Clinical characteristics
| Characteristics | Total N=51 (100) | Non-AE group† N=40 (78) | AE group‡ N=11 (22) | p Value§ |
|---|---|---|---|---|
| Median age, years (range) | ||||
| At RA diagnosis | 61 (28–82) | 60 (28–81) | 65 (42–82) | 0.15 |
| At ILD diagnosis | 62 (31–83) | 62 (31–83) | 69 (58–83) | 0.15 |
| At AE onset | 72 (60–86) | |||
| Sex male, n (%) | 29 (57) | 23 (58) | 6 (55) | 0.86 |
| Observation period, years (range) | 8.5 (1–17) | 9 (1–17) | 6.4 (2–14) | 0.45 |
| AE-free period, years (range) | 7 (1–17) | 9 (1–17) | 6 (2–14) | 0.19 |
| Smoking habit, n (%) | ||||
| Never | 20 (39) | 18 (45) | 2 (18) | 0.15 |
| Former | 24 (47) | 16 (40) | 8 (73) | |
| Current | 7 (14) | 6 (15) | 1 (9) | |
| RF, IU/mL (range)¶ | 197 (6–2666) | 189 (6–2666) | 205 (39–2530) | 0.47 |
| DAS28-CRP, score (range)¶ | 1.95 (1.02–5.13) | 2.53 (1.02–5.13) | 1.82 (1.47–2.3) | 0.62 |
| PaO2, torr (range) | 82.4 (67–109) | 81 (67–102) | 85.8 (74–109) | 0.19 |
| %FVC, % (range) | 91.1 (50.6–130) | 87.5 (51–130) | 95 (60–125) | 0.38 |
| HRCT pattern, n (%) | ||||
| UIP pattern | 14 (27) | 8 (20) | 6 (55) | 0.02* |
| Non-UIP pattern | 37 (73) | 32 (80) | 5 (45) | |
| Death during observation period, n (%) | ||||
| Caused by respiratory failure | 9 (18) | 2 (5) | 7 (64) | 0.02* |
| Caused by other diseases | 3 (6) | 3 (8) | 0 (0) | |
Data are presented as n (%), median (range).
When HRCT pattern was identified as a UIP pattern, the positive predictive value and negative predictive value for AE occurrence was 42.9% and 86.5%, respectively.
In the AE group, seven patients died of respiratory failure caused by AE. In the non-AE group, two died of respiratory failure caused by bacterial pneumonia or pneumocystis pneumonia, one of gastric bleeding and two of unknown causes.
*p < 0.05.
†Non-AE group, patients who did not develop AE during observation period.
‡AE group, patients who developed AE during observation period.
§Non-AE group versus AE group.
¶At the first AE occurrence (AE group) or the last visit (non-AE group).
AE, acute exacerbation; DAS28-CRP, disease activity score 28 C reactive protein; %FVC, predicted forced vital capacity; HRCT, high resolution CT; ILD, interstitial lung disease; PaO2, arterial oxygen pressure; RA, rheumatoid arthritis; RF, rheumatoid factor; UIP pattern, usual interstitial pneumonia pattern.