Clusters of disease manifestations in patients with antiphospholipid syndrome demonstrated by factor analysis

The antiphospholipid syndrome (APS) is now recognized as a multi-system disease, the clinical expression of which may include various target-organs involvements. Despite the reported heterogeneity in clinical presentation of APS, the interrelations between various manifestations of the disease has not yet been studied. We evaluated the principle associations between a variety of clinical manifestations in APS patients, applying factor analysis. Two-hundred and forty-six APS patients were studied. The following disease manifestations were used for the factor analysis: recurrent fetal loss, intrauterine growth restriction (IUGR), venous and arterial thrombosis, cardiac valves thickening/dysfunction, valvular vegetations, stroke, epilepsy, migraine, arthritis, livedo reticularis, thrombocytopenia, leukopenia and autoimmune hemolytic anemia (AIHA). The results were further analysed in relation to sex and to primary APS versus APS associated with SLE. Five factors were derived, which accounted for 59.7% of the variance of the matrix. Factor 1 (which explained 18.5% of variance of the original matrix) represented the association between cardiac valves abnormalities, livedo reticularis and AIHA. Factor 2 (13.8% of variance) represented association between arthritis, thrombocytopenia and leukopenia. Factor 3 (10.3% of variance) represented an association between recurrent fetal loss and IUGR. Factor 4 (9.3% of variance) represented inverse correlation between arterial and venous thrombosis. Factor 5 (7.8% of variance) represented an association between epilepsy and migraine. Application of factor analysis revealed specific clusters of cardiac, cutaneous, hematological and neurological manifestations. Our result also point to a possible divergence of arterial and venous thrombotic tendency. Awareness of these patterns might give us a better understanding of the disease.