Two hundred and twenty-two patients with SLE (198 women and 24 men; mean age 51 years; range 18–88) taking part in the prospective follow-up programme KLURING (a Swedish acronym for ‘Clinical LUpus Register In Northeastern Gothia’) at the Rheumatology Clinic, Linköping University Hospital, Sweden were included between September 2008 and November 2012. This corresponds to about 95% of the expected SLE cases in the catchment area of Linköping and ≥98% of all known SLE cases. The patient material was recently described in detail.35 (link) A total of 178 patients (80%) met the ACR-82 criteria,3 (link) and 44 (20%) had a clinical diagnosis of SLE based on a history of abnormal ANA titre (specified below), and at least two typical organ manifestations at the time of diagnosis (referred to as the Fries’ criteria).36
37 (link) The presence of anticardiolipin antibodies of IgG and/or IgM class detected by ELISA and/or positive lupus anticoagulant test (not classified as an immunological criterion according to ACR-82) was found in 31 of the 44 individuals (70%) in the Fries’ group.
Patients were consecutively recruited; most were prevalent cases (85%), but some (15%) had newly diagnosed SLE at the time of enrolment. Distribution of age at disease onset is demonstrated in figure 1. The median disease duration by year 2012 was 12 years (mean 13.4; range 0–49). Disease severity/organ damage was estimated using the SLICC/ACR damage index (SDI) at the end of year 2011 or from the last observation made.38 (link) Two hundred and six (93%) of the patients were Caucasians. Ninety-two (41%) of the patients were prescribed antimalarials (AM) alone, 68 (31%) other disease-modifying antirheumatic drugs±AM and 128 (58%) oral glucocorticoids. IF-ANA staining patterns, anti-ENA reactivity and dsDNA antibodies were analysed on a routine basis at the Clinical immunology laboratory, Linköping university hospital and were extracted from medical records. In many patients, IF-ANA analysis was performed at several occasions over time but discrepant staining patterns were achieved in less than 5% of these cases. Herein, IF-ANA staining pattern from the time-point most adjacent to SLE onset was used for comparisons with clinical and laboratory features.