Proposal and validation of prognostic scoring systems for IgG and IgA monoclonal gammopathies of undetermined significance.
OBJECTIVE
The presenting clinico-hematologic features of 1,283 patients with IgG and IgA monoclonal gammopathies of undetermined significance (MGUS) were correlated with the frequency of evolution into multiple myeloma (MM).


METHODS
Two IgG MGUS populations were evaluated: a training sample (553 patients) and a test sample (378 patients); the IgA MGUS population consisted of 352 patients.


RESULTS
Forty-seven of the 553 training group patients and 22 of 378 test group IgG patients developed MM after a median follow-up of 6.7 and 3.6 years, respectively. Multivariate analysis showed that serum monoclonal component (MC) levels of < or =1.5 g/dL, the absence of light-chain proteinuria and normal serum polyclonal immunoglobulin levels defined a prognostically favorable subset of patients, and could be used to stratify the patients into three groups at different 10-year risk of evolution (hazard ratio, 1.0, 5.04, 11.2; P < 0.001). This scoring system was validated in the test sample. Thirty of the 352 IgA patients developed MM after a median follow-up of 4.8 years, and multivariate analysis showed that hemoglobin levels of <12.5 g/dL and reduced serum polyclonal immunoglobulin correlated with progression. A pooled statistical analysis of all of the patients confirmed the validity of Mayo Clinic risk model showing that IgA class, serum MC levels, and light-chain proteinuria are the most important variables correlated with disease progression.


CONCLUSIONS
Using simple variables, we validated a prognostic model for IgG MGUS. Among the IgA cases, the possible prognostic role of hemoglobin emerged in addition to a decrease in normal immunoglobulin levels.
Rossi
Francesca
F
UO Ematologia 1/CTMO, Fondazione Ospedale Maggiore PoMaRe, Istituto di Ricovero e Cura a Carattere Scientifico, Università degli Studi, Italy.
Petrucci
Maria Teresa
MT
Guffanti
Andrea
A
Marcheselli
Luigi
L
Rossi
Davide
D
Callea
Vincenzo
V
Vincenzo
Federico
F
De Muro
Marianna
M
Baraldi
Alessandra
A
Villani
Oreste
O
Musto
Pellegrino
P
Bacigalupo
Andrea
A
Gaidano
Gianluca
G
Avvisati
Giuseppe
G
Goldaniga
Maria
M
Depaoli
Lorenzo
L
Baldini
Luca
L
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D017098:IgA Deficiency / Q000150:complications / Q000175:diagnosis*; D017099:IgG Deficiency / Q000150:complications / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000175:diagnosis* / Q000209:etiology / Q000276:immunology / Q000401:mortality; D010265:Paraproteinemias / Q000150:complications / Q000175:diagnosis* / Q000401:mortality; D011379:Prognosis; D012107:Research Design; D016019:Survival Analysis; D055815:Young Adult