Risk factors and outcomes of diffuse alveolar haemorrhage after allogeneic haematopoietic stem cell transplantation

Diffuse alveolar haemorrhage (DAH) is a life-threatening pulmonary complication occurring after allogeneic haematopoietic stem cell transplantation (allo-HSCT) without an explicit aetiology or a standard treatment. This study aimed to explore the occurrence and prognosis of DAH after allo-HSCT, in addition to comparing discrepancies in the incidence, clinical characteristics and outcomes of DAH between patients undergoing haploidentical HSCT (HID-HSCT) and matched related donor HSCT (MRD-HSCT). We retrospectively evaluated 92 consecutive patients among 3987 patients with a confirmed diagnosis of DAH following allo-HSCT (HID: 71 patients, MRD: 21 patients). The incidence of DAH after allo-HSCT was 2.3%, 2.4% after HID-HSCT and 2.0% after MRD-HSCT (P = 0.501). The prognosis of patients with DAH after transplantation is extremely poor. The duration of DAH was 7.5 days (range, 1–48 days). The probabilities of overall survival (OS) were significantly different between patients with and without DAH within 2 years after transplantation (P < 0.001). According to the Cox regression analysis, a significant independent risk factor for the occurrence of DAH was delayed platelet engraftment (P < 0.001), and a high D-dimer level (>500 ng/ml) was a significant risk factor for the poor prognosis of DAH. HID-HSCT is similar to MRD-HSCT in terms of the outcomes of DAH.