Baseline characteristics
| . | Total cohort (n = 487), (%)/median (range) . | FLC-MS negative (n = 112) . | FLC-MS positive (n = 375) . | P value . |
|---|---|---|---|---|
| Male | 291 (59.6%) | 55 (49.1%) | 236 (62.9%) | .009 |
| Age, y | 67 (36-88) | 65 (40-88) | 67 (36-86) | .62 |
| Detectable M-protein by SPEP/IFE | ||||
| None | 126 (26%) | 44 (39.3%) | 82 (21.9%) | |
| Immunofixation only | 122 (25%) | 19 (17.0%) | 103 (27.5%) | |
| SPEP, g/L, median (range) | 239 (49.0%); 8 g/L (1-45) | 49 (43.8%) 8 g/L (2-31) | 190 (50.7%) 8 g/L (1-45 g/L) | .907 |
| M-protein type | ||||
| A | 70 (14.3%) | 10 (8.9%) | 60 (16%) | .06 |
| D | 3 (0.6%) | 0 (0%) | 3 (0.8%) | |
| G | 163 (33.4%) | 41 (36.6%) | 122 (32.5%) | .422 |
| M | 13 (2.7%) | 2 (1.8%) | 11 (2.9%) | .509 |
| LC | 111 (22.7%) | 15 (13.4%) | 96 (25.6%) | .007 |
| Serum light chain type | ||||
| Kappa | 89 (18.2%) | 35 (31.3%) | 55 (14.6%) | |
| Lambda | 396 (81.1%) | 76 (67.9%) | 319 (85.1%) | ≤.0001 |
| Involved light chain, mg/L | 197 (11.6-15 900) | 145 (11.8-2 211) | 208 (11.6-15 900) | .065 |
| dFLC, mg/L | 177.7 (0-15 898) | 125 (0-2203) | 186 (2.1-15 898) | .061 |
| Organ involvement | ||||
| Renal | 349 (71.5%) | 83 (74.1%) | 266 (70.9%) | .513 |
| Creatinine, μmol/L | 94 (27-777) | 104 (33-609) | 91 (27-777) | .243 |
| eGFR, mL/min per 1.73 m2 | 67 (15 to >90) | 61.5 (15 to >90) | 69 (15 to >90) | .017 |
| 24 h urinary protein, g/24 h | 3.1 (0.1-31.6) | 3.4 (0.1-19.6) | 3.1 (0.1-31.6) | .581 |
| Heart | 290 (59.4%) | 61 (54.5%) | 229 (61.1%) | .212 |
| NTProBNP, pg/ml | 1548 (12-44 611) | 1841 (12-34 082) | 1522 (34-44 611) | .121 |
| Bilirubin, mg/dL | 5 (2-61) | 5 (2-25) | 6 (2-61) | .246 |
| Alkaline phosphatase, U/L | 85 (26-1 035) | 138 (39-734) | 82 (26-1 035) | .195 |
| LV septum, mm | 13 (6-22) | 12 (7-21) | 13 (8-22) | .032 |
| LVEF, % | 60% (11-80) | 59 (11-77) | 60 (16-80) | .278 |
| Cardiac disease stage European Modification of Mayo 2004 | ||||
| 1 | 99 (20.3%) | 29 (25.9%) | 72 (19.2%) | .125 |
| 2 | 178 (36.5%) | 30 (26.8%) | 146 (38.9%) | .019 |
| 3A | 167 (34.2%) | 41 (36.6%) | 126 (33.6%) | .556 |
| 3B | 39 (8%) | 11 (9.8%) | 28 (7.4%) | .420 |
| Missing | 4 (0.8%) | 1 (0.9%) | 3 (0.8%) | .924 |
| Cardiac disease stage Mayo 2012 | ||||
| 1 | 71 (14.5%) | 24 (21.4%) | 47 (11.7%) | .019 |
| 2 | 123 (25.2%) | 26 (23.2%) | 97 (25.8%) | .571 |
| 3 | 138 (28.3%) | 25 (22.3%) | 113 (20.1%) | .107 |
| 4 | 116 (23.8%) | 26 (23.2%) | 90 (24%) | .864 |
| Missing | 39 (8.0%) | 11 (9.8%) | 28 (7.5%) | .420 |
| Other organs | ||||
| Liver | 50 (10.2%) | 19 (17.0%) | 31 (8.3%) | .008 |
| Peripheral neuropathy | 29 (5.9%) | 6 (5.4%) | 23 (6.1%) | .761 |
| Autonomic neuropathy | 29 (5.9%) | 4 (3.6%) | 25 (6.7%) | .224 |
| Soft tissue | 80 (16.4%) | 14 (12.5%) | 66 (17.6%) | .201 |
| GI | 15 (3.1%) | 1 (0.8%) | 14 (0.4%) | .127 |
| Other | 4 (0.8%) | 0 | 4 (0.01%) | .272 |
| Number of organs involved | ||||
| 1 | 231 (47.3%) | 56 (50%) | 175 (46.7%) | .535 |
| 2 | 170 (34.8%) | 39 (34.8%) | 131 (34.9%) | .983 |
| 3 | 71 (14.5%) | 15 (13.4%) | 56 (14.9%) | .685 |
| 4 | 15 (3.1%) | 2 (1.7%) | 13 (3.5%) | .366 |
| . | Total cohort (n = 487), (%)/median (range) . | FLC-MS negative (n = 112) . | FLC-MS positive (n = 375) . | P value . |
|---|---|---|---|---|
| Male | 291 (59.6%) | 55 (49.1%) | 236 (62.9%) | .009 |
| Age, y | 67 (36-88) | 65 (40-88) | 67 (36-86) | .62 |
| Detectable M-protein by SPEP/IFE | ||||
| None | 126 (26%) | 44 (39.3%) | 82 (21.9%) | |
| Immunofixation only | 122 (25%) | 19 (17.0%) | 103 (27.5%) | |
| SPEP, g/L, median (range) | 239 (49.0%); 8 g/L (1-45) | 49 (43.8%) 8 g/L (2-31) | 190 (50.7%) 8 g/L (1-45 g/L) | .907 |
| M-protein type | ||||
| A | 70 (14.3%) | 10 (8.9%) | 60 (16%) | .06 |
| D | 3 (0.6%) | 0 (0%) | 3 (0.8%) | |
| G | 163 (33.4%) | 41 (36.6%) | 122 (32.5%) | .422 |
| M | 13 (2.7%) | 2 (1.8%) | 11 (2.9%) | .509 |
| LC | 111 (22.7%) | 15 (13.4%) | 96 (25.6%) | .007 |
| Serum light chain type | ||||
| Kappa | 89 (18.2%) | 35 (31.3%) | 55 (14.6%) | |
| Lambda | 396 (81.1%) | 76 (67.9%) | 319 (85.1%) | ≤.0001 |
| Involved light chain, mg/L | 197 (11.6-15 900) | 145 (11.8-2 211) | 208 (11.6-15 900) | .065 |
| dFLC, mg/L | 177.7 (0-15 898) | 125 (0-2203) | 186 (2.1-15 898) | .061 |
| Organ involvement | ||||
| Renal | 349 (71.5%) | 83 (74.1%) | 266 (70.9%) | .513 |
| Creatinine, μmol/L | 94 (27-777) | 104 (33-609) | 91 (27-777) | .243 |
| eGFR, mL/min per 1.73 m2 | 67 (15 to >90) | 61.5 (15 to >90) | 69 (15 to >90) | .017 |
| 24 h urinary protein, g/24 h | 3.1 (0.1-31.6) | 3.4 (0.1-19.6) | 3.1 (0.1-31.6) | .581 |
| Heart | 290 (59.4%) | 61 (54.5%) | 229 (61.1%) | .212 |
| NTProBNP, pg/ml | 1548 (12-44 611) | 1841 (12-34 082) | 1522 (34-44 611) | .121 |
| Bilirubin, mg/dL | 5 (2-61) | 5 (2-25) | 6 (2-61) | .246 |
| Alkaline phosphatase, U/L | 85 (26-1 035) | 138 (39-734) | 82 (26-1 035) | .195 |
| LV septum, mm | 13 (6-22) | 12 (7-21) | 13 (8-22) | .032 |
| LVEF, % | 60% (11-80) | 59 (11-77) | 60 (16-80) | .278 |
| Cardiac disease stage European Modification of Mayo 2004 | ||||
| 1 | 99 (20.3%) | 29 (25.9%) | 72 (19.2%) | .125 |
| 2 | 178 (36.5%) | 30 (26.8%) | 146 (38.9%) | .019 |
| 3A | 167 (34.2%) | 41 (36.6%) | 126 (33.6%) | .556 |
| 3B | 39 (8%) | 11 (9.8%) | 28 (7.4%) | .420 |
| Missing | 4 (0.8%) | 1 (0.9%) | 3 (0.8%) | .924 |
| Cardiac disease stage Mayo 2012 | ||||
| 1 | 71 (14.5%) | 24 (21.4%) | 47 (11.7%) | .019 |
| 2 | 123 (25.2%) | 26 (23.2%) | 97 (25.8%) | .571 |
| 3 | 138 (28.3%) | 25 (22.3%) | 113 (20.1%) | .107 |
| 4 | 116 (23.8%) | 26 (23.2%) | 90 (24%) | .864 |
| Missing | 39 (8.0%) | 11 (9.8%) | 28 (7.5%) | .420 |
| Other organs | ||||
| Liver | 50 (10.2%) | 19 (17.0%) | 31 (8.3%) | .008 |
| Peripheral neuropathy | 29 (5.9%) | 6 (5.4%) | 23 (6.1%) | .761 |
| Autonomic neuropathy | 29 (5.9%) | 4 (3.6%) | 25 (6.7%) | .224 |
| Soft tissue | 80 (16.4%) | 14 (12.5%) | 66 (17.6%) | .201 |
| GI | 15 (3.1%) | 1 (0.8%) | 14 (0.4%) | .127 |
| Other | 4 (0.8%) | 0 | 4 (0.01%) | .272 |
| Number of organs involved | ||||
| 1 | 231 (47.3%) | 56 (50%) | 175 (46.7%) | .535 |
| 2 | 170 (34.8%) | 39 (34.8%) | 131 (34.9%) | .983 |
| 3 | 71 (14.5%) | 15 (13.4%) | 56 (14.9%) | .685 |
| 4 | 15 (3.1%) | 2 (1.7%) | 13 (3.5%) | .366 |
Significant P values are in bold type. GI, gastrointestinal; LV, left ventricular; LVEF, left ventricular ejection fraction; SPEP, serum protein electrophoresis.