Background and Aims

Non-criteria Anti-phospholipid antibodies have gained great interest in recent years for their role in the Antiphospholipid Syndrome as well as for their possible value in patients negative for anti-phospholipid antibodies (aPL) of the Sydney consensus and Lupus Anticoagulant (LA).

Here we study the presence of the non-criteria aPL among patients fulfilling APS clinical manifestations. We also aim to analyze the differential clinical characteristics of isolated positive patients for non-criteria aPL.

Methods

We studied a cohort of 838 patients who met the clinical APS classification criteria obtained from the 4487 patients with suspected-APS evaluated in 2017 at the Hospital 12 de Octubre. All the patients were evaluated for Anti-PS/PT(IgG/M), IgA anti-Beta 2 glycoprotein I, aPL and LA were evaluated.

A control group of 220 age and gander match heathy donors was use for comparisons.

Results

A total of 314 patients were positive for at least one aPL, of them 137(16%) met the Sidney laboratory criteria, 50 were anti-PS/PT isolated positive and 71 were isolated positive for the IgA anti-Beta 2 glycoprotein I. Patients isolated positive for LA were 54. Inter-rater agreement between anti-PS/PT(IgG/M) and LA was moderate: Kappa index 0.51 (CI:0.44-0.57). The inclusion of non-criteria aPL identifies 42% of the patient's positives for any aPL.

Conclusions

The inclusion of non-criteria aPL may help in APS diagnosis. LA and Anti-PS/PT identify different types of patients. Although 58% of LA + were also PS/PT +, there were isolated positives for both determinations with clearly different clinical characteristics.