Lupus Anticoagulant and Complement <scp>C4</scp> Consumption in Antiphospholipid Antibody Testing: Disentangling Inflammation From Autoimmunity

C4 showed the strongest association in this dataset, whereas CRP largely reflected nonspecific inflammation, especially in hospitalized men. Observed sex-associated patterns were present, with women more often showing complement consumption and men more often showing CRP elevations. These findings indicate that C4 showed a clearer analytical signal than composite definitions, while CRP should be interpreted cautiously. Prospective studies with linked clinical outcomes are needed for validation.