Systemic lupus erythematosus - diagnosis and classification of the disease in the past and in present times

The main feature of systemic lupus erythematosus (SLE) is its heterogeneity, which mainly refers to clinical presentation, the course of disease and prognosis, which can impact any organ and various immunoserological tests. As a result, prompt illness recognition and right diagnosis are extremely complicated processes based on the most recent classification standards and the doctor's clinical expertise with specific patients. In contrast, not all SLE patients are included when using classification criteria, which are based on a definition of a homogenous group by the specified, restricted number of clinical and immunoserological domains and for the purpose of conducting clinical or epidemiological investigations. Classification criteria have evolved over the last 50 years in response to new understandings and advances. This process began with the American College of Rheumatology (ACR) criteria in 1971 and continued through their updates in 1982 and 1997, followed by Systemic Lupus International Collaborating Clinics 2012 and the European League Against Rheumatism (EULAR)/ACR 2019. EULAR/ACR 2019 criteria have proven their high validity (sensitivity and specificity) in numerous studies, as well as adequate diagnostic usefulness, defined by 24 items in 10 domains, with the fulfillment of the essential precondition of antinuclear antibody positivity.