Does previous asbestos exposure increase the risk of a post coronary artery bypass graft (CABG) pleural effusion - a routine data study?

backgroundDevelopment of pleural effusion (PE) following CABG is common. Post-CABG PE are divided into early- (within 30 days of surgery) and delayed-onset (30 days-1 year) which are likely due to distinct pathological processes. Some experts suggest asbestos exposure may confer an independent risk for late-onset post-CABG PE, however no large studies have explored this potential association. RESEARCH QUESTION: To explore possible association between asbestos exposure and post-CABG PE using routine data.

methodsAll patients who underwent CABG 01/04/2013-31/03/2018 were identified from the Hospital Episode Statistics (HES) Database. This England-wide population was evaluated for evidence of asbestos exposure, pleural plaques or asbestosis and a diagnosis of PE or PE-related procedure from 30 days to 1 year post-CABG. Patients with evidence of PE three months prior to CABG were excluded, as were patients with a new mesothelioma diagnosis.

results68,150 patients were identified, of whom 1,003 (1%) were asbestos exposed and 2,377 (3%) developed late-onset PE. After adjusting for demographic data, Index of Multiple Deprivation and Charlson Co-morbidity Index, asbestos exposed patients had increased odds of PE diagnosis or related procedure such as thoracentesis or drainage (OR 1.35, 95% CI 1.03-1.76, p = 0.04). In those with evidence of PE requiring procedure alone, the adjusted OR was 1.66 (95% CI 1.14-2.40, p = 0.01). Additional subgroup analysis of the 518 patients coded for pleural plaques and asbestosis alone revealed an adjusted OR of post-CABG PE requiring a procedure of 2.16 (95% CI 1.38-3.37, p = 0.002).

interpretationThis large-scale study demonstrates prior asbestos exposure is associated with modestly increased risk of post-CABG PE development. The risk association appears higher in patients with assigned clinical codes indicative of radiological evidence of asbestos exposure (pleural plaques or asbestosis). This association may fit with a possible inflammatory co-pathogenesis, with asbestos exposure 'priming' the pleura resulting in greater propensity for PE evolution following the physiological insult of CABG surgery. Further work, including prospective studies and clinicopathological correlation are suggested to explore this further.