Differences in disease phenotype and severity in SLE across age groups

Objectives Significant differences have been reported in disease phenotype and severity of systemic lupus erythematosus (SLE) presenting in different age groups. Most indicate a more severe phenotype in juvenile-onset SLE (JSLE). There have been limited studies in older patients and no large studies looking at SLE across all age groups. Methods We assessed the effect of age of onset of SLE on the clinical phenotype by analysing data from two large UK cohorts (the UK JSLE Cohort and the UCLH SLE cohort). Results A total of 924 individuals were compared (413 JSLE, 511 adult-onset SLE). A female preponderance was present, but less pronounced at either end of the age spectrum. Arthritis was more common with advancing age (93% vs 72%, p<0.001), whereas renal disease (44% vs 33%, p=0.001), alopecia (47% vs 23%, p<0.001) and aphthous ulcerations (39% vs 26%, p=0.001) were more common in the young. Neuropsychiatric lupus was less common in mature-onset SLE (p<0.01). JSLE was associated more commonly with thrombocytopenia (21% vs 15%, p=0.01), haemolytic anaemia (20% vs 3%, p<0.001), high anti-dsDNA (71% vs 63%, p=0.009), Sm (22% vs 16%, p=0.02) and RNP (36% vs 29%, p<0.04) auto-antibodies. Leucopenia increased with advancing age (p<0.001). Mortality has been declining over recent decades. However, death rates were substantially higher than the general population. The standardized mortality ratio was 18.3 in JSLE and 3.1 in adult-onset SLE. Conclusion These data from the largest-ever direct comparison of JSLE with adult-onset SLE suggest an aggressive phenotype of disease with a worse outcome in patients with JSLE and emphasizes the importance of careful follow-up in this population.