How common is APS

This is difficult to gauge as the condition is often under-recognised and undiagnosed, and few large-scale epidemiological studies have been conducted to provide prevalence data.

However, evidence from a robust study carried out in 2019: "The Epidemiology of Antiphospholipid Syndrome. A Population‐Based Study", indicates that the prevalence of APS in the population is 1 in every 2000, which means it can be classified as a rare disease.

As widespread research has yet to be carried out into the symptoms of APS, we can only base our statistics on smaller studies, but a general approximate guide which can be applied to APS is the 1 in 6 rule:

• 1 in 6 young (under 50) strokes
• 1 in 6 young (under 50) DVTs
• 1 in 6 young (under 50) heart attacks
• 1 in 6 recurrent miscarriages

In recent years, there has been a movement towards international collaboration, and researchers have now joined together to create APS ACTION – the Alliance for Clinical Trials and International Networking. The trials and collaboration will hopefully yield concrete statistics and improve treatment options for patients in the future.

APS can affect all age groups, from infancy to old age, but most patients are diagnosed when they are between 20 and 50 years old. It is more common among women – for every two men with APS, seven women are affected.