Clinical outcomes and survival following lung transplantation for work-related lung disease: a single-center retrospective cohort study

Our study for the first time analyzed the clinical outcomes and survival following LTx for WRLD in China. Artificial stone-associated silicosis accounted for most of our WRLD patients. Pneumothorax was the primary indication for LTx in the WRLD patients. WRLD and IPF patients had comparable post-transplant survival rate and complications.

Our study showed that the WRLD patients constituted 8.0% of the total patients who received LTx at our hospital, which is consistent with a previous number of 9.2% in a national report [8]. This result is unsurprising because our center ranks the second among the three major lung transplant centers in China. WRLD is prevalent worldwide and has maintained a high incidence in recent years [9]. However, the proportion of WRLD patients in LTx in our study is much higher than that reported in other parts of the world, which is between 0.5–1% [10, 11]. The underlying reason may be the high prevalence of WRLD in China, which is related to multiple factors such as poor work conditions, scarce of medical facility, rural area of residence, and low economic status of the workers [12, 13].

WRLD is often associated with extensive pleural adhesions, which may lead to severe bleeding during pleural dissection and lung transplantation. Therefore, significantly more patients in the WRLD group received single-lung transplantation to reduce the risk of major intraoperative bleeding. The WRLD patients had worse lung function compared to the IPF patients, and lung function tests showed that the former had both obstructive and restrictive pulmonary dysfunction. In addition, significantly more WRLD patients had spontaneous pneumothorax compared to the IPF patients, especially in those with silicosis. Also, multiple lung blebs were shown in thoracic CT images of these patients. Taken together, our study suggested that patients with WRLD suffered from impaired ventilation and restricted spirometry [14].

The association between silica exposure and emphysema has been noted [15]. Silicosis is an independent risk factor for pneumothorax [16]. Massive lung fibrosis can cause increased elastic recoil and collapse of the adjacent regions, leading to uneven expansion of the lung and pressure gradient, and finally rupture of the blebs [17]. More than half of our WRLD patients had spontaneous pneumothorax and even recurrent and non-curable pneumothorax. Pneumothorax was firstly managed with negative pressure drainage. Patients with poor response to this treatment were switched to pleurodesis induced by talcum powder. LTx was chosen as the final treatment if all these conservative treatments fail, and the patient develops respiratory failure. Thus, LTx might be the last resort for these patients. Our study suggested that spontaneous pneumothorax is a reasonable indication for LTx in patients with end-stage WRLD.

During the transplantation surgery and the immediate post-operative periods, severe chest wall bleeding or hemothorax were significantly more common in the WRLD group than the IPF group. No significant differences were noticed in other immediate post-operative outcomes including mechanical ventilator support, primary graft dysfunction, and ICU stay duration between the two groups. Long-term survival after transplantation was also similar between the WRLD and the IPF patients. Previous studies have also reported good clinical outcomes and survivability for WRLD patients after LTx [18,19,20]. In our study, the post-transplant lung function in the WRLD group was still slightly lower than the IPF group. This could be associated with the better baseline lung function and more double LTx in the IPF patients.

However, both groups of patients had significant improvement in 6MWD after transplantation, although no significant difference was noticed between the two groups. Therefore, LTx is a valid and effective treatment for end-stage WRLD.

Our study has some limitations. Firstly, although our center covers the south China, the findings should be cautiously interpreted due to the single-center study design and the small sample size. Secondly, the high 5-year mortality led to significantly less survival patients, which may bias our results. Thirdly, the younger age and the higher proportion of sing-lung transplantation in the WRLD group may have potentially improved survival and lung function in these patients. Fourthly, quite many of our patients did not have lung function tests due to poor physical status and post-transplant complications. The high proportion of missing data may reduce the statistical power of lung function.

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