Patterns of systemic lupus erythematosus expression in Europe

Objectives: To analyse the differences in disease expression of European SLE patients based on gender, age at diagnosis, and ethnicity.

Methods: A two-year, retrospective, multicentre, observational study was carried out in five countries (France, Germany, Italy, Spain and the UK). Patients' clinical manifestations including disease activity, organ involvement, organ damage and flares were analysed.

Results: Thirty-one centres enrolled 412 consecutive eligible patients (90.5% of women), with active disease, stratified by disease severity (half severe and half non-severe). Baseline characteristics included; mean (SD) age: 43.3 (13.6) years, SLE duration: 10.7 (8.0) years and age at disease diagnosis: 32.6 (13.0) years old. The mean (SD) SELENA-SLEDAI and SLICC/ACR scores were: 8.1 (6.7) and 0.82 (1.36), respectively. Over half of patients experienced flares (54.9%). The average number of annual flares was 1.01 (0.71) flares/year. In males compared to females, the renal system was more frequently active (53.8% vs 30.0%, p=0.002), the mean SLICC/ACR score was higher (1.15 vs 0.79, p=0.039) and the pulmonary system was more likely to be damaged (12.8% vs 3.8%, p=0.010). Furthermore, patients diagnosed at younger age displayed more renal system activity (young: 56.3% vs adult: 33.4% vs elder: 8.9%, p<0.001) and renal damage (25.0% vs 6.9% vs 2.2%, p=0.018) compared to the others. The annual number of flares (1.13 vs 1.05 vs 0.81 flares/year, p<0.0001), including the occurrence of severe flares (0.58 vs 0.51 vs 0.20, p<0.0001), was also higher in these patients. Conversely, greater organ damage was observed in patients diagnosed at an older age compared to the others. The mean SLICC/ACR score was higher (1.31 vs young: 0.88 and adult: 0.78, p<0.001) in patients diagnosed in the older age groups. The pulmonary (13.3% vs younger: 0% vs adult: 3.7%, p=0.030) and cardiovascular (17.8% vs younger: 0% vs adult: 2.9%, p<0.001) systems were more frequently damaged in these patients. Black African descents showed greater disease activity compared to Caucasian patients. They flared more often (77.1% vs 48.6%, p=0.001) and experienced a greater number of annual flares (1.57 vs 0.89 flares/year, p<0.0001), mainly more severe flares (0.89 vs 0.38/year, p<0.0001). They also were more likely to experience renal system damage.

Conclusion: The study showed clearly two patient subsets. The disease was the most active in Black African descents, and this phenomenon has never been described before in continental Europe. The disease was also more active in patients diagnosed at a younger or adult. Greater disease damage was observed in males and in patients diagnosed at an older age.