Despite ongoing efforts, there are still several gaps regarding lupus specificity in the Systemic Lupus International Collaborating Clinics (SLICC) network, according to a study that analyzed the recently reviewed criteria of the system. SLICC-12, the new set of criteria established in 2012 to classify systemic lupus erythematosus (SLE), was recently examined for the first time on an adult European study population.
The “Application of the 2012 systemic lupus international collaborating clinics classification criteria on a Regional Swedish systemic lupus erythematosus register” study, which was published in the Arthritis Research & Therapy journal, focused on the updated classification criteria, and compared it with previous systems. The researchers concluded that there is still an unmet need regarding the diagnosis of SLE.
“Establishing a standard definition of SLE continues to challenge lupus researchers and clinicians. We confirm that SLICC-12 has advantages with regard to diagnostic sensitivity, whereas we found the diagnostic specificity to be surprisingly low,” explained the authors in the article, which include Anna Ighe, Örjan Dahlström, Thomas Skogh and Christopher Sjöwall.
SLICC-12 has been applied to cases of confirmed SLE diagnosis in the regional SLE register, in addition to patients who were suspected to suffer from a systemic autoimmune disease, in combination with a visit to a rheumatology specialist.
Therefore, in order to be able to conduct a comparison, the researchers analyzed the cases of 243 confirmed SLE diagnosis, according to the 1982 American College of Rheumatology (ACR-82) classification criteria or the Fries diagnostic principle, which includes the presence of antinuclear antibodies (ANA) on at least one occasion in addition to involvement of at least two defined organ systems. A control group of 55 patients who could possibly suffer from systemic autoimmune disease, with presence of any SLE-related autoantibody, was also included in the study.
The research team observed that in 94% of the cases, SLICC-12 revealed diagnostic sensitivity, while ACR-97 only registered 90% of sensitivity, and the ACR-82 missed the identification of one in each five true SLE cases. On the other hand, regarding disease specificity, SLICC-12 only reached 74% accuracy. In addition, the scientists concluded that there were no substantial alterations when at least two different organs where involved as indicators of systemic disease.
SLICC-12 also failed in classification, as it misclassified more cases from the control group than either ACR-82, ACR-97 or Fries. “To accomplish increased sensitivity and specificity figures, a combination of criteria sets for clinical SLE studies should be considered,” the authors recommended in the abstract.