Occupational exposure to metal dust, wood dust and exhaust fume in Idiopathic Pulmonary Fibrosis (IPF)

<bold>Background:</bold> IPF is a progressive interstitial lung disease of unclear cause. Environmental and occupational exposures, particularly metals, wood dust and exhaust fume are associated with a diagnosis of IPF, although this relationship is not yet fully explained. <bold>Aim:</bold> To assess the prevalence and odds of occupational exposures to metals, wood dust and exhaust fume in IPF. <bold>Methods:</bold> Retrospective case-control study of 509 patients diagnosed with either IPF or COPD performed using data from 4 Birmingham (UK) hospital sites. Patients were categorised to IPF or non-IPF groups based on ILD MDT diagnosis. Demographic and clinical data were extracted from 393 patients who had occupational histories available from electronic medical records. Jobs were standardised and coded according to ISCO-88 occupational classification system; the OAs-JEM (job exposure matrix) was applied to subsequently determine exposures. Occupational exposures were compared between IPF and non-IPF groups. <bold>Results:</bold> 261 IPF (mean [SD] age = 72[8.9] years; 70% male) and 132 non-IPF (age = 71[9.7] years; 71% male) patients were included in this study. Craft and related trades were the commonest occupational group represented in both IPF and non-IPF cohorts (26% in both). 13%, 2% and 8% of IPF patients were exposed to metal (dust and fume), wood dust and exhaust fume respectively. No association between metal (odds ratio [OR] 1.33, 95% CI 0.67–2.61) or exhaust fume exposure (OR 0.92, 95% CI 0.44–1.92) and IPF was seen. <bold>Discussion:</bold> Lower exposure to wood dust was seen than reported in the literature. Analysis was undertaken on longest held job only rather than lifetime exposure and may therefore under-estimate exposures. Equipoise persists regarding the relationship of metal and exhaust fume occupational exposure and IPF.