An evaluation of autoimmune antibody testing patterns in a Canadian health region and an evaluation of a laboratory algorithm aimed at reducing unnecessary testing

Choosing which in-hospital laboratory tests to target for intervention: a scoping review

INTRODUCTION

Some laboratory testing practices may be of low value, leading to wasted resources and potential patient harm. Our scoping review investigated factors and processes that developers report using to inform decisions about what tests to target for practice improvement.

METHODS

We searched Medline on May 30th, 2019 and June 28th, 2021 and included guidelines, recommendation statements, or empirical studies related to test ordering practices. Studies were included if they were conducted in a tertiary care setting, reported making a choice about a specific test requiring intervention, and reported at least one factor informing that choice. We extracted descriptive details, tests chosen, processes used to make the choice, and factors guiding test choice.

RESULTS

From 114 eligible studies, we identified 30 factors related to test choice including clinical value, cost, prevalence of test, quality of test, and actionability of test results. We identified nine different processes used to inform decisions regarding where to spend intervention resources.

CONCLUSIONS

Intervention developers face difficult choices when deciding where to put scarce resources intended to improve test utilization. Factors and processes identified here can be used to inform a framework to help intervention developers make choices relevant to improving testing practices.

Frequency and Clinical Utility of Antibodies to Extractable Nuclear Antigen in the Setting of a Negative Antinuclear Antibody Test

OBJECTIVE

Simultaneous antibody testing during screening for autoimmune conditions is discouraged. The incidence of positive extractable nuclear antigen (ENA) in the setting of a negative antinuclear antibody (ANA) has been reported as low. Our objective was to characterize the frequency of diagnosis of new ANA-associated rheumatic disease (AARD) in the setting of a negative ANA with a positive ENA.

METHODS

This was a 7-year retrospective study from a multicenter tertiary health network in Australia. Clinical information was sought on patients over 18 years old who had a negative ANA but positive ENA test result. Results were extracted from hospital computer systems.

RESULTS

From March 19, 2011, to July 23, 2018, ENA testing was ordered simultaneously with an ANA test on 4,248 occasions in 3,484 patients. ANA was positive in 2,520 patients (59.3%) and ENA was positive in 1,980 patients (46.6%). Among positive ANA patients, ENA was positive in 1,563 patients (62.0%). Among 1,728 negative ANA tests, ENA was positive in 417 (24.1%) (P < 0.001). A total of 328 patients with discordant ANA/ENA results had data available for further analysis, of whom 279 had no pre-established rheumatologic condition. A new AARD was diagnosed in 17 of 279 patients, yielding a positive predictive value of 6.09% (95% confidence interval 3.59-9.58).

CONCLUSION

Despite the higher-than-expected incidence of positive ENA in the setting of a negative ANA, the yield of newly diagnosed rheumatic diseases was low. Our findings support the stepwise addition of ENA requests when an ANA test result is positive and clinical suspicion of an AARD is high.

Antinuclear Antibody Testing for the Diagnosis of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune inflammatory condition that may involve multiple organ systems. Although the antinuclear antibody (ANA) test is positive in nearly every case of SLE, it is not specific for this disease and must be interpreted in the appropriate clinical context. Key features that warrant ANA testing include unexplained multisystem inflammatory disease, symmetric joint pain with inflammatory features, photosensitive rash, and cytopenias. ANA staining patterns and more specific autoantibody testing may be helpful in diagnosis of suspected SLE or ANA-associated disease. For patients with nonspecific symptoms, such as malaise and fatigue, ANA testing is of limited value.

Indications and diagnostic outcome of antineutrophil cytoplasmic antibody testing in hospital medicine: a pattern of over-screening

INTRODUCTION/OBJECTIVE

Antineutrophil cytoplasmic antibodies (ANCA) serology can aid in the diagnosis and classification of ANCA-associated vasculitides (AAV). However, it is often ordered in patients without clinical manifestations of vasculitis. In this retrospective chart review, we aim to better understand the clinical practices on ANCA testing.

METHODS

We retrospectively reviewed patients' charts for the indications and diagnostic outcomes of ANCA tests. All ANCA tests ordered at two Canadian hospitals (a community hospital and an academic tertiary hospital) between January and December 2016 were included in the study. Descriptive statistics are used.

RESULTS

A total of 302 ANCA tests were included. The majority (n = 198, 65.6%) were ordered without an indication for testing. For those patients with at least 1 clinical manifestation of AAV (n = 104), 25% were ANCA positive and 18.3% resulted in a diagnosis of AAV. In comparison, among those without a clinical manifestation of AAV (n = 198), only 1.5% were ANCA positive and none was diagnosed with AAV. All patients diagnosed with AAV had at least 1 indication for ANCA testing. The three most common clinical presentations in patients with a final diagnosis of AAV were glomerulonephritis (81.8%), pulmonary hemorrhage (45.5%), and multiple lung nodules (31.8%).

CONCLUSION

To our knowledge, this is the first study that evaluates patients with both positive and negative ANCA test results in an inpatient setting. We demonstrated a low rate of ANCA positivity and AAV diagnosis in patients without clinical manifestations of AAV. Overall, there is a high rate of ANCA testing without an indication at our academic institution. This over-testing may be curbed by strategies such as a gating policy, culture changes, and clinician education. Key Points • AAV is a clinical-pathological diagnosis, and despite the usefulness of ANCA testing, it does not confirm nor rule out AAV. • ANCA testing for the diagnosis of AAV is generally only indicated when there is a clear manifestation of AAV. • Although patients with AAV may occasionally present without classic signs and symptoms, the diagnostic utility of ANCA serology in this setting is low, and testing is more likely to result in a false-positive or false-negative test. • If clinical suspicion remains high despite negative ANCA testing, clinicians should seek consultation with a rheumatologist.

Assessment of antinuclear antibodies (ANA): National recommendations on behalf of the Croatian society of medical biochemistry and laboratory medicine

Antinuclear antibodies (ANA) represent a family of autoantibodies targeting ubiquitous cellular constituents and are a hallmark of systemic inflammatory autoimmune rheumatic diseases named connective tissue diseases (CTD). The gold standard method for ANA determination is indirect immunofluorescence (IIF) on the human laryngeal epidermoid carcinoma cell line type 2 substrate (HEp-2), but with increasing demand for ANA testing, novel methods eased for automation emerged, which allows testing by staff less experienced in this specific field of laboratory diagnostic. In 2016 The working group (WG) for laboratory diagnostics of autoimmune diseases as part of the Committee for the Scientific Professional Development of the Croatian Society of Medical Biochemistry and Laboratory Medicine (CSMBLM) published the data of a survey regarding general practice in laboratory diagnostics of autoimmune diseases in Croatia. Results indicated high diversity in the performance of autoantibody testing as well as reporting of the results and indicated the need of creating recommendations for the assessment of ANA that would help harmonize diagnostics of systemic autoimmune rheumatic diseases in Croatia. This document encompasses twenty-seven recommendations for ANA testing created concerning indications for ANA testing, preanalytical, analytical, and postanalytical issues, including rational algorithm and quality control assurance. These recommendations are based on the relevant international recommendations and guidelines for the assessment of ANA testing and relevant literature search and should help to harmonize the approach in ANA testing and clarify differences in interpretation of the results obtained using different methods of determination.

Antinuclear Antibody Testing for the Diagnosis of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune inflammatory condition that may involve multiple organ systems. Although the antinuclear antibody (ANA) test is positive in nearly every case of SLE, it is not specific for this disease and must be interpreted in the appropriate clinical context. Key features that warrant ANA testing include unexplained multisystem inflammatory disease, symmetric joint pain with inflammatory features, photosensitive rash, and cytopenias. ANA staining patterns and more specific autoantibody testing may be helpful in diagnosis of suspected SLE or ANA-associated disease. For patients with nonspecific symptoms, such as malaise and fatigue, ANA testing is of limited value.

Appropriateness of laboratory tests in the diagnosis of inflammatory rheumatic diseases among patients newly referred to rheumatologists

INTRODUCTION

Autoantibody tests are commonly ordered when screening for rheumatic diseases. Rheumatoid factor (RF) and antinuclear antibody (ANA) have low positive predictive values in general practice. Overuse of diagnostic tests can result in an increase in unnecessary referrals, patient anxiety, and further costs.

OBJECTIVE

The objective was to evaluate the utilization patterns, appropriateness, and associated costs of tests including ANA, extractable nuclear antibodies (ENA), anti-double stranded DNA (anti-dsDNA), RF, and HLA-B27 in patients referred to rheumatologists.

METHODS

A review was conducted of consecutive referrals (accepted and rejected) using university rheumatologists' practices over one year. Inappropriate investigations, and associated costs were analyzed. Tests were considered appropriate if at least one criterion for a specific disease was provided.

RESULTS

Of 638 referrals the most common reported reasons for referral were: spondyloarthropathies (SpA), rheumatoid arthritis (RA), and lupus (SLE). Prior to referral: 61% had undergone ANA testing at least once, ANA was repeated in one third; 19% had ENA and 21% had anti-dsDNA. 20% had ANA testing with no clinical indication. Half of ENA and anti-dsDNA testing was in the context of a negative ANA. RF was requested in 65% and in close to one third, there was no clinical suspicion of inflammatory arthritis.

CONCLUSION

Despite the recommendations by CRA Choosing Wisely Campaign, at least 50% of laboratory investigations, including RF, ANA, ENA, and anti-dsDNA, are inappropriately ordered. More selective ordering of the above tests would lead to marked cost reduction.

Seroconversion to antinuclear antibody negativity and its association with disease flare in patients with systemic lupus erythematosus

OBJECTIVE

To evaluate the rate of seroconversion to antinuclear-antibody negativity in patients with systemic lupus erythematosus and its association with subsequent systemic lupus erythematosus flare risk.

METHODS

Medical records of patients with systemic lupus erythematosus with positive antinuclear antibodies (titer ≥1 : 40) at diagnosis and at least one repeat antinuclear antibody test were reviewed. We determined the frequency of seroconversion to antinuclear antibody negativity among these patients and investigated whether seroconversion to antinuclear antibody negativity was associated with subsequent systemic lupus erythematosus flare risk. The seroconversion to antinuclear antibody negativity was defined as a conversion of positive antinuclear antibodies to a titer below the cut-off of 1 : 40. Systemic lupus erythematosus flare was defined as one new British Isles Lupus Assessment Group A or two new British Isles Lupus Assessment Group B domain scores. To estimate hazard ratios and 95% confidence intervals for systemic lupus erythematosus flare according to seroconversion to antinuclear antibody negativity, Cox regression analysis with adjustment for known systemic lupus erythematosus flare risk factors was performed. Kaplan-Meier analysis was used to compare flare-free survival rates between negative converters and non-converters.

RESULTS

Among the total 175 patients, seroconversion to antinuclear antibody negativity was found in 17 (9.7%) patients in a median 53.5 (range: 25.7-84.0) months. After the last antinuclear antibody tests, 53 systemic lupus erythematosus flare cases were identified during 14.3 (range: 8.2-21.7) months of follow-up. Systemic lupus erythematosus flare risk was significantly lower in patients with negatively seroconverted antinuclear antibodies (adjusted hazard ratio 0.13, 95% confidence interval 0.03-0.58, p = 0.007). Kaplan-Meier analysis showed significantly higher flare-free survival in negative converters than in non-converters (p = 0.004).

CONCLUSION

Seroconversion to antinuclear antibody negativity occurred in 9.7% of patients over 53.5 months and was associated with a lower future systemic lupus erythematosus flare risk.

Effectiveness of the use of an algorithm in the diagnostic approach of joint pain patients by primary care physicians

There is a high percentage of error in the approach of patients with joint pain by primary care physicians. An algorithm can help improve this misdiagnosis problem. Our study seeks to determine the effectiveness of an algorithm when used by primary care physicians for the diagnosis of cases of joint pain patients. A randomized clinical experiment was carried out. Primary care physicians from five cities in Colombia developed a series of clinical cases, which were presented to them through a website on their personal cell phones. Half of the doctors developed the cases using the diagnostic algorithm, and the other half developed the cases without the use of the algorithm. Main measures were proportion of correct diagnosis, number, type of laboratory and diagnostic images requested for the diagnostic approach of clinical cases. Two hundred and twenty-four primary care physicians participated. The overall proportion of cases correctly diagnosed was 37.3% higher in the intervention group; we found a greater difference in cases of spondyloarthritis (60.8%), followed by systemic lupus erythematosus with joint involvement (32.2%), rheumatoid arthritis (30.3%) and osteoarthritis (25.9%). The average number of tests requested to develop clinical cases was lower in the intervention group than in the control group, both globally and for each of the four diseases, with statistically significant differences for each of the comparisons. The diagnostic algorithm proved to be an effective tool when used by primary care physicians; the proportion of correct diagnoses increased, and the number of tests requested in the development of the cases decreased.

Frequency of repeat antinuclear antibody testing in Ontario: a population-based descriptive study

BACKGROUND

Repeat antinuclear antibody (ANA) testing may be unnecessary, potentially harmful and costly. Our aim was to assess the frequency and correlates of repeat ANA testing in Ontario.

METHODS

We performed a retrospective descriptive study identifying ANA tests performed over 2008-2015 among adults within the Ontario Laboratories Information System. Our primary outcome was any ANA test performed within 1 year of a previous ANA test. Our secondary outcome was any repeat test after a previous positive result. Repeat testing overall (regardless of who performed the previous test) and repeat testing by the same provider who performed the previous test were determined separately. We assessed correlates of repeat testing (e.g., patient and physician characteristics) and of repeat testing after a positive result using separate logistic regression models by means of generalized estimating equations to account for clustering of repeat testing within patients and within physician practices.

RESULTS

In total, 587 357 ANA tests were performed in 437 966 patients over the study period, of which 126 322 (21.5%) gave a positive result and 164 913 (28.1%) were repeat tests. Family physicians ordered 358 422 tests (61.0%), and rheumatologists ordered 65 071 tests (11.1%). Of the repeat tests, 82 332 (49.9%) were ordered within 12 months of the previous test. Among the 73 961 repeat tests ordered by the same practitioner within 12 months, the previous test result was positive for 22 657 (30.6%). A higher proportion of rheumatologists than other physicians ordered repeat tests within 12 months (36.1% v. 11.3%). The most significant correlate of potentially redundant testing was testing among patients with suspected or confirmed connective tissue disease.

INTERPRETATION

Over a quarter of ANA tests in Ontario were repeat tests; rheumatologists were most likely to order repeat testing. Our findings may be useful to inform quality-improvement initiatives related to the appropriateness of ANA testing.

Pattern of antinuclear antibody and antiextractable nuclear antigen antibody test requisitions in Riyadh

Background:

International guidelines for screening of systemic autoimmune rheumatic diseases (SARD) recommend antinuclear antibody (ANA) test as the first level test and antiextractable antigen (anti-ENA) along with anti-double-stranded DNA (anti-dsDNA) as second line tests following a reactive ANA test. This study was performed to assess adherence to international guidelines for investigation of SARD and to compare the requesting pattern of ANA and second level tests between rheumatology and nonrheumatology physicians in Riyadh.

Methodology:

This retrospective cross-sectional study comprising of 300 first time requests for investigation of SARD was performed in the immunology unit at King Khalid University Hospital (KKUH). Data were collected between April and May 2018. Information regarding the requesting physicians’ specialty and the first time requested tests (ANA, anti-dsDNA, and anti-ENA) were extracted from the electronic medical records. Reasons for requisition of tests were also recorded.

Results:

Of the total requests, 159 (53%) requests included ANA as a single first level test, whereas the rest of the requests (n = 141, 47%) included ANA test in conjunction with second level tests for the investigation of SARD. From the department of rheumatology, 14 (29.8%) initial requests were for ANA test as the only first line investigation that was significantly lower than 145 (57.3%) similar requests from the rest of the departments (P < 0.001).

Conclusion:

ANA and second level tests requests by physicians particularly among rheumatologists lacked compliance to international guidelines. The current study strongly suggests the need for strict compliance to international guidelines for screening of systemic autoimmune disorders among physicians.

Antinuclear Antibody Tests

The presence of antinuclear antibodies (ANAs), which include autoantibodies to extractable nuclear antigens (ENAs), in the sera of patients with connective tissue diseases provides useful immunologic and pathophysiologic insight into the nature of their disease. This article discusses the most commonly used diagnostic modalities for detecting and quantitating the presence of ANA: indirect immunofluorescence assay, enzyme-linked immunosorbent assay, and multiplex bead technology, which serve as useful screening tests. We also review testing for autoantibodies to ENAs, which are often helpful to confirm the diagnosis of a specific connective tissue disease.

Systemic Lupus Erythematosus, Sjögren Syndrome, and Mixed Connective Tissue Disease in Children and Adolescents

Juvenile systemic lupus erythematosus (jSLE), mixed connective tissue disease (jMCTD), and Sjögren syndrome (jSS) are systemic autoimmune and inflammatory disorders with distinct patterns of organ involvement. All are characterized by autoantibody formation, with antinuclear (ANA) and anti-double-stranded DNA common in jSLE, ANA with high-titer ribonucleoprotein antibody in jMCTD, and Sjögren syndrome A and Sjögren syndrome B antibodies + ANA in jSS. Recognition, monitoring, and management for primary care providers are discussed, focusing on the role of primary physicians in recognizing and helping maintain optimal health in children with these potentially life-threatening diseases.

Repeat Testing of Antibodies and Complements in Systemic Lupus Erythematosus: When Is It Enough?

OBJECTIVE

Patients with systemic lupus erythematosus (SLE) frequently undergo repeat testing for antibodies against extractable nuclear antigens (anti-ENA), but it is not known whether this is necessary or cost-effective. This study characterized the frequencies of changes in anti-ENA, anti-dsDNA, and complement C3 and C4 upon repeat testing.

METHODS

Chart review was done at one site of 130 patients with SLE enrolled in the 1000 Canadian Faces of Lupus prospective registry with annual antibody and complement testing. We determined the frequency of seroconversion (changes) on the next test and over the entire followup given 1 or multiple consistent results, and the cost to detect these changes.

RESULTS

Overall, 89.4% of patients had no changes in anti-ENA screening results from the first available test, 3.3% changed from negative to positive, and 7.3% from positive to negative. Following a single anti-ENA test, 3.9% of negative tests changed to positive and 4.2% of positive changed to negative on the next test. After multiple consistent tests, the frequencies of changes progressively declined. No changes from the first test were observed in anti-dsDNA, C3, and C4 in 60.8%, 83.3%, and 75.4% of patients, respectively. After 2 consistent anti-ENA tests, the cost to detect 1 change was above US$2000.

CONCLUSION

Anti-ENA results change infrequently, especially following 1 or more negative tests. The high cost and lack of evidence that changes affect management suggest that repeating anti-ENA tests routinely is unnecessary. Anti-dsDNA and complements change more frequently after an abnormal result, but less after a normal value.

Employing a results-based algorithm to reduce laboratory utilization in ACTH stimulation testing

BACKGROUND

The High Dose Adrenocorticotropic Hormone (ACTH) Stimulation Test is the gold standard to diagnose adrenal insufficiency. Normal adrenal function is defined as a peak cortisol response to pharmacologic stimulation with cosyntropin of ≥18 μg/dL. Our practice was to obtain cortisol levels at 0, 30 and 60 min after cosyntropin administration. Once a value of ≥18 μg/dL has been obtained, adrenal insufficiency is ruled out and there is little diagnostic utility in subsequent stimulated levels.

METHODS

We aimed to decrease laboratory utilization by developing a results-based algorithm in the electronic medical record (EMR). Cortisol levels were analyzed on the 0 and 60 min samples; then an EMR discern rule automatically generated an order to analyze the 30-min sample if the 60-min cortisol level was subnormal.

RESULTS

Exclusion of adrenal insufficiency was excluded using one stimulated cortisol level in 8% prior to algorithm development. After several plan-do-study-act cycles, 99% of normal tests were performed using only one stimulated cortisol level.

CONCLUSIONS

This laboratory-based algorithm resulted in reduced laboratory utilization, and aligned our practice to recommendations of the Pediatric Endocrine Society. Similar algorithms could be created for other dynamic tests to reduce unnecessary laboratory utilization.

Current practice in laboratory diagnostics of autoimmune diseases in Croatia. Survey of the Working group for laboratory diagnostics of autoimmune diseases of the Croatian Society of Medical Biochemistry and Laboratory Medicine

INTRODUCTION

With the trend of increasing incidence of autoimmune diseases, laboratories are faced with exponential growth of the requests for tests relating the diagnosis of these diseases. Unfortunately, the lack of laboratory personnel experienced in this specific discipline of laboratory diagnostic, as well as an unawareness of a method limitation often results in confusion for clinicians. The aim was to gain insight into number and type of Croatian laboratories that perform humoral diagnostics with the final goal to improve and harmonize laboratory diagnostics of autoimmune diseases in Croatia.

MATERIALS AND METHODS

In order to get insight into current laboratory practice two questionnaires, consisting of 42 questions in total, were created. Surveys were conducted using SurveyMonkey application and were sent to 88 medical biochemistry laboratories in Croatia for the first survey. Out of 33 laboratories that declared to perform diagnostic from the scope, 19 were selected for the second survey based on the tests they pleaded to perform. The survey comprised questions regarding autoantibody hallmarks of systemic autoimmune diseases while regarding organ-specific autoimmune diseases was limited to diseases of liver, gastrointestinal and nervous system.

RESULTS

Response rate was high with 80 / 88 (91%) laboratories which answered the first questionnaire, and 19 / 19 (1.0) for the second questionnaire. Obtained results of surveys indicate high heterogeneity in the performance of autoantibody testing among laboratories in Croatia.

CONCLUSIONS

Results indicate the need of creating recommendations and algorithms in order to harmonize the approach to laboratory diagnostics of autoimmune diseases in Croatia.

Choosing Wisely: The Canadian Rheumatology Association’s List of 5 Items Physicians and Patients Should Question

Objective.

To develop a list of 5 tests or treatments used in rheumatology that have evidence indicating that they may be unnecessary and thus should be reevaluated by rheumatology healthcare providers and patients.

Methods.

Using the Delphi method, a committee of 16 rheumatologists from across Canada and an allied health professional generated a list of tests, procedures, or treatments in rheumatology that may be unnecessary, nonspecific, or insensitive. Items with high content agreement and perceived relevance advanced to a survey of Canadian Rheumatology Association (CRA) members. CRA members ranked these top items based on content agreement, effect, and item ranking. A methodology subcommittee discussed the items in light of their relevance to rheumatology, potential effect on patients, and the member survey results. Five candidate items selected were then subjected to a literature review. A group of patient collaborators with rheumatic diseases also reviewed these items.

Results.

Sixty-four unique items were proposed and after 3 Delphi rounds, this list was narrowed down to 13 items. In the member-wide survey, 172 rheumatologists responded (36% of those contacted). The respondent characteristics were similar to the membership at large in terms of sex and geographical distribution. Five topics (antinuclear antibodies testing, HLA-B27 testing, bone density testing, bone scans, and bisphosphonate use) with high ratings on agreement and effect were chosen for literature review.

Conclusion.

The list of 5 items has identified starting points to promote discussion about practices that should be questioned to assist rheumatology healthcare providers in delivering high-quality care.

Clinical and serological analysis of patients with positive anticyclic citrullinated Peptide antibodies referred through a Rheumatology Central Triage System

OBJECTIVE

Anticitrullinated protein antibodies (ACPA) are a highly specific and sensitive biomarker for the diagnosis of rheumatoid arthritis (RA). Some patients who were found to have a positive ACPA test were referred to our Rheumatology Central Triage (CT; Calgary, Alberta, Canada) for assessment by a rheumatologist. The objectives of our study were to determine the clinical accuracy of ACPA in establishing a diagnosis of RA in a real-time clinical setting.

METHODS

Cases that met 3 criteria were included in the study: (1) referred to the CT over 3 calendar years (n = 20,389), (2) reason for referral was a positive ACPA test (n = 568), and (3) evaluated by a certified rheumatologist (n = 314). An administrative serological database was used to retrieve specific ACPA results.

RESULTS

Of patients referred through our CT for evaluation of a positive ACPA test, 57.6% received a diagnosis of RA; the remainder had a variety of other diagnoses, some of which might be considered early RA (9%). The predictive values of ACPA for the diagnosis of RA were increased when rheumatoid factor (RF) results were included in the analysis. When definite and possible RA were combined and the prevalence of moderate/high ACPA was compared to all other individuals, the positive and negative predictive values for moderate/high ACPA for RA were 74.3% and 68.4%, respectively.

CONCLUSION

About 58% of patients with a positive ACPA referred through a triage system for a rheumatologist opinion received a diagnosis of RA at their first visit. RF provides additional useful information to guide the diagnosis and urgency of referral.

Clinical and serological features of patients referred through a rheumatology triage system because of positive antinuclear antibodies

Background

The referral of patients with positive anti-nuclear antibody (ANA) tests has been criticized as an inappropriate use of medical resources. The utility of a positive ANA test in a central triage (CT) system was studied by determining the autoantibody profiles and clinical diagnoses of patients referred to rheumatologists through a CT system because of a positive ANA test.

Methods

Patients that met three criteria were included: (1) referred to Rheumatology CT over a three year interval; (2) reason for referral was a “positive ANA”; (3) were evaluated by a certified rheumatologist. The CT clinical database was used to obtain demographic and clinical information and a serological database was used to retrieve specific ANA and/or extractable nuclear antigen (ENA) test results. Clinical information was extracted from the consulting rheumatologist's report.

Results

15,357 patients were referred through the CT system; 643 (4.1%) of these because of a positive ANA and of these 263 (40.9%) were evaluated by a certified rheumatologist. In 63/263 (24%) of ANA positive patients, the specialist provided a diagnosis of an ANA associated rheumatic disease (AARD) while 69 (26.2%) had no evidence of any disease; 102 (38.8%) had other rheumatologic diagnoses and 29 (11%) had conditions that did not meet AARD classification criteria. Of ANA positive archived sera, 15.1% were anti-DFS70 positive and 91.2% of these did not have an AARD.

Conclusions

This is the first study to evaluate the serological and clinical features of patients referred through a CT system because of a positive ANA. The spectrum of autoantibody specificities was wide with anti-Ro52/TRIM21 being the most common autoantibody detected. Approximately 15% of referrals had only antibodies to DFS70, the vast majority of which did not have clinical evidence for an AARD. These findings provide insight into the utility of autoantibody testing in a CT system.