Table 2. Serum Protein Markers Associated With Progression: Cross-sectional Analysis.
| Serum Protein Marker | MGUS | Light-Chain MGUSa | ||||||
|---|---|---|---|---|---|---|---|---|
| Without Progression, No. (%) of Controls (n = 281) | Progression to Multiple Myeloma (n = 159) | Without Progression (n = 217) | Progression to Light-Chain Multiple Myeloma (n = 28) | |||||
| Case, No. (%) | OR (95% CI) | Control, No. (%) | Case, No. (%) | OR (95% CI) | ||||
| Unadjusted | Adjusted | Unadjusted | Adjustedb | |||||
| Immunoglobulin isotype | ||||||||
| IgG | 216 (76.9) | 109 (68.6) | 1 [Reference] | 1 [Reference] | NA | NA | NA | NA |
| IgA | 47 (16.7) | 45 (28.3) | 1.90 (1.2-3.0) | 1.80 (1.0-3.1) | NA | NA | NA | NA |
| Biclonal | 18 (6.4) | 5 (3.1) | 0.55 (0.2-1.5) | 0.49 (0.1-1.6) | NA | NA | NA | NA |
| M spike concentration | ||||||||
| <15 g/L | 178 (96) | 88 (55.3) | 1 [Reference] | 1 [Reference] | NA | NA | NA | NA |
| ≥15 g/L | 8 (4) | 62 (39.0) | 15.68 (7.2-34.2) | 23.50 (8.9-61.9) | NA | NA | NA | NA |
| Serum FLC ratio | ||||||||
| 0.26-1.65 | 185 (65.8) | 37 (23.3) | 1 [Reference] | 1 [Reference] | NA | NA | NA | NA |
| 0.10-0.26 or >1.65 to 10 | 86 (30.6) | 57 (35.8) | 3.31 (2.0-5.4) | 3.45 (1.9-6.7) | 205 (94.5)c | 7 (25.0)c | 1 [Reference]c | 1 [Reference]c |
| <0.10 to >10 | 10 (3.6) | 65 (40.9) | 32.5 (15.3-69.0) | 46.4 (18.4-117.2) | 12 (5.5) | 21 (75.0) | 51.3 (18.2-144.1) | 44.0 (14.2-136.3) |
| Immunoparesisd | ||||||||
| 0 | 211 (75.1) | 64 (40.2) | 1 [Reference] | 1 [Reference] | 190 (87.6) | 13 (46.4) | 1 [Reference] | 1 [Reference] |
| 1 | 45 (16.0) | 45 (28.3) | 3.30 (2.0-5.4) | 3.01 (1.7-5.5) | 22 (10.1) | 5 (17.8) | 3.32 (1.1-10.2) | 3.98 (1.1-14.8) |
| 2 | 7 (2.5) | 45 (28.3) | 21.2 (9.1-49.3) | 19.1 (7.5-48.3) | 5 (2.3) | 10 (35.7) | 23.2 (8.7-98.2) | 48.6 (9.5-248.2) |
Abbreviations: FLC, free light chain (κ:λ); M spike, monoclonal spike; MGUS, monoclonal gammopathy of undetermined significance; NA, not applicable; OR, odds ratio.
SI conversion: To convert M spike to grams per deciliters, divide by 10.0.
Models for light-chain–secreting multiple myeloma and light-chain MGUS cases were not adjusted for race/ethnicity owing to small numbers of light-chain multiple myeloma cases for nonwhite persons. Analysis was performed in SAS, version 9.4 (SAS Institute).
ORs and 95% CIs are adjusted for sex, age at most proximal blood sample obtainment (continuous), race/ethnicity (non-Hispanic white, non-Hispanic black, and other [Hispanic, Asian, and Pacific Islander]), calendar year of most proximal blood sample obtainment (1995-1998, 1999-2002, and 2003-2006), and study center (coded as Upper Midwest [Wisconsin and Minnesota], West/South [Colorado, Hawaii, Missouri, Utah, and Alabama], and East [Georgetown, Detroit, and Pittsburgh]).
FLC ratio is 0.1 to 10 with no exclusion.
Immunoparesis is the number of uninvolved immunoglobulins (IgG, IgA, or IgM) below the lower level of normal.