Clinical characteristics of autoimmune rheumatic disease-related organizing pneumonia

To study the clinical characteristics of autoimmune rheumatic disease-related organizing pneumonia (AIRD-OP), the clinical presentation, radiological findings, treatment, and outcome of AIRD-OP patients were analyzed, in comparison with patients with cryptogenic organizing pneumonia (COP). A total of 131 OP patients were identified, including 57 cases of AIRD-OP, 35 cases of COP, and 39 cases of other disease-related OPs. Among AIRD-OP patients, 36 (63%) presented the symptoms of OP at onset. The primary disease of AIRDs included Sjogren's syndrome (38%), polymyositis/dermatomyositis (23%), rheumatoid arthritis (23%), and undifferentiated AIRD. Compared with COP patients, the prevalence of patients having cough and malaise at baseline was significantly lower (54.4 vs 82.9%, P < 0.05; 49.1 vs 70.6%, P < 0.05), and the signs of moist rales and crackles were more common in AIRD-OP patients (54.4 vs 32.4%, P < 0.05; 49.1 vs 26.5%, P < 0.05). Lung function (TLC%, FVC%) was more significantly reduced in AIRD-OP patients (72 vs 97%, P < 0.05;75 vs 96%, P < 0.05). The dosage of corticosteroids prescribed was significantly higher in AIRD-OP patients (44 vs 37 mg/day, P < 0.05). The complete recovery rate was slightly lower in AIRD-OP patients (22.2 vs 29%, P > 0.05) with a tendency towards higher recurrence rate in AIRD-OP patients (32.7 vs 14.3%, P < 0.05). AIRD-OP may be the most common cause of OP. OP can be the initial presentation of AIRD. Compared with COP patients, AIRD-OP patients are characterized with occult onset but more severe lung involvement and higher recurrence rate.