RESUMO
BACKGROUND: Bronchiolitis obliterans syndrome (BOS) is one of the most severe complications and the leading cause of late mortality and morbidity after lung transplantation (LT) and allogeneic hematopoietic stem cell transplantation (allo-HSCT). No approved treatment for BOS is available. This review aimed to systematically identify and summarise the findings regarding the relationship between FEV1 decline and mortality in patients who developed BOS following LT or allo-HSCT. METHODS: A systematic literature search was performed in the Medline, Embase and Cochrane reviews databases. Of the 501 potential studies identified 25 met inclusion criteria and were analysed. RESULTS: Overall, 13 studies reported a relationship between FEV1 and mortality, and 12 studies reported both mortality and FEV1 results but did not investigate the relationship between them. There was heterogeneity in the analyses, which investigated the relationship between FEV1 decline and mortality across the studies in terms of levels of lung functioning, comparison to a control group, treatment, and statistical methodology; nevertheless, a clear and consistent increase in the risk of death associated with FEV1 decrease was seen in the analysed studies. CONCLUSIONS: The systematic literature review identified studies and findings that support a relationship between FEV1 and mortality, with a decrease in FEV1 being statistically associated with increased risk of death. Knowing that lower FEV1 levels are associated with higher mortality rates may help assess the condition of a patient with BOS and monitor future treatment effectiveness. However, more evidence is needed to further investigate this relationship and to verify its clinical usefulness.