Background/Purpose: SLE diagnosis and classification can be challenging. The low incidence of SLE limits primary care physician experience with the disease, but the impact of early diagnosis & treatment on long term outcome makes a compelling case for early referral for rheumatology consultation upon suspicion of SLE. ANA testing, currently used for screening of suspected SLE patients, is characterized by high false positive rates increasing the likelihood of misplaced suspicion of SLE. The diagnostic workup for referred patients is long, costly and often inconclusive, with a high rate of misdiagnosis. Misdiagnosis can lead to use of medications with potential side effects and even irreversible damage as well as significant psychological distress, anxiety and/or depression for the patient as well as family members. Access to a simple serological test to rule out a diagnosis of SLE would contribute to all the stakeholders involved in lupus diagnosis; patients, physicians and payers. The SLE-key^® test may represent such a test. The SLE-key^® Rule Out test was developed and validated to rule out a diagnosis of SLE with 94% sensitivity and 75% specificity (Putterman C, J Imm Meth 2016). The goal of the current study was to monitor the clinical and financial impact of the test in clinical practice.

Methods: 245 patients were referred from five busy, geographically independent rheumatology clinics. Serum samples and clinical information were collected from both patient and physician with informed consent in a HIPAA compliant manner. Sera along with clinical data were sent to Immunarray’s CLIA-certified laboratory, Veracis (Richmond, VA) for SLE-key® RuleOut testing and evaluation using ImmunArray’s iCHIP® platform.

Results: The SLE-key^® test effectively ruled out a diagnosis of SLE in >54% of patients referred, including patients with personal or family history of autoimmune disease. Over 300 ANA tests were recorded for this cohort and almost 90% of the patients had at least one positive ANA test result sometime during their clinical evaluation. 55% of these were Ruled Out using the SLE-key test. These included patients referred with multiple symptoms including joint pain, mouth sores and rashes in addition to their ANA positive test. Clinical data from at least one visit post SLE-key^® testing was available for 98/134 patients where SLE was ruled out. Clinical diagnosis in 5 (5%) of these cases was SLE. For an additional 8 (8%) cases, SLE remained under consideration as part of the differential diagnosis.

Conclusion: The SLE-key® test can be used to enhance the efficiency of triage of patients referred into the rheumatology practice. More than half of patients referred with symptoms leading to a suspicion of systemic autoimmune rheumatic disease (SARD) may have a diagnosis of SLE quickly eliminated from the diagnostic algorithm. Thus, the SLE-key Rule Out test, can significantly reduce unnecessary costs and diagnostic time and increase the efficiency of healthcare delivery.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/sle-key-ruleout-testing-in-support-of-patient-triage-in-the-clinical-rheumatology-setting/