Repeated thromboses are the most frequent clinical manifestation of antiphospholipid syndrome (APS) in the presence of antiphospholipid antibodies (aPL). The objective of this study was to observe the prevalence and localization of thrombosis, and to investigate the importance of aPL type and level for thrombosis-related events in patients diagnosed with APS. These are the first results of patients enrolled in Serbian National Cohort Study which comprises 256 patients: 162 with primary antiphospholipid syndrome (PAPS) and 94 with APS associated with systemic lupus erythematosus (SLE). aPL analysis included detection of aCL (IgG/IgM), β₂GPI, and lupus anticoagulant. Thrombosis was diagnosed in 119 (46.5%) patients, with higher prevalence in PAPS compared with SLE patients (51.2% and 38.3%, respectively, p = 0.045). There was similar prevalence of arterial thrombosis in PAPS and SLE groups (34.6% and 34%, respectively, p = 0.932) although venous thrombosis was more frequent in PAPS (25.9% and 8.5%, respectively, p = 0.001). Thrombosis was observed in 92 (55.8%) patients who had more than one type of antibody (category I), in 13 (41.9%) patients with category IIa, in 19 (46.3%) patients with category IIb, and in 73 (44.2%) patients with category IIc ( p = 0.10). The patients with thrombosis were older than those without thrombosis (49.8 and 39.8 years, respectively, p = 0.001). Overall, older age was a risk factor for thrombosis. The prevalence of venous thrombosis was higher in the PAPS group, but with lower frequency than in literature data. Any aPL type and level is a risk factor for thrombosis.

Objective: The potential contribution of asymmetric dimethylarginine (ADMA) and high-sensitivity C reactive protein (hsCRP) to endothelial dysfunction in APS patients has not been studied in detail, until now. The study involved 105 APS patients (59 diagnosed with primary APS (PAPS) and 46 APS associated with systemic lupus erythematosus (SAPS)) who were compared to 40 controls. Endothelial dysfunction was assessed by measurement of flow-mediated dilatation (FMD) and glyceryl trinitrate dilatation (NMD) of the brachial artery. ADMA (micromol/L) was analyzed by ELISA. Results: FMD in patients with APS was significantly lower than that of the controls (p < 0.001), with no difference between the PAPS and the SAPS groups. ADMA and hsCRP concentrations were significantly higher in the patient cohort than in the control group (p < 0.001, p = 0.006, respectively), as was the case with the SAPS group as compared to the PAPS group (p < 0.001, p = 0.022, respectively). FMD impairment correlated to ADMA (ρ 0.472, p < 0.001) and to hsCRP (ρ 0.181, p = 0.033). In the regression model, the ADMA concentration confirmed the strength of its association (B 0.518, SE 0.183, Wald 8.041, p = 0.005, Exp(B) 1.679, 95% CI 1.174–2.402) to FMD impairment. The synergistic probability model of ADMA and hsCRP caused FMD impairment when the positivity of β2GPIIgG was added. ADMA may be used as a simple and low-cost tool for verifying the presence of endothelial dysfunction in APS patients. According to the results of the study, we could presume that hsCRP, together with aPL, has a preparatory effect on the endothelium in causing endothelial dysfunction.

Introduction: Antiphospholipid syndrome (APS) is linked to an in-creased risk of cardiovascular diseases due to the interplay between traditional risk factors and antibody-induced endothelial damage. Limited data exist on the level of physical activity (PA) in APS patients. This study aimed to analyze PA domains in Serbian APS patients and their association with atherosclerosis progression. Materials and Methods: Fifty-one APS patients (29 with primary APS (PAPS), mean age 44.0 ± 11.5, and 22 with APS/SLE (sAPS), mean age 48.4 ± 11.7) completed the long form of the International Physical Activity Questionnaire (IPAQ), translated into Serbian. PA was categorized into leisure time, domestic activities, work-related, and transport-related domains, and classified as low, moderate, or high. Carotid Doppler ultrasound scans were performed to detect atherosclerotic plaques. Results: The total PA in a PAPS group ranged from 0 to 26.880 MET-minutes/week and in sAPS from 0 to 19.200. Work-related and domestic activities had the highest scores, while leisure time PA was lowest. Most patients had low (37.3%) or moderate (43.1%) PA levels, with only 19.6% in the high PA category. No significant PA differences were found between PAPS and sAPS patients. However, PAPS patients were more likely to have high PA (27.6% vs. 9.1%), though not significantly. Patients with lower PA scores had a higher prevalence of carotid plaques, particularly for vigorous (p=0.001) and total PA (p=0.002). Conclusion: Younger Serbian APS patients predominantly exhibit low or moderate PA, especially during leisure time. Low PA strongly correlates with atherosclerosis progression, underscoring the need to promote physical activity in this population.