requires no specialized skill. Further study with a larger cohort is needed to verify our results.

Leucine-rich α2-glycoprotein-1 upregulation in plasma and kidney of patients with lupus nephritis

BACKGROUND

Increased leucine-rich α2-glycoprotein-1 (LRG1) has been observed in various inflammatory and autoimmune diseases. We aimed to explore the expression and role of LRG1 in lupus nephritis (LN).

METHODS

Plasma LRG1 (pLRG1) was measured by enzyme-linked immunosorbent assay in 101 patients with renal biopsy-proven LN and 21 healthy controls (HC). Relationships between pLRG1 and clinical and pathological characteristics were analyzed. The expression of LRG1 in peripheral blood leukocytes and kidney was detected by flow cytometry, immunohistochemistry and immunofluorescence, respectively. Further cell experiments were focused on the role of LRG1.

RESULTS

We found that LRG1 was expressed in plasma, some peripheral blood leukocytes, proximal tubule and several inflammatory cells. The levels of LRG1 in plasma, peripheral blood leukocytes and kidney were elevated in LN patients as compared to HC. Plasma expression levels of LRG1 correlated positively with renal function and renal disease activity, and reflect specific pathologic lesions in the kidneys of patients with LN. Interleukin-1β and interleukin-6, not tumor necrosis factor-α and interferon γ induced the LRG1 expression in human renal tubular epithelial cell line. Moreover, stimulation of recombinant human LRG1 could inhibit late apoptosis, promote proliferation and regulate expression of inflammatory factors and cytokines.

CONCLUSIONS

Plasma expression levels of LRG1 were associated with renal function, disease activity, and pathology in LN. It might also be involved in renal inflammation, proliferation and apoptosis of endothelial cells. LRG1 might be a potential prognosis novel predictor in LN patients.

A novel noninvasive appendicitis score with a urine biomarker

PURPOSE

The aim of our study was to develop an appendicitis score incorporating a urine biomarker, Leucine rich alpha-2-glycoprotein (LRG), for evaluation of children with abdominal pain.

METHODS

From January to August 2017 we prospectively enrolled children aged 4-16 years old admitted for suspected appendicitis. Urine samples for LRG analysis were obtained preoperatively and quantified by enzyme-linked immunosorbent assay (ELISA) after correction for patient hydration status. The diagnosis of appendicitis was based on operative findings and histology. Logistic regression was used to identify prospective predictors.

RESULTS

A total of 148 patients were recruited, of which 42(28.4%) were confirmed appendicitis. Our Appendicitis Urinary Biomarker (AuB) model incorporated urine LRG with 3 clinical predictors: 'constant pain', 'right iliac fossa tenderness', 'pain on percussion'. Area under the ROC curve for AuB was 0.82 versus 0.78 for the Pediatric Appendicitis Score (PAS) on the same cohort of patients. A model-calculated risk score of <0.15 is interpreted as low risk of appendicitis. Sensitivity for the AuB at this cutoff was 97.6%, specificity 37.7%, negative predictive value 97.6%, positive predictive value 38.3%, and negative likelihood ratio 0.06.

CONCLUSION

The noninvasive AuB score appears promising as a diagnostic tool for excluding appendicitis in children without the need for blood sampling.

TYPE OF STUDY

Study of diagnostic test.

LEVEL OF EVIDENCE

Level III.

Diagnostic Accuracy of Serum and Urine S100A8/A9 and Serum Amyloid A in Probable Acute Abdominal Pain at Emergency Department

Study Design

This study was performed to investigate the diagnostic values of some inflammatory biomarkers in abdominal pain.

Methods

Patients over 18 years of age with acute recent abdominal pain who presented to the Emergency Department were evaluated. Serum and urinary samples were taken and evaluated for serum and urine S100A8/A9 and serum amyloid A. All patients were referred to a surgeon and were followed up until the final diagnosis. In the end, the final diagnosis was compared with the levels of biomarkers.

Results

Of a total of 181 patients, 71 underwent surgery and 110 patients did not need surgery after they were clinically diagnosed. Mean levels of serum and urine S100A8/A9 had a significant difference between two groups, but serum amyloid A did not show. The diagnostic accuracy of serum S100A8/A9, urine S100A8/A9, and serum amyloid A was 86%, 79%, and 50%, respectively, in anticipation of the need or no need for surgery in acute abdominal pain.

Conclusions

Our study showed that in acute abdominal pain, serum and urine S100A8/A9 can be useful indicators of the need for surgery, but serum amyloid A had a low and nonsignificant diagnostic accuracy.