Risk factors for progression from discoid lupus erythematosus (DLE) to severe systemic lupus erythematosus (SLE) include age younger than 25 years at DLE diagnosis, phototype V to VI, and antinuclear antibody (ANA) titers of at least 1:320, according to results of a retrospective registry-based cohort study published in Journal of the American Academy of Dermatology.
The researchers sought to identify the risk factors and generate a predicting score of progression to severe SLE — defined as requiring hospitalization and specific treatment — among patients with isolated DLE or SLE associated with mild biological abnormalities.
Lupus erythematosus is an autoimmune disorder that may present as a limited skin disease (ie, cutaneous lupus erythematosus [CLE]) or as a systemic disease ranging from biological abnormalities and mild symptoms to a potentially life-threatening illness with multiorgan involvement (ie, severe SLE). Among patients with CLE, DLE is the most frequently reported subtype, accounting for approximately 80% of all cases.
The study included patients with DLE whose data were identified from 3 dermatology departments and 2 internal medicine departments of French university hospitals between January 1997 and April 2021.
DLE with mild biological SLE was defined by the presence of at least 10 points using the 2019 American College of Rheumatology/European Alliance of Associations for Rheumatology (ACR/EULAR) classification criteria, with DLE being the only clinical feature associated with the presence of biological abnormalities, such as leucopenia, decreased C3 and/or C4 levels, and specific autoantibodies, with no specific treatments.
Severe SLE was defined as the occurrence of at least 1 of the following features: SLE fever, serositis, lupus nephritis, neuropsychiatric manifestation, autoimmune hemolysis, or autoimmune thrombocytopenia, along with the need for a specific treatment with systemic corticosteroids of greater than 0.5 mg/kg and/or an immunosuppressant agent and/or hospitalization related to SLE defining a severe flare.
Patients were enrolled in the study if they had DLE with pathologic confirmation, with isolated DLE or mild biological SLE at diagnosis using the 2019 ACR/EULAR SLE classification criteria. The starting point for measuring the duration of progression to severe SLE was the date of the DLE diagnosis. Patients who developed features of severe SLE at 2 months or later following a diagnosis of DLE were referred to as DLE-severe SLE, who were then compared with those with DLE with or without mild biological SLE and did not develop features of severe SLE after at least 4 years of follow-up.
A total of 30 participants with DLE-severe SLE and 134 who did have severe SLE were included in the analysis.
According to multivariable analysis, age younger than 25 years at DLE diagnosis (odds ratio [OR], 2.8; 95% CI, 1.1-7.0; P =.0243; 1 point), phototype V to VI (OR, 2.7; 95% CI, 1.1-7.0; P =.0364; 1 point), and ANA titers of at least 1:320 (OR, 15.0; 95% CI, 3.3-67.3; P <.0001; 5 points) were all chosen to generate the score. Among 54 participants with a score of 0 at baseline, none progressed to severe SLE; a score of 6 or more was associated with a risk of approximately 40%.
Study limitations included its retrospective design and the small sample size. In most cases, baseline DLE activity using the Cutaneous Lupus Erythematosus Disease Area and Severity Index was not available. In addition, no validated definition of severe SLE was included.
The study authors noted that patients with DLE with a score of at least 6 may require closer monitoring, especially with urinalysis. “This score should be validated in an external prospective cohort to confirm these preliminary data,” they concluded.
Fredeau L, Courvoisier DS, Aitmehdi R, et al; EMSED study group. Risk factors of progression from discoid lupus to severe systemic lupus erythematosus: a registry-based cohort study of 164 patients. J Am Acad Dermatol. Published online September 22, 2022. doi:10.1016/j.jaad.2022.09.028