Baseline characteristics, management and outcomes of the study cohort
| Age years | 61.5 (54.4–71.1) |
| Sex | |
| Female | 66 (42) |
| Male | 90 (58) |
| Body height cm | 160.9±9.3 |
| Body weight kg | 60.3 (53.7–66.6) |
| Charlson comorbidity index | 3 (2–5) |
| Cigarette smoking status | |
| Never-smoker | 105 (67) |
| Current smoker | 29 (19) |
| Former smoker | 22 (14) |
| Time between CT and histologic diagnosis of OP, days | 13 (7–30) |
| Method of biopsy | |
| Surgical | 91 (58) |
| CT-guided percutaneous | 49 (31) |
| Transbronchial forceps | 15 (10) |
| Sonography-guided percutaneous | 1 (1) |
| Season of diagnosis | |
| Spring (March–May) | 40 (26) |
| Summer (June–August) | 50 (32) |
| Autumn (September–November) | 37 (24) |
| Winter (December–February) | 29 (18) |
| Aetiology | |
| Cryptogenic | 130 (83) |
| Secondary | 26 (17) |
| CTD-related | 14 (9) |
| Rheumatoid arthritis | 6 (4) |
| Dermatomyositis/polymyositis | 3 (2) |
| Primary Sjögren's syndrome | 3 (2) |
| Anti-synthetase syndrome | 1 (1) |
| Systemic lupus erythematosus | 1 (1) |
| Drug-related | 10 (6) |
| Amiodarone | 5 (3) |
| Pembrolizumab | 2 (2) |
| Agent(s) in cancer chemotherapeutic regimens | 2 (2) |
| Crizotinib | 1 (1) |
| Post-transplantation | 2 (2) |
| Duration of follow-up, weeks | 120.6 (31.1–269.4) |
| Treatments | |
| Observation only | 45 (29) |
| Surgical resection | 48 (31) |
| Corticosteroid alone | 55 (35) |
| Combined corticosteroid and another immunosuppressant | 7 (4) |
| Non-steroid immunosuppressant | 1 (1) |
| Needed supplementary oxygen during the course | 41 (26) |
| Needed mechanical ventilatory support during the course | 17 (11) |
| Outcomes | |
| Improved without recurrence | 129 (82) |
| Persistent disease | 11 (7) |
| Improved but then recurred | 5 (3) |
| Death | 11 (8) |
Discrete variables are presented as counts (% of the total 156 patients). Continuous variables are presented as mean±sd if normally distributed, and medians (interquartile ranges) if not normally distributed. CT: computed tomography; OP: organising pneumonia; CTD: connective tissue disease.