Epidemiology of Antiphospholipid Syndrome in the General Population

Purpose of Review

The epidemiology of antiphospholipid syndrome (APS) is poorly understood. Here, we review the current understanding of the epidemiology of antiphospholipid syndrome in the general population and the frequency of antiphospholipid antibodies in the general population in patients with obstetric morbidity, arterial events, and venous thromboembolism.

Recent Findings

There have been few population-based studies that estimated the prevalence and incidence of APS. The estimated incidence and prevalence among most these studies ranged between 1 and 2 cases per 100,000 and 40 and 50 cases per 100,000 respectively. The prevalence of antiphospholipid antibodies in patients with obstetric morbidity was 6–9%, while in arterial events and venous thromboembolism is 9–10%. However, this data remains limited. Mortality of patients with APS is 50–80% higher than the general population.

Summary

The epidemiology of APS has been difficult to elucidate. Population-based studies patients with diverse age, racial, and ethnic backgrounds are needed.

Diagnosis and treatment of antiphospholipid syndrome in childhood: A review

The antiphospholipid syndrome (APS) is a multisystem autoimmune disease characterized by recurrent fetal loss and thromboembolic events associated with the presence of elevated titres of antiphospholipid antibodies (aPL). The purpose of this review is to summarize what is currently known about the diagnosis and treatment of pediatric APS, to highlight key differences between APS presenting in adults versus children throughout, and to identify areas where future research is needed.

Recurrent status epilepticus in posterior reversible encephalopathy syndrome as initial feature of pediatric lupus: A newly diagnosed case and literature review

INTRODUCTION

Posterior reversible encephalopathy syndrome (PRES) is a recently described clinico-neuroradiological syndrome with several predisposing conditions. Systemic lupus erythematosus (SLE), beginning in 15-20% in childhood, is considered as a potential underlying etiology of PRES. In children, status epilepticus (SE) rarely complicates PRES, and exceptionally occurs in SLE.

METHODS

We report on an illustrative case of PRES complicating pediatric lupus revealed by recurrent SE, and we further review through a Pubmed search the previously reported cases of pediatric SLE, PRES and SE.

RESULTS

We describe the case of a 12-year old girl who presented with recurrent status epilepticus associated to high blood pressure and renal involvement. Brain imaging showed classical aspects of PRES. Immunological tests including antinuclear, anti-DNA, and anticardiolipin antibodies were positive. The diagnosis of SLE was established. The Pubmed search identified a total number of 9 children with SE in SLE, and 26 with PRES, including our patient.

CONCLUSIONS

We discussed the clinical and paraclinical features of PRES in SLE with epilepsy, their underlying pathophysiological aspects, and their management challenges. PRES should be considered in initial recurrent SE in children, justifying a battery of tests comprising immunological testing. Anticardiolipin antibodies seem to play a crucial role in epilepsy, PRES and renal involvement in pediatric SLE. Further studies are needed to clarify whether PRES should be considered one of the neuropsychiatric manifestations of SLE or a consequence of active disease in other organ systems or its treatment.

Pediatric antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a multisystem autoimmune condition characterized by vascular thromboses associated with persistently positive antiphospholipid antibodies. There is currently a paucity of data (incidence, prevalence, thrombosis risk, and effective treatment) in pediatric APS. The purpose of this report is to review the current literature on APS in children and neonates, identify the gaps in current knowledge, and suggest avenues for studies to fill those gaps.

Antiphospholipid antibodies in haemophilia patients with severe bleeding tendency: cause, consequence or a consequential cause?

The prevalence, cause and the impact of antiphospholipid antibodies (APAs) on the clinical severity in haemophilia patients is poorly studied. We studied 72 severe seronegative (negative for HIV, HBsAg, HCV) haemophilia patients for the presence of four common APAs. Twenty-six (36.1%) were positive for any one of the APAs studied of which eight were positive only for anticardiolipin antibodies, three for beta2 glycoprotein (beta2GP1), four for prothrombin (PT) and six for anti annexin antibodies. Remaining six patients showed multi-specific antibodies. Further, clinically severe haemophilia patients (n = 37) showed higher prevalence of APAs as compared with the clinically milder group (n = 35) suggesting that these antibodies do not contribute in alleviating the clinical severity in haemophilia patients as has been observed with other inherited thrombophilia markers. The study of in vitro thrombin generation showed a higher endogenous thrombin potential (ETP) i.e. almost normal, in case of beta2GP1-positive patients as compared with patients with other types of APAs. High prevalence of APAs in clinically severe haemophilia patients may be a consequence of continuing tissue damage in the clinically severe group; as in India, clotting factor concentrates cannot be used ad lib because of financial constraints. Higher thrombin-generating potential in case of patients positive for beta2GP1 did not seem to have any impact on the clinical severity of haemophilia patients.

Familial lupus and antiphospholipid syndrome

The occurrence of systemic lupus erythematosus (SLE) in several members of a family has spurred intense efforts to identify susceptibility genes predisposing to the disease. As a result, a number of candidate association genes in different ethnic groups have been identified, and some genes have been linked to specific lupus manifestations. Particularly where familial disease occurs in childhood, and especially when it occurs prior to puberty, complement deficiencies and other immunologic defects should be explored. Evidence of other forms of autoimmunity, including autoimmune thyroiditis and antiphospholipid syndrome (APS), is common in families with SLE. Familial APS is uncommon in the absence of other thrombophilic defects, but occasionally is seen with apparent autosomal dominant inheritance. Thus far, no firm gene associations have been identified for APS, in part because of the rarity of multiplex families to study. A search for other familial causes of thrombotic disease should be performed when APS occurs in more than one family member.

Antiphospholipid antibodies in pediatric systemic lupus erythematosus and the antiphospholipid syndrome

The antiphospholipid syndrome (APS) is recognized increasingly as the most common acquired hypercoagulation state of autoimmune etiology and may occur as an isolated clinical entity (primary APS) or in association with an underlying systemic disease, particularly systemic lupus erythematosus (SLE). The major differences between pediatric and adult APS include absence of common acquired risk factors for thrombosis, absence of pregnancy-related morbidity, increased incidence of infection-induced antibodies, differences in cut-off values for determination of aPL and specific factors regarding long-term therapy in children. APS in children has been largely reported in patients with arterial or venous thromboses and less frequently in association with neurological or hematological manifestations. The presence of aPL in pediatric SLE can modify the disease expression and may be an important predictor of the development of irreversible organ damage. Two recently established international registries of neonates and children with APS provide a good opportunity to conduct large, prospective studies on the clinical significance of aPL and long-term outcome of pediatric APS.

Pediatric antiphospholipid syndrome

APS is rare in the pediatric age, but it represents an interesting phenomenon because most of the known "second hit" risk factors such as atherosclerosis, smoking, hypertension, contraceptive hormonal treatment, and pregnancy are not present in childhood. This could also be the reason for the prevalence of some clinical manifestations rather than others in PAPS. On the other hand, the increased frequency of infectious processes in the childhood age is likely responsible for the relatively high prevalence of non-pathogenic and transient aPL. Such points raise the problem of a different diagnosis or monitoring approach in pediatric APS. Of particular interest is the special entity of neonatal APS, which represents an in vivo model of acquired autoimmune disease, in which transplacentally acquired aPL cause thrombosis in the newborn. International registries for pediatric and neonatal APS are currently in place; epidemiologic, clinical, and laboratory re-search will help to shed light on all the still obscure aspects of this fascinating but rare disorder in the very young. Finally, treatment is less aggressive overall in pediatric APS, given the reluctance to anticoagulate children over the long term. Studies on the outcome of pediatric APS and the relative risks of prolonged anticoagulation in children are necessary to determine the type and duration of anticoagulation therapy.

Antiphospholipid antibodies in pediatrics

Antiphospholipid antibody syndrome has been associated with vascular thrombosis, thrombocytopenia, hemolytic anemia, livedo reticularis, neurologic disorders, and recurrent fetal loss. The diagnosis of antiphospholipid syndrome is given in the presence of an elevated anticardiolipin antibody lupus anticoagulant in addition to a thrombotic event. Antiphospholipid antibodies are responsible for a majority of thrombotic events in children. These antibodies can present as a primary syndrome or secondary to other diseases, such as systemic lupus erythematosus. Anticoagulation therapy with heparin and low-dose aspirin is the recommended treatment in pediatric patients.

Anticardiolipin antibody in vascular parkinsonism

Vascular parkinsonism (VP) is characterized by predominantly lower body involvement with gait impairment and postural instability, often without tremor, and by relative levodopa unresponsiveness. Neuroimaging studies demonstrate multiple infarcts or ischemic changes in periventricular white matter. Anticardiolipin antibodies (ACLA) are associated with hypercoagulable states and increased stroke risk. Review of our Movement Disorders Clinic records identified 44 individuals with a diagnosis of VP. ACLA have been obtained in 22 of these patients (mean age, 78.3 years; mean Mini-Mental Status Exam score, 25.8). Gait disturbance was the initial clinical feature in 82% of the patients, and levodopa responsiveness was present in 18% of those treated. In 9 of the 22 (40.9%), ACLA immunoglobulin G was positive. No significant differences in clinical features or risk factors (hypertension, diabetes, coronary artery disease, and clinical stroke) were evident between ACLA+ and ACLA- groups. Since the presence of ACLA in individuals with stroke is usually treated by full-scale anticoagulation with warfarin, our findings raise the question whether such treatment should also be used in persons with VP who are ACLA positive.

Which antiphospholipid antibody tests are most useful?

Despite an active international effort to improve diagnosis and treatment of the antiphospholipid syndrome (Hughes syndrome), there remain problems of lack of standardization and lack of prospective and multivariate epidemiologic analysis which restrict the diagnostic and predictive ability of commercially available tests. Nevertheless, current published series provide some data from which strategic approaches can be used to maximize the efficiency and usefulness of available tests. For further updates on new research and developments of interest to physicians and patients with this syndrome, the following web sites may prove helpful: www.slrapls.org, www.hematology.org, www.acforum.org, www.americanheart.org, www.rarediseases.org, www.aarda.org, and www.lupus.org.