Determining risk factors for developing systemic lupus erythematosus in patients with discoid lupus erythematosus.

Up to 28% of patients with discoid lupus erythematosus (DLE) are susceptible to developing systemic lupus erythematosus (SLE). To better characterize patients with DLE who have a higher potential of developing SLE, we reviewed studies contrasting, firstly, DLE-only patients (i.e. patients with DLE without SLE) and SLE patients with DLE (i.e. patients who are diagnosed with SLE and DLE simultaneously, and patients with SLE who later develop DLE), and secondly, DLE-only patients and patients with DLE who progress to SLE. These studies have commonly identified various clinical and laboratory indicators, such as widespread DLE lesions, arthralgias/arthritis, nail changes, anaemia, leucopenia, high erythrocyte sedimentation rates (ESRs) and high titres of antinuclear antibodies (ANAs), which are associated with progression to SLE in patients with DLE, and SLE patients with DLE. Limitations of these studies include inadequate follow-up time, small numbers of patients with DLE converting to SLE, outdated criteria for SLE diagnosis and retrospective study designs. However, because of the risk of SLE development in patients with DLE, complete skin examinations, joint assessments and laboratory tests including ANA, ESR and full blood counts should be performed regularly for patients with DLE. A prospective study following patients with DLE who do or do not develop SLE is currently underway through the Cutaneous Lupus Registry at the University of Texas Southwestern Medical Center. It will seek to identify clinical features and biomarkers that improve our assessment of risk of systemic spread in these patients.