MGUS prognosis

Risk stratification of monoclonal gammopathy of uncertain significance

1. Assess patient for each of three risk factors

  • Abnormal serum free light chain ratio (SFLC)
  • Serum M protein ≥ 15 g/L
  • M protein not of IgG subtype

2. Sum the number of risk factors to determine risk category and prognosis

Number of factorsRisk cate­gory20 year pro­gression risk (%)20 year pro­gression risk ac­counti­ng for death as com­peting factor (%)
0Low52
1Low-inter­mediate2110
2High-inter­mediate3718
3High5827

This prognostic system for monoclonal gammopathy of uncertain significance (MGUS) was developed following a retrospective analysis of serum free light chain (SFLC) ratio of 1148 patients presenting between 1960 and 1994.1 Each of the three risk factors studied (abnormal SFLC, serum M protein (paraprotein) ≥ 15 g/L, non-IgG paraprotein subtype) carried a hazard ratio of ~2.5 for progression.

Patients who progressed developed the following disease entities:

  • myeloma (61%)
  • IgM-expressing lymphoma (20%)
  • primary amyloidosis (7%)
  • macroglobulinemia (7%)
  • chronic lymphocytic leukemia (3%)
  • plasmacytoma (2%)