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Table 1 Demographic characteristics of matched and unmatched cohorts

From: Thymectomy for non-thymomatous myasthenia gravis: a propensity score matched study

Characteristics

Unmatched (n = 395)

Matched (n = 98)

 

Thymectomy (n = 183)

Controls (n = 212)

Absolute standardized difference

Thymectomy (n = 49)

Controls (n = 49)

Absolute standardized difference

Age (mean ± SD)

34.8 ± 14.1

63.7 ± 12.7*

2.33

49.8 ± 14.3

50.1 ± 13.2

0.02

Females [n (%)]

124(68)

89(42)*

2.03

25(51)

27(50)

0.08

Time to Dx (mean ± SD)

14.8 ± 26.1

16.9 ± 31.8

0.55

17.8 ± 25.6

18.3 ± 27.3

0.02

MGFA class at diagnosis n [(%)]

 MGFA I

16(9)

31(15)*

0.21

5(10)

4(8)

0.07

 MGFA II

57(31)

81(38)

0.15

21(43)

23(47)

0.08

 MGFA III

70(38)

73(34)

0.08

17(35)

15(31)

0.08

 MGFA IV/V

40(22)

27(13)*

0.22

6(12)

7(14)

0.05

Medications [n(%)]

Prednisone

130(71)

166(78)

0.16

35(71)

33(67)

0.09

Azathioprine

109(60)

118(56)

0.08

30(61)

31(63)

0.04

Mycophenolate

32(18)

41(19)

0.05

6(12)

7(14)

0.05

Other immunosupressants

28(15)

21(10)

0.15

4(8)

5(10)

0.07

Follow-up (mean ± SD)

118.9 ± 115.9

67.4 ± 52.8*

0.44

95.9 ± 103.1

76.4 ± 54.6

0.16

  1. Continuous data are expressed as median and range.
  2. Nominal data are expressed as number and proportion of patients.
  3. MGFA: Myasthenia Gravis Foundation of America. The proportion of patients in each MGFA class at diagnosis, before treatment, is presented for both groups.
  4. Time to Diagnosis (Dx) and Follow-up are in months.
  5. Other immunosupressants include: methotrexate, rituximab, cyclosporine and cyclophosphamide.
  6. Absolute Standardized Difference > 0.1, indicating poor balance of the variable between groups.
  7. *p < 0.05. p-values are less sensitive than the Absolute Standardized Difference to detect imbalance.
  8. The matched dataset has excellent balance of all the variables, except mild residual imbalance of follow-up times. This was accounted with time-to-event analyses.