Clinical Characteristics and Risk Factors for Pleural Effusion in Patients with Multiple Myeloma.

Purpose Pleural effusion (PE) is prevalent in "real-life" populations of multiple myeloma (MM), a common hematologic malignancy. Development of PE likely has prognostic implications. The aim of this study was to investigate the characteristics and identify risk factors for occurrence of PE in MM. Patients and methods We reviewed electronic medical records of 907 patients diagnosed with MM. Results Incidence of PE in MM patients was 42.7%. Small and bilateral PE in most cases. PE developed in all MM subtypes, the median time from diagnosis of multiple myeloma to pleural effusion was 6.8 months (range 0.8-33.6 months). Patients with PE showed worse survival than those without PE (unadjusted hazard ratio with 95% confidence interval: 2.249 [1.774-2.852]). No difference in survival was found between patients with small PE and those with moderate to large PE (unadjusted HR, 1.402; 95% CI, 1.037-1.896). Plasma cell proportion (OR, 1.373; 95% CI, 1.153-1.634; P = 0.009) and amyloidosis (OR, 1.791; 95% CI, 1.408-2.279; P = 0.024) were risk factors for the occurrence of PE at the initial diagnosis of MM. Plasma cell proportion (OR, 1.853; 95% CI, 1.451-2.368; P = 0.038), pneumonia (OR, 1.309; 95% CI, 1.143-1.498; P = 0.008) and heart failure (OR, 1.815; 95% CI, 1.387-2.374; P = 0.031) were risk factors for the occurrence of PE at relapse of MM. Conclusion The incidence of PE in MM patients is notable and PE can occur in all MM subtypes. PE indicates a poor prognosis, even small amounts of effusion. PE is a problem worthy of attention, especially in patients with high plasma cell proportion, amyloidosis or complicated with pneumonia and heart failure.