A study of the influence of ethnicity on serology and clinical features in lupus

Objective: The objective of this study was to review the links between ethnicity, serology and clinical expression in systemic lupus erythematosus (SLE) in a single cohort that was followed over a 36-year period.

Patients and methods: Patients with SLE treated at the University College London Hospitals (UCLHs) between January 1978 and December 2013 formed the cohort. We assessed the demographic, clinical and serological data. Standard methods were used for laboratory testing. The Student t test and Mann-Whitney U test were used for the continuous variables; the Fisher's exact test was used for the categorical variables.

Results: We studied 624 SLE patients: There were 571 women (91.5%), with a mean age at diagnosis of 29.0 ± 6.5 years; and 53 men (8.5%), with a mean age at diagnosis of 29.4 ± 15.3 years. Ethnically, 369 of the patients were European, 100 were Afro-Caribbean, 77 were East Asian, 56 were South Asian and 21 were of mixed ethnicity. The East Asian patients developed the disease at a younger age than the other ethnic groups (p < 0.0001). The Afro-Caribbean patients were less frequently associated with the presence of rash and photosensitivity, and the non-European patients were more likely to have alopecia and renal involvement. The South Asian patients were significantly associated with musculoskeletal and neurological involvement, serositis, Sicca syndrome and hematological features. The Afro-Caribbean patients had the highest prevalence of anti-Smith, anti-RNP, anti-Ro and anti-La antibodies. Anti-IgG anticardiolipin (aCL) antibodies were significantly associated with the non-East Asian groups; and hypocomplementemia was common in the East Asians. Rash, alopecia, mouth ulcers, serositis, neurological, joint and renal involvement were significantly associated with the presence of anti-Smith and anti-RNP antibodies in the Afro-Caribbean group. We also observed an association of joint involvement and the presence of anti-Ro and anti-La antibodies in this group.

Conclusions: The East Asian patients developed their SLE disease at a younger age than the other ethnic groups. Cutaneous involvement was more frequent in those who were not Afro-Caribbean. Serositis, joint and neurological involvement were more frequently diagnosed in the South Asian patients. Anti-ENA antibodies were frequently associated with the Afro-Caribbean patients.