Table 2 Performance (sensitivity and specificity analysis) of the involved FLC ratio cut-points for progression to active multiple myeloma or amyloidosis, and for high-risk smoldering multiple myeloma stratification, at interval time-points.

From: Comparison of two free light chain assays: performance of the involved free light chain ratio and implications for diagnosis of multiple myeloma

 

n (%)

12 months, % (95% CI)

24 months, % (95% CI)

60 months, % (95% CI)

iFLCr cut-points for progression to active multiple myeloma or amyloidosis, n = 284

Freelite cut-pointsa

N (%) of subjects who progressed

 

35 (13.3%)

65 (24.7%)

107 (40.7%)

iFLCr ≥ 100

30 (11.4%)

   

 Sens

 

25.7 (14.2, 42.1)

23.1 (14.5, 34.7)b1

18.7 (12.4, 27.1)

 Spec

 

90.8 (86.3, 93.9)

92.4 (87.8, 95.3)b2

93.6 (88.6, 96.5)

iFLCr ≥ 100 and iFLC ≥ 100 mg/L

30 (11.4%)

   

 Sens

 

25.7 (14.2, 42.1)

23.1 (14.5, 34.7)c1

18.7 (12.4, 27.1)

 Spec

 

90.8 (86.3, 93.9)

92.4 (87.8, 95.3)c2

93.6 (88.6, 96.5)

Sebia cut-points

N (%) of subjects who progressed

 

36 (12.7%)

66 (23.2%)

111 (39.1%)

iFLCr ≥ 100

26 (9.2%)

   

 Sens

 

19.4 (9.7, 35.0)

16.7 (9.6, 27.5)b1

13.5 (8.4, 21.1)

 Spec

 

92.3 (88.3, 95.0)

93.1 (88.9, 95.8)b2

93.6 (88.9, 96.4)

iFLCr ≥ 100 and iFLC ≥ 100 mg/L

25 (8.8%)

   

 Sens

 

16.7 (7.9, 31.9)

15.2 (8.5, 25.7)c1

12.6 (7.7, 20.0)

 Spec

 

92.3 (88.3, 95.0)

93.1 (88.9, 95.8)c2

93.6 (88.9, 96.4)

iFLCr cut-points for high-risk SMM, n = 238 patients

Freelite cut-pointsd

    

N (%) of subjects who progressed

 

23 (10.5%)

45 (20.6%)

80 (36.5%)

iFLCr > 20

72 (32.9%)

   

 Sens

 

52.2 (33.0, 70.8)

53.3 (39.0, 67.0)e1, f1

43.8 (33.5, 54.7)

 Spec

 

69.4 (62.6, 75.4)

72.4 (65.3, 78.5)e2,f2

73.4 (65.5, 80.0)

Sebia cut-points

N (%) of subjects who progressed

 

24 (10.1%)

46 (19.3%)

84 (35.3%)

iFLCr > 20

67 (28.2%)

   

 Sens

 

50.0 (31.4, 68.6)

45.7 (32.2, 59.9)f1

39.3 (29.5, 50.0)

 Spec

 

74.3 (68.1, 79.7)

76.0 (69.5, 81.5)f2

77.9 (70.7, 83.7)

  1. a21 did not have FreeLite involved FLC ratio (n = 263).
  2. b[1,2]McNemar’s p value = 0.35 and 0.62 for paired sensitivity (n = 65) and specificity (n = 198), respectively, between FreeLite iFLCr ≥ 100 and Sebia iFLCr ≥ 100.
  3. c[1,2]McNemar’s p value = 0.23 and 0.62 for paired sensitivity (n = 65) and specificity (n = 198), respectively, between FreeLite iFLCr ≥ 100 and FreeLite iFLC ≥ 100 mg/L and Sebia iFLCr ≥ 100 and Sebia iFLC ≥ 100 mg/L.
  4. dN = 219 because 19 did not have FreeLite involved FLC ratio.
  5. e[1,2]McNemar’s p value = 0.56 and 1.00 for paired sensitivity (n = 45) and specificity (n = 174), respectively, between FreeLite iFLCr > 20 and Sebia iFLCr > 16.
  6. f[1,2]McNemar’s p value = 0.29 and 0.16 for paired sensitivity (n = 45) and specificity (n = 174), respectively, between FreeLite iFLCr > 20 and Sebia iFLCr > 20.
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