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Table 3 Sensitivity Analysis of Incidence Rates per 100,000 person-years (2004–2008)

From: Incidence and prevalence of idiopathic inflammatory myopathies among commercially insured, Medicare supplemental insured, and Medicaid enrolled populations: an administrative claims analysis

 

Commercial and Medicare supplemental database

Medicaid database

 

N

Crude rate

Age & Gender adjusted rate

95% CI for adjusted rate

N

Crude rate

Age & Gender adjusted rate

95% CI for adjusted rate

Base case analysis (IIMs)

2,477

4.88

4.27

4.09-4.44

513

5.20

5.23

4.74-5.72

Dermatomyositis

902

1.78

1.52

1.42-1.63

170

1.72

1.70

1.42-1.97

Polymyositis

1,438

2.83

2.46

2.33-2.59

346

3.51

3.53

3.13-3.94

Interstitial myositis

401

0.79

0.73

0.66-0.81

75

0.76

0.78

0.58-0.97

Presence of muscle biopsy one year prior to or one year following index date

IIMs

738

1.45

1.25

1.16-1.35

102

1.03

1.05

0.83-1.27

Dermatomyositis

248

0.49

0.43

0.38-0.49

34

0.34

0.34

0.22-0.46

Polymyositis

574

1.13

0.96

0.88-1.04

88

0.89

0.91

0.70-1.11

Interstitial myositis

21

0.04

0.04

0.02-0.06

2

0.02

0.02

0.01-0.04

Presence of specialist visit on index date or in the year following

IIMs

535

1.05

0.91

0.82-0.99

64

0.65

0.63

0.46-0.79

Dermatomyositis

207

0.41

0.35

0.30-0.40

21

0.21

0.24

0.13-0.35

Polymyositis

374

0.74

0.63

0.56-0.70

49

0.50

0.46

0.32-0.59

Interstitial myositis

27

0.05

0.05

0.03-0.07

8

0.08

0.06

0.02-0.10

Presence of immunosuppressants and/or systemic corticosteroids one year following index date

IIMs

1,761

3.47

3.01

2.86-3.16

304

3.08

3.07

2.70-3.44

Dermatomyositis

725

1.43

1.24

1.14-1.33

103

1.04

1.02

0.80-1.23

Polymyositis

1,146

2.26

1.96

1.84-2.08

225

2.28

2.29

1.97-2.61

Interstitial myositis

133

0.26

0.23

0.19-0.27

32

0.32

0.31

0.20-0.43

Presence of any of the above (combined sensitivity criteria)

IIMs

1,917

3.78

3.29

3.13-3.44

347

3.52

3.50

3.10-3.89

Dermatomyositis

758

1.49

1.29

1.20-1.39

115

1.17

1.13

0.91-1.36

Polymyositis

1,250

2.46

2.14

2.01-2.26

257

2.61

2.62

2.28-2.97

Interstitial myositis

160

0.32

0.28

0.24-0.33

38

0.38

0.36

0.24-0.48

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