Diagnosis and Classification of Systemic Lupus Erythematosus

Systemic lupus erythematosus is a complex systemic, immune-mediated multi-organ disease without a single diagnostic test. The diagnosis is made by the recognition of patterns of symptoms and signs combined with a variety of radiographic, pathologic, biochemical, and immunologic findings. However, this can result in significant heterogeneity in the spectrum of disease. This heterogeneity can threaten the validity and reliability of SLE research findings. Classification criteria are used to identify more homogeneous groups of patients for inclusion into SLE research studies. In this chapter, we discuss the development of the 2019 EULAR/ACR classification criteria for SLE. We highlight many insights gained about the current thinking around the construct of SLE and implications for SLE diagnosis.