Establishing a pediatric reference interval for plasma calprotectin.

Plasma calprotectin is a promising new biomarker of inflammatory activity and has been found to correlate well with clinical and endoscopic activity in children and adolescents with inflammatory bowel disease. A pediatric reference interval for plasma calprotectin has not been established for the Phadia 250 EliA™ Calprotectin fluoroenzyme immunoassay. In studies regarding pre-analytical properties, excellent precision and stability was found. However, sensitivity to hemolysis was demonstrated. We identified pediatric blood samples from apparently healthy children who were referred by their general practitioner for blood sampling including measurement of hemoglobin (Hb) and C-reactive protein (CRP). We excluded samples from children who had undergone additional blood sampling within 2 months before or after the index sample, if Hb was outside of local reference ranges or CRP levels were above the lower limit of the measuring interval (LLM), and any samples with a hemolysis above 0.02 mmol/L. Using this algorithm, we identified 141 blood samples. No outliers were identified. We established the following reference intervals according to CLSI C28-A3 using non-parametric statistics: 1-17 years: 16-246 µg/L. Our results may prove useful for further utilization of plasma calprotectin as a marker of inflammation in children and adolescents with inflammatory disorders.

Diagnostic accuracy of high-resolution peripheral quantitative computed tomography and X-ray for classifying erosive rheumatoid arthritis.

OBJECTIVE: To investigate whether high-resolution peripheral quantitative CT (HR-pQCT) of two metacarpophalangeal (MCP) joints can more accurately classify patients as having erosive RA compared with conventional radiography (CR) of 44 joints in the hands, wrists and feet. METHODS: In this single-centre cross-sectional study, patients with established RA (disease duration ≥5 years) were investigated by HR-pQCT and CR. The second and third MCP joints of the dominant hand were assessed for erosions by HR-pQCT. CR of the hands, wrists and feet were scored according to the Sharp-van der Heijde (SHS) method. RESULTS: In total, 353 patients were included; 66 (18.7%) patients were classified as having non-erosive RA, and 287 (81.3%) had erosive RA by CR. The sensitivity and specificity (95% CI) of HR-pQCT for classifying patients as having erosive RA when standard CR of hands, wrists and feet was used as the reference was 89% (84, 92%) and 30% (20, 43%), respectively. Using HR-pQCT as the reference, the sensitivity and specificity of CR for classifying patients having erosive RA were 85% (80, 89%) and 38% (25, 52%), respectively. McNemar's χ2 test showed no significant difference between the sensitivities of patients classified as having erosive RA by HR-pQCT or by CR (2.14, P = 0.177). CONCLUSION: The diagnostic accuracy of HR-pQCT scanning of only two MCP joints and CR of 44 joints suggests the two modalities were comparable for classifying patients with established RA as having erosive disease. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov (NCT03429426).

Plasma calprotectin - preanalytical stability and interference from hemolysis.

As an activation product of neutrophil granulocytes, calprotectin has been widely used in fecal samples for diagnosis and monitoring of patients with inflammatory bowel disease. However, fecal sample collection is cumbersome, and pre-analytical sources of error are plentiful. Therefore, plasma calprotectin is being investigated as a promising new biomarker. To utilize any biomarker, pre-analytical factors such as stability and susceptibility to interference from hemolysis must be established. We present precision estimates, stability results as well as interference study on plasma calprotectin in EDTA-plasma using the Thermo Fischer Phadia 250 EliATM Calprotectin immunoassay. Precision was estimated by the use of patient pools as well as internal quality controls provided by the manufacturer. Coefficients of variance were below 6.9% for patient samples. Calprotectin was stable in EDTA plasma after storage at 5-8 °C for up to 4 days, as well as after long-term storage at -20 °C. Susceptibility to interference from hemolysis was high, especially for low concentrations of calprotectin (<50 ng/mL) where hemoglobin levels above 0.02 mmol/L lead to false increase in calprotectin concentrations of up to 100%.

The Minimal Erosive Volume Needed for Radiographic Identification of Erosions in the Metacarpophalangeal Joints in Patients With Rheumatoid Arthritis.

OBJECTIVE: To compare in images, obtained by high-resolution peripheral quantitative computed tomography (HR-pQCT) and conventional radiography (CR) of the second and third metacarpophalangeal (MCP) joints, the minimal erosive cortical break needed to differentiate between pathological and physiological cortical breaks. METHODS: In this single-center cross-sectional study, patients with established rheumatoid arthritis (disease duration ≥ 5 yrs) had their second and third MCP joints of the dominant hand investigated by HR-pQCT and CR. Empirical estimation was used to find the optimal cut-off value for the number of erosions and total erosive volume, which were detectable between patients with and without erosions in the second and third MCP joints according to CR. RESULTS: The total erosive volume in the second and third MCP joints by HR-pQCT for CR-detected erosive disease was estimated to be 56.4 mm3 (95% CI 3.5-109.3). The sensitivity and specificity at this cutpoint were 78% and 83%, respectively, with an area under the receiver-operating characteristic curve (AUC) of 0.81. The optimal cut-off value for the number of erosions by HR-pQCT was 8.5 (95% CI 5.9-11.1) for CR-detected erosive disease in the second and third MCP joints. The sensitivity and specificity at this cutpoint were 74% and 88%, respectively, with an AUC of 0.81. CONCLUSION: Erosions by HR-pQCT were larger in patients with erosive damage in the second and third MCP joints by CR. We found that CR had poor sensitivity for detecting erosive disease when the erosive volume was < 56.4 mm3 or the number of erosions was < 8.5.

Effect of radiographic disease severity in high-resolution quantitative computed tomography assessment of metacarpophalangeal joint erosion and cysts.

AIM: Bone erosions are the hallmark of rheumatoid arthritis (RA). High-resolution peripheral quantitative computed tomography (HR-pQCT) enables 3-dimensional visualization of arthritic bone erosions at a high resolution. However, the degree of erosive disease could influence the reliability of HR-pQCT evaluation. We aim to assess the intra- and inter-reader variability of identification of erosions in the metacarpophalangeal (MCP) joints using HR-pQCT in healthy controls and patients with RA, stratified according to van der Heijde-modified Sharp Score (HSS) of radiographic erosions. METHOD: We analyzed HR-pQCT images from 78 patients with RA and 25 healthy controls. Patients were allocated to one of three groups of mild, moderate or severe disease according to HSS of MCP joints 2 and 3. Total HR-pQCT scans were analyzed twice in random order by three experienced readers, blinded to group distribution. The number of cortical interruptions and their classification as either erosions or cysts according to predefined criteria were recorded. Intraclass correlation coefficients (ICC) for cortical interruptions, erosions and cysts were calculated for each group using a 2-way random-effects model for inter-reader ICC and a 2-way mixed-effects model for intra-reader ICC. RESULTS: The intra- and inter-reader ICC were good to moderate for cortical interruptions and moderate for erosions throughout disease severity groups. The ICCs for the identification of cysts decreased with increasing degree of erosive disease. CONCLUSION: The detection of cortical interruptions is only minimally affected by the degree of erosive damage, whereas the distinction between erosions and cysts is more complex in patients with extensive erosive disease.

The effect of glucocorticoids on bone mineral density in patients with rheumatoid arthritis: A systematic review and meta-analysis of randomized, controlled trials.

PURPOSE: The role of glucocorticoids in the treatment of rheumatoid arthritis (RA) is widely debated. Impairment of bone formation may be counter-balanced by reduced systemic inflammation. This review aims to assess the effect of prednisolone/prednisone on bone mineral density (BMD) in patients with RA analyzed in randomized, controlled trials. METHODS: We performed a systematic literature search and identified randomized, double-blinded placebo-controlled studies including patients with RA and using prednisolone or prednisone as the intervention. We selected studies that measured BMD by DXA at baseline and at least once thereafter. Two authors independently performed reference review, data extraction and risk of bias assessment. Primary outcome was mean change in BMD from baseline to follow-up. Secondary endpoints included radiographic scores, RA disease activity indices and fractures. We rated the quality of evidence using the GRADE approach. Outcomes were standardized for meta-analyses and 95% confidence intervals (95% CI) were calculated. RESULTS: We identified 7 studies and included previously unpublished data. Studies were similar regarding study population and intervention. Standard mean difference (SMD) in change in BMD from 0 to 24 months was -0.02 (95%CI -0.16, 0.12) at the lumbar spine and -0.11 (95% CI -0.25, 0.02) at the hip (both high quality evidence) between patients treated with prednisolone/prednisone or not. Data completeness was low in some studies, concomitant treatment of RA differed between studies and differences in use of anti-osteoporotic medication may have influenced the results. However, sensitivity analyses excluding studies in which participants used either the most or the least potent concomitant RA treatment or used anti-osteoporotic therapies did not alter the estimates. CONCLUSIONS: In patients with early and active RA, we found no difference in change in BMD between patients treated with prednisone/prednisolone versus placebo, suggesting that at least through 24 months, the suppression of inflammation by glucocorticoids may counterbalance their adverse effects on bone remodeling.