Aim  To compare a subgroup of patients with borderline systemic lupus erythematosus (SLE) with those with classic lupus in order to determine whether the former subset is a separate entity or a forerunner to SLE.

Methods  A retrospective survey was undertaken of a database containing the clinical information of a total of 71 patients in an Abu Dhabi hospital setting over a 12-year period. Data of interest were criterial and noncriterial features of SLE together with relevant laboratory tests.

Results  Fifty-six patients had SLE and 15 were considered to have borderline SLE as they satisfied less than four criteria of classification. Age and female sex distribution were no different in the two subgroups, but the disease duration was shorter in patients with borderline lupus. The occurrence of arthropathy (nonerosive), serositis, thrombocytopenia, hemolytic anemia, and malar eruption was common to both subgroups. Patients with borderline SLE lacked other mucocutaneous manifestations of lupus and major organ disease involvement. A number of other clinical features were also observed in the latter subgroup, including antiphospholipid (APL) syndrome. In addition, patients with borderline SLE expressed a multiple autoantibody profile, but had lower titers of antinuclear factor (ANF) and anti-double-stranded DNA (anti-dsDNA) antibodies than those with classic SLE. None progressed to full-blown SLE after a mean period of follow-up of 21.2 months.

Conclusions  In our patients, borderline SLE was milder than classic lupus, yet shared a wide spectrum of noncriterial features and also produced clinical subsets. The clinical heterogeneity and multiple antibody profile may suggest that borderline SLE is a forerunner to SLE rather than a separate entity. A regular and longer period of follow-up is required, however, to ultimately determine the fate of these patients.