Table 4.
Case-Referent Studies of Occupational Risk Factors for Idiopathic Pulmonary Fibrosis
| First Author, Year, Location (Reference) | Cases (N) | IPF Case Definition Criteria | OR (95% CI) |
PAF (%) |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| VGDF | Metal | Wood | Ag | Silica | VGDF | Metal | Wood | Ag | Silica | |||
| Scott, 1990, UK (77) | 40 | Clinical, CXR, PFT | 1.3 (0.8–2.0) | 11.0 (2.3–52.4) | 2.9 (0.9–9.9) | 10.9 (1.2–96) | 1.6 (0.5–4.8) | 17 | 12 | 10 | 12 | 5 |
| Hubbard, 1996, UK (79) | 218 | Clinical, CXR, CT, PFT | NA | 1.7 (1.1–2.7) | 1.7 (1.0–2.9) | NA | NA | NA | 10 | 6 | NA | NA |
| Mullen, 1998, USA (80) | 15 | Clinical, lung biopsy, CT | 2.4 (0.7–8.4) | NA | 3.3 (0.4–25.8) | NA | 11.0 (1.1–115) | 20 | NA | 7 | NA | 20 |
| Baumgartner, 2000, USA (81) | 248 | Clinical, biopsy, CT | NA | 2.0 (1.0–4.0) | 1.6 (0.8–3.3) | 1.6 (1.0–2.5) | 3.9 (1.2–12.7) | NA | 5 | 3 | 7 | 2 |
| Hubbard, 2000, UK (82) | 22 | Death certificate | NA | 1.1 (0.4–2.7) | NA | NA | NA | NA | 5 | NA | NA | NA |
| Miyake, 2005, Japan (83) | 102 | Lung biopsy, BAL, CT | 5.6 (2.1–17.9) | 9.6 (1.7–181.1) | 6 (0.3–112.4) | NA | 1.8 (0.5–7.0) | 26 | 11 | 4 | NA | 5 |
| Gustafson, 2007, Sweden (84) | 140 | Pulmonary fibrosis requiring tissue | 1.1 (0.7–1.7) | 0.9 (0.5–1.6) | 1.2 (0.7–2.2) | NA | 1.4 (0.7–2.7) | 6 | NA | 3 | NA | 3 |
| García-Sancho, 2011, Mexico (87) | 100 | Clinical, CT, lung biopsy | 2.8 (1.5–5.5) | NA | NA | NA | NA | 50 | NA | NA | NA | NA |
| Awadalla, 2012, Egypt (Men) (88) | 95 | Clinical, CT, PFT | NA | 1.6 (0.7–3.6) | 2.7 (1.1–6.8) | 1.0 (0.4–2.3) | 1.1 (0.5–2.7) | NA | 6 | 9 | NA | 1 |
| Awadalla, 2012, Egypt (Women) (88) | 106 | Clinical, CT, PFT | NA | NA | 4.3 (0.8–22.1) | 3.3 (1.2–10.1) | NA | NA | NA | 6 | 14 | NA |
| Paolocci, 2013, Italy (92) | 65 | Clinical, CT | NA | 2.8 (1.1–7.2) | 1.1 (0.4–3.3) (soft wood) | NA | 2.0 (0.9–4.4) | NA | 9 | 0 | NA | 11 |
| 0.9 (0.3–2.8) (hard wood) | 0 | |||||||||||
| Koo, 2017, Korea (91) | 78 | Clinical, CT | 2.7 (0.7–10.9) | 5.0 (1.4–18.2) | 2.5 (0.5–12.4) | NA | 1.2 (0.4–3.8) | 35 | 22 | 5 | NA | 5 |
Definition of abbreviations: Ag = agricultural dusts; CI = confidence interval; CT = computed tomography; CXR = chest radiograph; IPF = idiopathic pulmonary fibrosis; NA = not applicable; OR = odds ratio; PAF = population attributable fraction; PFT = pulmonary function test; UK = United Kingdom; USA = United States; VGDF = vapors, gas, dust, or fumes, which represent all the exposure categories shown combined and, in selected studies, additional exposures as well.
All studies had case–control designs, with most by interview-based self-reported exposure assessment (Hubbard exposure by job category). Awadalla and colleagues stratified their study sample by male (n = 95) and female (n = 106). The study by Paolocci and colleagues, which estimated risk with two separate wood variables, later appeared as a full publication (89).