Catastrophic Antiphospholipid Syndrome (CAPS) is a rare and dangerous form of Antiphospholipid Syndrome (APS), an autoimmune disease that causes the body to make harmful antibodies that increase the risk of blood clots. In CAPS, blood clots form rapidly throughout the body, often affecting several organs at the same time. Because it can develop very quickly, CAPS is considered a life-threatening medical emergency. 1
APS itself affects the immune and clotting systems. Normally, the immune system protects the body from infections. In autoimmune diseases like APS, the immune system mistakenly attacks healthy parts of the body. In APS, the body creates antibodies that target proteins involved in blood clotting. These antibodies can make the blood more likely to clot than normal. 2
CAPS occurs in less than 1% of people with APS, but it has a much higher risk of serious complications and death than standard APS. Without fast treatment, CAPS can cause multiple organs to fail within days. 3
In CAPS, tiny blood clots form inside small blood vessels throughout the body. These clots block blood flow and reduce oxygen delivery to tissues and organs. This can damage organs very quickly.
CAPS commonly affects:
When multiple organs are damaged simultaneously, the condition can become critical very rapidly.
Doctors do not fully understand why some people develop CAPS, but research suggests that certain triggers may initiate the process in people who already have APS or antiphospholipid antibodies. 5
Common triggers include:
Sometimes CAPS develops without a clear trigger.
Researchers believe that inflammation, abnormal immune activity, and clotting problems all work together in CAPS. This can create a “clotting storm,” where the body forms widespread clots in a short period of time. 7
Symptoms usually begin suddenly and worsen quickly. Because CAPS can affect many organs, symptoms may look different from person to person.
Common symptoms include:
Because symptoms can resemble severe infections, including sepsis, severe autoimmune diseases, organ failure syndromes, or other serious medical conditions, CAPS can sometimes be difficult to diagnose quickly.
There is no single test that confirms CAPS. Doctors use a combination of symptoms, blood tests, imaging studies, and medical history.
Blood tests may look for:
Doctors may also order:
CAPS is usually diagnosed when:
Other causes are ruled out 11
CAPS treatment should begin as quickly as possible. Most patients require hospitalization, often in an intensive care unit (ICU). Treatment focuses on stopping new clots, reducing inflammation, and treating the trigger causing CAPS. 12
Common treatments include:
Some patients may receive medications such as rituximab or eculizumab if standard treatments are not enough. 13
Patients may also need oxygen, dialysis, ventilation, or cardiac support, depending on which organs are affected.
Many individuals can recover from CAPS if they start treatment early, though it might take weeks or even months. For some, there could be lasting organ damage following a severe illness, but with proper care and support, recovery is possible. 14
Even after recovery, people usually remain at risk for future blood clots. Long-term treatment often includes:
Living with CAPS or APS can be physically and emotionally difficult. Many patients experience anxiety, fatigue, fear of future clots, and challenges with daily activities. Support from doctors, family, counselors, and patient organizations can help improve quality of life.
Important ways to reduce clotting risk include:
Call 911 or seek emergency medical help right away if you have APS and experience:
References:
1. American Society of Hematology
2. National Organization for Rare Disorders (NORD)
3. Cleveland Clinic
4. Johns Hopkins Medicine
5. Hospital for Special Surgery
6. National Institutes of Health
7. Mayo Clinic Laboratories
8. American College of Rheumatology
9. NHS
10. CDC