Table 3:

Selected models that classify SMM based on risk of progression to MM

	Criteria	Median TTP (months)
PETHEMA criteria [15]
High-risk	Two risk factors are met   (1) Immunoparesis   (2) ≥ 95% aberrant plasma cells of all plasma cells by flow cytometry	23
Intermediate	One risk factor is met	73
Low	No risk factors	Not reached
SWOG criteria [20]
High-risk	Two out of three risk factors are met   (1) Involved SFLC > 25 mg/dL   (2) M-Protein ≥ 3 g/dL   (3) GEP > −0.26	Median 6; 2-year TTP 66.7%
Intermediate	One risk factor is met	Median not reached; 2-year TTP 21.9%
Low	No risk factors	Median not reached; 2-year TTP 3.4%
MAYO 2008 criteria [16]
High-risk	Three out of three risk factors are met   (1) Bone marrow plasma cell % ≥ 10%   (2) M-protein ≥ 3 g/dL   (3) I:u sFLC ratio > 8	23
Intermediate	Two out of three risk factors are met	45
Low	One out of three risk factors are met	110
IMF 2019 criteria [17]
High-risk	Two out of three risk factors are met   (1) Bone marrow plasma cell % ≥ 20%   (2) M-protein > 2 g/dL   (3) I:u sFLC ratio > 20	30
Intermediate	One out of three risk factors are met	68
Low	No risk factors	110
MAYO 2018 criteria with FISH [17]
High-risk	Two out of three risk factors are met   (1) Bone marrow plasma cell % ≥ 20%   (2) High-risk FISH   (3) I:u sFLC ratio > 20	23.6
Intermediate	One out of three risk factors are met	83.1
Low	No risk factors	Not reached

FISH=fluorescence in situ hybridization