Plasma exchange when myeloma presents as acute renal failure: A randomized, controlled trial

Background: Two small, randomized trials provide conflicting evidence about the benefits of plasma exchange for patients with acute renal failure at the onset of multiple myeloma. Objective: To assess the effect of 5 to 7 plasma exchanges on a composite outcome in patients with acute renal failure at the onset of multiple myeloma. Design: Randomized, open, controlled trial, stratified by chemotherapy and dialysis dependence, conducted from 1998 to 2004. Setting: Hospital plasma exchange units in 14 Canadian medical centers. Participants: 104 patients between 18 and 81 years of age with acute renal failure at the onset of myeloma. Intervention: Study participants were randomly assigned to conventional therapy plus 5 to 7 plasma exchanges of 50 mL per kg of body weight of 5% human serum albumin for 10 days or conventional therapy alone. Ninety-seven participants completed the 6-month follow-up. Measurements: The primary outcome was a composite measure of death, dialysis dependence, or glomerular filtration rate less than 0.29 mL · s^-2 · m^-2 (<30 mL/min per 1.73 m²). Results: At enrollment, the plasma exchange and control groups were similar for dialysis dependence, chemotherapy, sex, age, hypercalcemia, serum albumin level, 24-hour urine protein level, serum creatinine level, and Durie-Salmon staging. The primary composite end point occurred in 33 of 57 (57.9%) patients in the plasma exchange group and in 27 of 39 (69.2%) patients in the control group (difference between groups, 11.3% [95% CI, -8.3% to 29.1%]; P = 0.36). One third of patients in each group died. Limitations: The study was small, used a composite outcome, and did not use renal biopsy as an inclusion criterion. Recruiting physicians were blinded to treatment allocation but not to treatment thereafter. Conclusions: In patients with acute renal failure at the onset of multiple myeloma, there is no conclusive evidence that 5 to 7 plasma exchanges substantially reduce a composite outcome of death, dialysis dependence, or glomerular filtration rate less than 0.29 mL · s^-2 · m^-2 (<30 mL/min per 1.73 m²) at 6 months.