Table 1. Characteristics of 167 Patients with Interstitial Lung Disease and Rheumatoid Arthritis by Type of Interstitial Lung Disease.
| Characteristic | NSIP (n=70) | UIP (n=89) | OP (n=8) | Total* (n=167) |
|---|---|---|---|---|
| Age at ILD diagnosis, years | 67.3 (±9.9) | 68.2 (±9.7) | 56.2 (±8.9) | 67.3 (±10.0) |
| Age at RA diagnosis, years | 59.5 (±14.4) | 59.5 (±12.3) | 50.1 (±10.7) | 59.0 (±13.2) |
| Ethnicity, Caucasian (n, %) | 68 (97%) | 84 (97%) | 7 (88%) | 159 (97%) |
| Sex, female (n, %) | 37 (53%) | 40 (55%) | 4 (50%) | 81 (49%) |
| Smoking status | ||||
| Never (n, %) | 30 (43%) | 31 (35%) | 1 (13%) | 62 (37%) |
| Former (n, %) | 38 (54%) | 57 (64%) | 6 (75%) | 101 (60%) |
| Current (n, %) | 2 (3%) | 1 (1%) | 1 (13%) | 4 (2%) |
| Length of follow-up from ILD diagnosis, years, median (range) | 4.3 (0.1 – 13.4) | 3.7 (0.1 – 14.8) | 3.7 (0.1 – 8.8) | 3.3 (0.1 – 14.8) |
| RA disease duration at ILD diagnosis, years, median (range) | 3.6 (-10.9 – 48.1) | 5.4 (-9.8 – 43.0) | 2.4 (-1.7 – 19.1) | 4.2 (-10.9 – 48.1) |
| RF positive, n positive/ n tested (%) | 56 / 68 (82%) | 74 / 87 (85%) | 4 / 8 (100%) | 134 / 163 (82%) |
| ACPA positive, n positive/ n tested (%) | 51 / 64 (80%) | 47 / 59 (80%) | 3 / 6 (50%) | 101 / 129 (78%) |
| Erosive disease (n, %) | 16 (23%) | 22 (25%) | 3 (38%) | 41 (25%) |
| Extra-articular manifestations other than ILD (n, %) | 31 (44%) | 38 (43%) | 4 (50%) | 73 (44%) |
| Rheumatoid nodules | 16 (23%) | 25 (28%) | 1 (13%) | 42 (25%) |
| Severe extra-articular manifestations other than ILD (n, %) | 4 (6%) | 6 (7%) | 2 (25%) | 12 (7%) |
| Emphysema on chest HRCT | 8 (11%) | 13 (15%) | 1 (13%) | 22 (13%) |
| Required supplemental oxygen at ILD diagnosis (n, %) | 6 (9%) | 17 (19%) | 0 (0%) | 23 (14%) |
| Oxygen requirement at last visit (liters/minute) | 3.0 (±2.1) | 2.7 (±1.2) | 3.0 (±1.4) | 2.8 (±1.5) |
*
Values in table are mean (±standard deviation) or n (%) unless otherwise specified
Abbreviations: Anti-citrullinated protein antibody (ACPA), number (n), high-resolution computed tomography (HRCT), interstitial lung disease (ILD), rheumatoid arthritis (RA), rheumatoid factor (RF), nonspecific interstitial pneumonia (NSIP), organizing pneumonia (OP), usual interstitial pneumonia (UIP)