The concordance of serial ANA tests in an Australian tertiary hospital pathology laboratory

Serological intermolecular epitope spreading in a patient with primary Sjögren's syndrome

Sjögren's syndrome (SS) is one of the prototypic systemic autoimmune diseases characterised by autoreactive T and B cells, sicca symptoms and various extraglandular manifestations. SS is characterised by autoantibodies (anti-Ro52/tripartite motif containing-21 [TRIM21], anti-Ro60 and anti-La) that are important diagnostic biomarkers. Patients have typically stable serostatus; that is, patients who are positive for one or more of these autoantibodies tend to remain thus and vice versa. We describe a rare instance where a woman in her 50s was diagnosed with primary SS and developed new autoantibodies subsequently through serological epitope spreading. She demonstrated primarily glandular features only and clinical stability despite serological evolution. In this case report, we discuss the significance of this molecular feature and the clinical implications for our understanding of autoimmunity.

Inter-rater reliability assessment for the new-born screening quality assurance

Introduction

To ensure the quality of the new-born screening (NBS), our laboratory reviewed the analytical procedure to detect subjective steps that may represent a risk to the patient. Two subjective activities were identified in the extra-analytical phases: the classification of dried blood spots (DBS) according to their quality and the assignment of haemoglobin patterns. To keep these activities under control, inter-rater studies were implemented. This study aimed to evaluate the inter-rater reliability and the effectiveness of the measures taken to improve the agreement between observers, to assure NBS results’ quality.

Materials and methods

Dried blood spots specimens were used for the inter-rater studies. Ten studies were performed to assess DBS quality classification, and four to assess the assignment of haemoglobin patterns. Krippendorff’s alpha test was used to estimate inter-rater reliability. Causes were investigated when alpha values were below 0.80.

Results

For both activities, the reliability obtained in the first studies was inadequate. After investigation, we detected that the criterion to classify a DBS as scant was not consolidated, and also a lack of consensus on whether or not to report Bart’s haemoglobin depending on its percentage. Alpha estimates became higher once the training was reinforced and a consensus about the appropriate criteria to be applied was reached.

Conclusion

Inter-rater reliability assessment helped us to ensure the quality of subjective activities that could add variability to NBS results. Furthermore, the evolution of the alpha value over time allowed us to verify the effectiveness of the measures adopted.

Longitudinal Tracking of Extractable Nuclear Antigen (ENA) Antibodies in a Quaternary Hospital Laboratory Cohort Reveals Dynamic Antibody Profiles

BACKGROUND

Antiextractable nuclear antigens (anti-ENAs) are regarded as diagnostic tests with no established value for serial monitoring. We therefore sought to establish the stability over time of anti-ENAs in a large diagnostic immunopathology laboratory.

METHODS

A retrospective review of all patients who had a serial anti-ENA ordered at the Westmead Hospital (Sydney, Australia) was performed over 24 months. Anti-ENA characterization was performed using line immunoassay, and historical data were available from 2013 onward. The earliest available densitometry readings were compared with the latest available to examine for a change in quantitation or qualitative (serostatus) result (from negative to positive, and vice versa). Medical records were examined for clinical correlations.

RESULTS

A total of 283 patients (24.1%) had serial testing of anti-ENA in the audit period, with each patient having an average of 3.9 ± 2.9 tests each. Most patients were diagnosed with systemic lupus erythematosus or primary Sjögren's syndrome. About 25% and 58% of patients had a qualitative and quantitative change, respectively, in at least 1 anti-ENA in the study period. Changes in anti-ENA levels correlated with erythrocyte sedimentation rate and disease activity. Increasing duration between serial tests increased the probability of observing a change in anti-ENA levels.

CONCLUSION

Certain anti-ENAs are dynamic autoantibodies that may have significance for monitoring disease activity. Laboratories may consider reporting quantitative results. Further disease- and autoantibody-specific studies are required to determine the clinical significance of changes in anti-ENAs.

Factors associated with the antinuclear antibody (ANA) titer of systemic autoimmune rheumatic diseases in ANA-positive patients after treatment: a retrospective study

Antinuclear antibodies (ANAs) are a serological hallmark of systemic autoimmune rheumatic diseases (SARDs); however, few studies have investigated their post-treatment levels. The mechanism by which ANA titers are upregulated in SARDs remains unclear. We assessed factors associated with the ANA titer after treatment. In this retrospective study, we analyzed the clinical database of Zhongshan Hospital, Medical College of Xiamen. Demographic data and baseline and 12-month post-treatment ANA titers were collected. Bivariate and multivariate analyses were performed to determine the factors associated with the ANA titer. This study identified 31,923 patients who underwent ANA assay for SARDs screening, and a total of 1043 patients were included in the study. Approximately 16% of the patients showed a decrease in the serological ANA titer. Younger patients (< 20) were 3 × more likely to experience such a decrease (P = 0.005) compared to older patients (≥ 60 years). Having a baseline ANA titer > 1:10,000 was associated with an increase likelihood of a decrease in the serological ANA titer compared with baseline ANA titer 1:10,000, 1:3200 and 1:1000 (P < 0.001). We found that a decrease in the serum ANA titer at 12 months after treatment for SARDs is associated with age and ANA baseline titers.

Identification of a unique anti-Ro60 subset with restricted serological and molecular profiles

Anti-Ro60 is one of the most common and clinically important serum autoantibodies that has a number of diagnostic and predictive capabilities. Most diagnostic laboratories report this simply as a qualitative positive/negative result. The objective of this study was to examine the clinical and serological relevance of a novel subset of anti-Ro60 in patients who display low levels of anti-Ro60 (anti-Ro60low ). We retrospectively identified anti-Ro60 sera during a 12-month period at a major immunopathology diagnostic laboratory in Australia. These all were anti-Ro60-precipitin-positive on the diagnostic gold standard counter-immuno-electrophoresis (CIEP). Lineblot immunoassay was used to stratify patients into either anti-Ro60low or anti-Ro60high subsets. We compared the medical and laboratory parameters associated with each group. Enzyme-linked immunosorbent assay (ELISA) and mass spectrometry techniques were used to analyse the serological and molecular basis behind the two subsets. Anti-Ro60low patients displayed less serological activity than anti-Ro60high patients with less intermolecular spreading, hypergammaglobulinaemia and less tendency to undergo anti-Ro60 isotype-switching than anti-Ro60high patients. Mass spectrometric typing of the anti-Ro60low subset showed restricted variable heavy chain subfamily usage and amino acid point mutations. This subset also displayed clinical relevance, being present in a number of patients with systemic autoimmune rheumatic diseases (SARD). We identify a novel anti-Ro60low patient subset that is distinct from anti-Ro60high patients serologically and molecularly. It is not clear whether they arise from common or separate origins; however, they probably have different developmental pathways to account for the stark difference in immunological maturity. We hence demonstrate significance to anti-Ro60low and justify accurate detection in the diagnostic laboratory.

Utility of repeated antinuclear antibody tests: a retrospective database study

BACKGROUND

Anti-nuclear antibody (ANA) testing is frequently used as a diagnostic or screening test in patients with inflammatory or musculoskeletal symptoms. The value of repeat testing is unclear. We sought to evaluate the frequency, utility, and cost of repeat ANA testing. The main objective was to assess the positive predictive value of a repeat ANA test for the diagnosis of rheumatological conditions associated with ANA.

METHODS

In this retrospective cohort study, we analysed data from a single, multisite tertiary health network in Australia across a 7-year period. ANA and other autoimmune test results were obtained from the hospital pathology system with a positive ANA titre cutoff set at 1:160. Clinical information was sourced from clinical information systems on any patient who had a change in ANA result from negative to positive on repeat testing. The cost of repeated ANA testing was calculated using the Australian Government Medicare Benefits Schedule.

FINDINGS

From March 19, 2011, to July 23, 2018, a total of 36 715 ANA tests were done in 28 840 patients at a total cost of US$675 029 (2018 equivalent). 14 058 (38·3%) of these ANA tests were positive. 7875 (21·4%) of the ordered tests were repeats in 4887 (16·9%) of the patients, among whom 2683 (54·9%) had initially negative tests, and 2204 (45·1%) had initially positive tests. 511 (19·0%) of the 2683 patients with initially negative tests had a positive result on at least one repeat test, with a median time to first positive result of 1·74 years (IQR 0·54-3·60). A change from negative to positive ANA was associated with a new diagnosis in only five (1·1%) of the 451 patients with clinical information available and no previous diagnosis of an ANA-associated rheumatological condition, yielding a positive predictive value of 1·1% (95% CI 0·4-2·7).

INTERPRETATION

Repeat ANA testing after a negative result has low utility and results in high cost.

FUNDING

Monash Health.

Laboratory Test Utilization and Repeat Testing for Inpatients of Age 80 and Over in Australia: A Retrospective Observational Study

Introduction

Repeat laboratory testing is often necessary in hospitals. However, frequent blood draws can be harmful to older patients. The objective of this study was to identify the most frequently ordered laboratory tests and repeat testing rates for these tests among older inpatients.

Methods

A retrospective observational study of inpatients of age 80 years and over in 4 public hospitals in New South Wales, Australia, was conducted between 2008 and 2013. Proportions of laboratory tests and proportions of repeated tests among the most frequently used tests were reported.

Results

There were 42739 patients with 108003 admissions (56.2% women; 43.2% of ages 80–84). Of these admissions, 95.9% had a laboratory test, with 3012577 tests recorded. Five tests accounted for 62% of all tests and were present in 98.5% of admissions: electrolytes urea and creatinine (EUC; 18% of all tests ordered), complete blood count (CBC; 16.7%), calcium magnesium phosphate (CaMgPhos; 10.2%), liver function test (LFT; 9.0%), and C-reactive protein (CRP; 8.0%). Proportions of repeat tests for this group performed outside recommended minimum repeat intervals were 10.3% EUC, 8.9% CBC, 41.5% CRP, 68.2% CaMgPhos, and 65.2% LFT tests. An exponential increase in repeat testing for all 5 tests was observed around 24 h after a previous test.

Conclusion

Compliance with guidelines on repeat testing intervals among older patients is variable. A better understanding of the underlying reasons for repeat testing would allow targeting of interventions, including decision support, to improve laboratory use for older inpatients.