Table 2.
Baseline characteristics of the US RA cohort, by degree of ILD*
| RA–no ILD (ILA score 0) (n = 22) |
RA–indeterminate ILD (ILA score 1) (n = 15) |
RA–mild ILD (ILA score 2) (n = 34) |
RA–advanced ILD (ILA score 3) (n = 7) |
RA-ILD (ILA score 2 or 3) (n = 49)† |
|
|---|---|---|---|---|---|
| Demographic parameters | |||||
| Age, years | 50.32 ± 7.82 | 54.33 ± 12.24 | 63.38 ± 10.36‡ | 70.57 ± 14.29‡ | 65.27 ± 10.80‡ |
| Female, no. (%) | 16 (76) | 15 (100) | 12 (35) | 2 (29) | 18 (37) |
| White race, no. (%) | 15 (71) | 10 (67) | 25 (74) | 5 (71) | 37 (76) |
| Ever smoker, no. (%) | 8 (42) | 4 (29) | 18 (53) | 3 (43) | 27 (55) |
| Pack-years of smoking | 11.08 ± 13.66 | 4.81 ± 5.94 | 26.08 ± 27.51 | 40.00 ± 26.46 | 25.25 ± 24.96 |
| RA parameters | |||||
| RF, IU/ml | 143.75 ± 357.00 | 221.27 ± 220.04 | 390.07 ± 765.12 | 439.60 ± 519.81 | 409.65 ± 708.20 |
| Anti-CCP, units/ml | 154.59 ± 151.36 | 143.98 ± 146.99 | 122.20 ± 146.37 | 73.23 ± 97.50 | 142.58 ± 151.91 |
| 3-variable DAS28 | 3.29 ± 1.68 | 3.47 ± 1.36 | 3.73 ± 1.15 | 3.28 ± 0.77 | 3.74 ± 1.16 |
| No. of swollen joints | 3.45 ± 4.06 | 1.93 ± 2.62 | 2.88 ± 3.29 | 1.86 ± 1.86 | 2.89 ± 3.20 |
| Duration of RA, years | 8.38 ± 8.14 | 12.00 ± 9.33 | 12.94 ± 10.09 | 16.14 ± 13.74 | 12.80 ± 10.28 |
| Medication use (ever), no. (%) | |||||
| Prednisone | 15 (68) | 7 (47) | 20 (59) | 3 (43) | 28 (57) |
| Methotrexate | 14 (67) | 8 (53) | 21 (64) | 4 (57) | 30 (63) |
| Leflunomide | 2 (9) | 3 (20) | 11 (32) | 0 (0) | 14 (29) |
| TNFα inhibitor | 2 (9) | 4 (27) | 4 (12) | 3 (43) | 9 (18) |
| Dyspnea score (respiratory parameter)§ | 12.14 ± 12.61 | 20.07 ± 19.46 | 31.16 ± 29.64‡ | 58 ± 26.43‡ | 36.96 ± 29.77‡ |
| Spirometric parameters | |||||
| FEV1, percent of predicted | 100.17 ± 14.49 | 98.6 ± 11.60 | 79.82 ± 21.43‡ | 73.86 ± 23.42‡ | 77.73 ± 20.70‡ |
| FVC, percent of predicted | 101.44 ± 14.49 | 89.9 ± 19.53 | 78.03 ± 20.19‡ | 68.14 ± 22.18‡ | 74.83 ± 19.99‡ |
| DLCO, percent of predicted | 84.07 ± 18.71 | 75.88 ± 15.40 | 58.81 ± 15.86‡ | 54.00 ± 29.61‡ | 56.03 ± 17.58‡ |
Data in some categories were missing for some patients, as follows: sex (1 patient), race (1 patient), ever smoker (4 patients), pack-years of smoking (6 patients), RF (19 patients), DAS28 (28 patients), number of swollen joints (3 patients), duration of RA (3 patients), methotrexate use (2 patients), dyspnea score (5 patients), FEV1 (18 patients), FVC (18 patients), and DLCO (33 patients). Except where indicated otherwise, values are the mean ± SD. See Table 1 for definitions.
Includes 8 individuals with definite RA-ILD in whom a score of 2 versus 3 could not be distinguished.
P < 0.05 versus RA–no ILD.
Measured with the University of California, San Diego Shortness of Breath Questionnaire.