Using the SLE-keyî Rule-Out Test in Clinical Practice

Objectives: The patient referred to a rheumatology clinic for workup of suspected Systemic Lupus Erythematosus (SLE) often presents a difficult diagnostic problem; until recently, there have been no objective tests validated to rule in or rule out SLE and the diagnosis is based on a list of criteria that may be open to interpretation. Methods: To approach this problem, a serologic rule out test for SLE was developed based on antigen microarray profiling of multiplex antibody reactivities. This SLE-key® test was developed by ImmunArray and, using stored serum samples from recognized academic centers, was validated to rule out SLE with 94% sensitivity, 75% specificity and a negative predictive value (NPV) of 93%. In clinical practice, however, patients are referred one at a time from peripheral clinical units, often with incomplete documentation. Results: We report here the usefulness of the SLE-key® test in aiding the management of a cohort of suspected SLE patients in a large clinical rheumatology practice. We compared the diagnosis and disposition of 163 referrals in whom we used the SLE-key® Rule-Out test to our typical experience with referrals before the test was available. This paper shows that the SLE-key® test provided actionable clinical information and helped us with patient management in several ways; in some patients we were able to definitively rule out a diagnosis of SLE, saving time and evaluation costs; in other patients, we were able to accelerate the diagnosis of SLE and the initiation of therapy. Conclusions: The SLE-key® Rule-Out test increased efficiency in saving undue concern, time and resources both to the patient and to the healthcare system.