Incidence, mortality of DAH high in patients with microscopic polyangiitis

Patients with microscopic polyangiitis (MPA) have increased incidence and mortality of diffuse alveolar haemorrhage (DAH), a recent study has shown.

In addition, age >65 years, serum creatinine (sCr) >500 μmol/L, the ratio of arterial oxygen partial pressure to fractional inspired oxygen (PaO₂/FiO₂) <300 mm Hg, and lung involvement area ≥50 percent are independently associated with MPA with DAH.

This retrospective study included 92 patients diagnosed with MPA with DAH at the First Affiliated Hospital of Chongqing Medical University between 1 March 2012 and 12 March 2018. The authors analysed the cumulative survival rate using the Kaplan-Meier method and obtained survival curves. They also used a Cox hazard model to determine the prognostic factors for survival by univariate and multivariate analysis.

Mean age at the onset of MPA with DAH was 66.32 years. Of the patients, 41 (44.57 percent) were critically ill and 79 (85.87 percent) had pulmonary and renal involvement.

All patients had cumulative survival rates of 63.7 percent at 1 year, 51.2 percent at 3 years, and 47.3 percent at 5 years, with a median survival time of 46 months.

Multivariate analysis revealed the following independent prognostic factors (p<0.05) for MPA with DAH: age >65 years (hazard ratio [HR], 4.30, 95 percent confidence interval [CI], 1.94–9.55), sCr >500 μmol/L (HR, 2.04, 95 percent CI, 1.05–3.97), PaO₂/FiO₂ <300 mm Hg (HR, 4.10, 95 percent CI, 1.97–8.53), and lung involvement area ≥50 percent (HR, 2.93, 95 percent CI, 1.40–6.13).