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