Catastrophic APS: Can You Clinch the Diagnosis?

May 14, 2014

In CAPS, the most severe form of antiphospholipid syndrome, thromboses emerge widely and rapidly--clearly an urgent situation. Update your diagnostic skills in this quick two-part quiz.

Catastrophic APS (CAPS) is the most severe form of antiphospholipid syndrome, in which thromboses develop rapidly in multiple organs, usually associated with microthrombosis. Because defining appropriate treatment is urgent, while multiple other conditions such as sepsis and hemolytic-uremic syndrome (HUS) may show similar clinical features, early suspicion is crucial.

Clinically significant antiphospholipid  antibodiy positivity is an important diagnostic step; however, multiple factors can impede the timely diagnosis.

(For a detailed discussion of CAPS diagnosis, including algorithms, see Catastrophic antiphospholipid syndrome: how to diagnose a rare but highly fatal disease.)

Which of the following are true regarding “clinically significant aPL profile”? (You may choose more than one.)

1.   Because transient aPL positivity is common during infections, it is important to demonstrate two successive positive aPL results within one month.
2.   A positive lupus anticoagulant  (LA) test is a better predictor of aPL-related events compared to aCL and a β2 GPI ELISA.
3.   An LA test reading taken from a patient on anticoagulants can be falsely positive.
4.   At higher titers, the specificity of aCL and a β2 GPI ELISA tests for aPL-related clinical events decreases.
5.   IgG aCL and a β2 GPI ELISA are generally more commonly associated with clinical events compared with IgM isotype.

Click here for the correct responses about antibody testing for CAPS.

Or you can choose to answer further questions about CAPS diagnosis.

1.    False. Because transient aPL positivity is common during infections, documentation of two positive aPL tests at least 12 weeks apart is crucial for diagnostic purposes.
2.    True.
3.    True.
4.    False. The specificity of aCL and β2 GPI ELISA tests for aPL-related clinical events increases at higher titers.
5.    True:  IgG aCL and a β2 GPI ELISA are generally more commonly associated with clinical events compared with IgM isotype.

Click here to answer other questions about diagnosing CAPS.

Which of the following are true regarding CAPS diagnosis? (You may choose more than one.)

1.   CAPS can commonly overlap with other thrombotic microangiopathic conditions, e.g. thrombotic thrombocytopenic purpura (TTP), hemolytic-uremic syndrome (HUS), and HELLP syndrome (hemolysis with elevated liver enzymes and low platelet count).
2.     Previous APS diagnosis and/or history of persistent clinically significant aPL positivity without history of aPL-related clinical events is of great importance for diagnosis.
3.    Two or more organ thromboses developing in less than a week is the cornerstone of Definite CAPS.
4.    Unless the patient fulfills the Definite or Probable CAPS Classification Criteria, there is no reason to suspect CAPS.
5.   Based on the thrombotic storm concept, several comparable disorders (including CAPS) with an extreme prothrombotic presentation may possess a similar underlying pathophysiologic process representing an extreme response to an initial prothrombotic stimulus.

Click here for the correct responses about CAPS diagnosis.

1.   True.

2.   True.

3.   False.  Based on the preliminary classification criteria, “Definite CAPS” is defined as thromboses developing in three or more organs in less than a week, microthrombosis in at least one organ, and persistent aPL positivity. One of the definitions of “Probable CAPS” is thromboses developing in two organs in less than a week, microthrombosis in at least one organ, and persistent aPL positivity.

4.   False.   aPL-positive patients presenting with severe thrombotic, hemorrhagic, and/or microangiopathic manifestations but who do not fulfill the “Definite” or “Probable” CAPS constitute a “CAPS-like” category who should be monitored closely for the development of CAPS, and whose treatment may need to be just as intensive as that for CAPS.

True. 

Here's that citation again, for further information: Catastrophic antiphospholipid syndrome: how to diagnose a rare but highly fatal disease.

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