The diagnosis of periodic fevers is unified by undiagnosed but recurrent fever. Unfortunately the diagnosis of these disorders is hampered by their infrequency, protean features and a lack of clear criteria. Even more problematic is knowing who should be tested and for which monogenic marker?

Th cryopyrin-associated periodic syndrome (CAPS) is a rare, heterogeneous disease entity associated with NLRP3 gene mutations that leads to unregulated caspase activity and highly augmented interleukin-1 (IL-1) production.

A team of investigators gathered a interdisciplinary team of 16 international experts and utilized information from the CAPS registries, systematic literature review, expert surveys, consensus conferences to develop clinically reliable CAPS criteria.

Analyses using 284 cases and 837 controls established seven variables were significantly associated with CAPS diagnosis (p<0.001). These included:

• Raised inflammatory markers (C-reactive protein/serum amyloid A) plus ≥two of the following six CAPS-typical symptoms:
  • Urticaria-like rash,
  • Cold-triggered episodes,
  • Sensorineural hearing loss,
  • Musculoskeletal symptoms,
  • Chronic aseptic meningitis and
  • Skeletal abnormalities.

The sensitivity was 81% and specificity was 94%.  Moreover these criteria performed well regardless if the NLRP3 mutation was present or not.

These criteria should prove useful in the clinic and in clinical trials treating children or adults with CAPS.

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