Sudanese and Swedish patients with systemic lupus erythematosus: immunological and clinical comparisons

Abstract

Objective SLE is known to have an aggressive phenotype in black populations, but data from African cohorts are largely lacking. We therefore compared immunological and clinical profiles between Sudanese and Swedish patients using similar tools. Methods Consecutive SLE patients from Sudan (n = 115) and Sweden (n = 340) and from 106 Sudanese and 318 Swedish age- and sex-matched controls were included. All patients fulfilled the 1982 ACR classification criteria for SLE. Ten ANA-associated specificities and C1q-binding immune complexes (CICs) were measured. Cut-offs were established based on Sudanese and Swedish controls, respectively. Disease activity was measured with a modified SLEDAI and organ damage with the SLICC Damage Index. In a nested case–control design, Swedish and Sudanese patients were matched for age and disease duration. Results Females constituted 95.6% and 88.1% of Sudanese and Swedish patients, respectively (P = 0.02), with younger age at inclusion (33 vs 47.7 years; P < 0.0001) and shorter disease duration (5 vs 14 years; P < 0.0001) among Sudanese patients. Anti-Sm antibodies were more frequent in Sudanese patients, whereas anti-dsDNA, anti-histone and CICs were higher in Swedish patients. In the matched analyses, there was a trend for higher SLEDAI among Swedes. However, Sudanese patients had more damage, solely attributed to high frequencies of cranial/peripheral neuropathy and diabetes. Conclusion While anti-Sm is more common in Sudan than in Sweden, the opposite is found for anti-dsDNA. Sudanese patients had higher damage scores, mainly because of neuropathy and diabetes. Sudanese patients were younger, with a shorter SLE duration, possibly indicating a more severe disease course with impact on survival rates.

High IgA antiphospholipid autoantibodies in healthy Sudanese explain the increased prevalence among Sudanese compared to Swedish systemic lupus erythematosus patients

“…In agreement with our previous publication, Sudanese patients had a higher female preponderance and shorter disease duration compared to Swedish patients. 23 In the cohorts matched for age and disease duration, the occurrence of thrombosis or fetal loss did not differ between Sudanese and Swedish patients ( Table 1 ).…”

“… 22 A detailed description of cohorts was specified in our previous publication. 23 Clinical comparisons were first performed between the full cohorts. Due to the highly significant difference in age and disease duration, where Swedish patients were older with longer SLE duration, comparisons were also performed between nested cohorts matched for age and disease duration, including 88 Sudanese and 88 Swedish patients, in agreement with our previous study.…”

“…Due to the highly significant difference in age and disease duration, where Swedish patients were older with longer SLE duration, comparisons were also performed between nested cohorts matched for age and disease duration, including 88 Sudanese and 88 Swedish patients, in agreement with our previous study. 23 Clinical information including APS-related events was obtained from patients’ hospital records. These included a history of thrombotic events (venous: deep venous thrombosis and pulmonary embolism; and arterial: cerebrovascular accidents, myocardial infarction and peripheral tissue loss as described in the SLICC Damage Index (SDI)), 24 obstetric events (early and late miscarriage, intrauterine fetal demise (IUFD) and stillbirths) and cardiovascular (CVS) events as defined by the SDI.…”

Accumulation of antinuclear associated antibodies in circulating immune complexes is more prominent in SLE patients from Sudan than Sweden

“…Interestingly, we found that Sudanese SLE patients have higher IgA anti-phospholipid antibodies compared to Swedes, but this difference disappeared after adjustment to national controls, as levels were higher also among Sudanese than Swedish healthy subjects 23 . Optimally, IC levels as well as levels of autoantibodies in IC, should in the same way be related to national controls before comparison between patient groups from different geographical regions 17 .…”

“…Possible technical limitations in our study is the co-purification of anti-C1q antibodies which bind to the collagenous part of C1q, and that IC already covered by activated complement might bind poorly or not at all to the C1q-coated beads. Serum ANA investigations had been performed previously 17 and quantification of ANA www.nature.com/scientificreports/ in IC was performed later with different reagent batches. For practical reasons, eluted IC had been stored frozen at − 70 °C and not quantified immediately upon IC purification, as performed previously 18 .…”