Mono-organic versus multi-organic involvement in primary antiphospholipid syndrome

The prevalence of mono-organic and multi-organic involvement during long-term follow-up in patients with primary antiphospholipid syndrome (pAPS) was investigated. We studied 60 pAPS patients followed up at least 5 years. Patients with associated systemic lupus erythematosus were excluded. All patients received oral anticoagulant therapy. A diagnosis of mono-organic involvement was considered when one organ was affected exclusively, and multi-organic involvement was considered when two or more organs became affected during follow-up. Average age at diagnosis was 32.9 +/- 12.4 years, 40 subjects were female and 20 male, and mean disease evolution totaled 11.5 +/- 4.5 years. The mean number of clinical events was 3.75 +/- 1.87. Among patients, immunoglobulin G anticardiolipin (IgM aCL) titers totaled 50 +/- 40.3 IgG phospholipid units, and IgM aCL titers totaled 47.3 +/- 35.4 IgM phospholipid units. The most frequent clinical manifestations at study onset were deep venous thrombosis, stroke, pulmonary thromboembolism, fetal loss, and pre-eclampsia. At the beginning of follow-up, 46 patients had mono-organic involvement and 14 had multi-organic involvement (P = 0.0001). In contrast, at the end of the study, only 8 patients still had mono-organic involvement, leading to deep venous thrombosis (n = 3), stroke (n = 3), and retinal thrombosis (n = 2) (P = 0.0001). Kaplan-Meier analysis showed that the probability of remaining with mono-organic involvement decreased throughout the cumulative years, especially during the first 3. The hazard risk ratio for developing multi-organic involvement was 1.47 patients per year. In conclusion, PAPS is a chronic disorder with unpredictable clinical course and multi-organic involvement, especially during the first years. The conversion to multi-organic involvement supports the concept that pAPS is a systemic autoimmune disease.