Table 1 Demographic and laboratory characteristics of 4118 MASS-FIX positive patients, stratified by non-LC N-glycosylated (3897) and LC N-glycosylated (221) subgroups.

From: MASS-FIX for the detection of monoclonal proteins and light chain N-glycosylation in routine clinical practice: a cross-sectional study of 6315 patients

 

Total MASS-FIX Positive

No LC N-glycosylation

LC N-glycosylation

P value

Men

2476 (60)

2335 (60)

141 (64)

0.25

Age at diagnosis [median years (IQR)]

67 (59–74)

67 (59–74)

69 (59–74)

0.77

Follow-up from diagnosis [median years (IQR)]

1.5 (0.5–5.1)

1.5 (0.5–5.1)

1.6 (0.5–5.2)

0.57

Time from diagnosis to MASS-FIX [median months (IQR)]

3.5 (0.1–50.7)

3.3 (0.1–50.5)

5.0 (0.1–55.3)

0.09

Treated prior to MASS-FIX

1299 (32)

1221 (31)

78 (35)

0.22

Free light chains

 Increased FLC ratio (kappa)

1443 (39)

1333 (38)

110 (55)

<0.001

 Decreased FLC ratio (lambda)

557 (15)

536 (15)

21 (10)

0.06

 Normal FLC ratio

1681 (46)

1611 (46)

70 (35)

 

Serum protein electrophoresis

 Quantifiable M-spike

1671 (41)

1538 (39)

133 (60)

0.18(78)

MASS-FIX characteristics

 IgG isotypea

2575 (63)

2436 (63)

139 (63)

0.91

 IgA isotypea

703 (17)

685 (18)

18 (8)

<0.001

 IgM isotypea

710 (17)

655 (17)

55 (25)

0.002

 IgD/IgE isotypeb

15 (<1)

15 (<1)

0

 

 Kappa light chain restricteda

2374 (58)

2201 (56)

173 (78)

<0.001

 Lambda light chain restricteda

1886 (46)

1838 (47)

48 (22)

<0.001

 Free heavy chain

2 (<1)

2 (<1)

0

 

 Light chain only

283 (7)

272 (7)

11 (5)

0.25

Kappa free light chain

121 (43)

115 (42)

6 (55)

 

Lambda free light chain

162 (57)

157 (58)

5 (45)

 

 Monoclonal pattern

3626 (88)

3437 (88)

189 (85)

0.23

 Biclonal pattern

228 (6)

210 (5)

18 (8)

0.08

 Triclonal pattern

7 (<1)

4 (<1)

3 (1)

 
  1. Data are given as [n (%)] unless otherwise noted. IQR, interquartile range. FLC ratio was available for 3681 MASS-FIX positive patients, 3480 non-LC N-glycosylated patients, and 201 LC N-glycosylated patients. For the LC N-glycosylation subgroup, MASS-FIX categories for heavy chain isotypes, involved light chain, light chain only, and clonality are in reference to the glycosylated monoclonal protein.
  2. Bolded p values indicate statistically significant differences between non-LC N-glycosylated and LC N-glycosylated groups.
  3. aFor the MASS-FIX positive group and non-LC N-glycosylated subgroup, light chain restriction and overall heavy chain isotype are not mutually exclusive due to biclonality; for the LC N-glycosylation subgroup, overall heavy chain isotype is mutually exclusive, with the exception of two patients with biclonal patterns and LC N-glycosylation of both clones (both patients were IgM kappa and IgG kappa).
  4. bMASS-FIX is not set up to detect monoclonal IgD/IgE. Light chains detected by MASS-FIX and samples reflexed to standard, gel-based immunofixation.
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