Associations between biological markers and haematological manifestations in patients with systemic lupus erythematosus.

BACKGROUND

Haematological conditions are part of the EULAR/ACR 2019 diagnostic criteria for systemic lupus erythematosus (SLE). They consist of 4 cytopenias (haemolytic anaemia, leucopenia, lymphopenia and thrombocytopenia) which may appear at diagnosis and/or during follow-up. The simultaneous involvement of these cytopenias in the clinical and immunological management of patients with SLE is poorly understood. Therefore, the purpose of this study is to determine the overall relationships between them, as well as the individual associations of each.

METHODS

Two hundred and two Caucasian patients with adult-onset SLE were studied. Medical records were reviewed from January 2005 to December 2024 and clinical and laboratory variables were collected at diagnosis and during follow-up.

RESULTS

Eighty patients (39.6 %) had some form of haematological manifestation. Overall, haematological manifestations showed positive associations with C3 and C4 hypocomplementemia, anti-Ro/SSA antibodies and sex ratio (female/male), as well as a negative association with lupus nephritis. When analyzing the 4 cytopenias individually, surprising results were found. C3 and/or C4 hypocomplementemia was simultaneously associated with haemolytic anaemia, leucopenia and lymphopenia. Anti-double-stranded DNA antibodies were associated with thrombocytopenia (OR = 5.269, P = 0.026; multivariate analysis). Leucopenia was positively associated with anti-Ro/SSA antibodies (OR = 8.888, P = 0.003; multivariate analysis), and negatively associated with lupus nephritis (OR = 0.184, P = 0.007; univariate analysis) and lupus anticoagulant (OR = 0.132, P = 0.039; multivariate analysis). Finally, lymphopenia was associated with sex ratio.

CONCLUSIONS

Therefore, haematological conditions in patients with SLE present specific features that could represent a distinctive subtype of SLE.