TABLE II.

Differences between the definition of CVID ICON vs Ameratunga et al¹⁶

CVID ICON	Ameratunga et al16
The diagnosis is “definite” if all criteria are met.	The diagnosis is “probable” if all criteria are met.
“Probable” or “possible” CVID is not defined.	Both “probable” and “possible” CVID are defined; there is no “definite” CVID.
Serum IgG level must be below local/regional clinical   laboratory norms.	Serum IgG must be <5 g/L for all.
IgA or IgM must be low (IgA low preferred).	IgA or IgM may be low, but neither is required to be low.
Impaired vaccine response is required for the diagnosis.	Impaired vaccine response may be supportive of the diagnosis, but is not required.
The diagnosis may be established solely on the basis of   laboratory criteria.	Some symptom/clinical manifestation must be present for “probable” CVID.
The diagnosis is not influenced by additional laboratory   criteria.	“Probable” CVID may be established with supportive laboratory criteria (low IgG3, low   memory B cells, increased CD21, low B cells, autoantibodies) and genetic alterations   (TACI, BAFFR, MSH5, and others).
The diagnosis does not depend on histological criteria.	“Probable” CVID may be established with supportive histological criteria (granulomas,   lung or gastrointestinal disease).

ICON, International Consensus.