Similarities and differences between younger and older disease onset patients with newly diagnosed systemic lupus erythematosus

Objectives: Several studies show that age at onset has an impact on the clinical-serological presentation, comorbidities and disease course of patients with systemic lupus erythematosus (SLE). We evaluated whether, in patients with recent onset SLE, the age at onset correlates with clinical-serological manifestations and with comorbidities. Methods: We analysed 171 patients with a SLE diagnosis obtained within 12 months of diagnosis enrolled in the Early Lupus project. Based on the age of onset of the first disease symptom, they were stratified into 2 groups: early onset (18-45 years) and late onset (>45 years). The analysis was replicated by stratifying patients based on age at diagnosis (fulfillment of ACR classification criteria). Each comparison was made at baseline and at 36 months of follow-up. Results: Baseline: patients with late onset displayed comorbidities (hypertension, dyslipidemia and osteoporosis) more frequently than early onset group. 11.4% of late onset patients had a malignancy in medical history, not recorded in the early onset cohort. The two groups differed neither in organ involvement (domain BILAG) nor in disease activity (ECLAM). Patients with early onset showed a disease with signs of higher serologic activity (higher frequency of anti-dsDNA positivity and lower mean C3 and C4 levels) and had malar rash more frequently than the late onset group (36.2% vs. 18.2%, p=0.042). Similar results were obtained by stratifying patients by age of diagnosis (18-45 years and >45 years), except for the higher frequency of discoid rash in the group with age at diagnosis >45 years (18% vs. 6.6%, p=0.045). 36 months: the 2 groups of patients independently of the stratification applied did not differ in the accumulation of damage, but showed a different pattern of 8 organ involvement. Musculoskeletal involvement was more frequent both in the late onset group (18.6% vs. 7.3%, p=0.043) and in the group with age at diagnosis >45 years (20.4% vs. 5.9%, p=0.009) compared to their counterparts, while renal involvement was more frequent in the group with age at diagnosis 18-45 years (21.4% vs. 6.1%, p=0.03).A sub analysis at 36 months on patients without hypertension and osteoporosis at enrollment showed that patients with older age at onset had a higher frequency of these comorbidities, compared to their counterparts. Conclusions: In our cohort, younger disease SLE onset seems to correlate with a more active immunological profile, while late onset with a higher incidence of comorbidities.