Multiple myeloma and high cut-off haemodialysis: On the right track for better outcomes?

Background: Acute kidney injury secondary to cast nephropathy is a common complication of multiple myeloma. Extracorporeal light chain elimination by high cut-off haemodialysis has been described as an adjuvant to effective chemotherapy to limit free light chain toxicity. The purpose of this study was to evaluate the impact of high cut-off haemodialysis and bortezomib-based chemotherapy on renal function recovery and overall survival in a cohort of patients with multiple myeloma and dialysis-dependent acute kidney injury. Methods: We did a historical cohort study of patients with multiple myeloma and dialysis-dependent acute kidney injury presenting to our Centre between the 1st January 1999 and 31st March 2013. Results: Forty-six patients were included, with a median age of 68 (56-73 Y) years old. Twenty-four per cent recovered renal function. Patients submitted to high cut-off haemodialysis had a significantly higher probability of renal function recovery (OR = 11.5; 95% IC: 1.0 to 126.5). Seventy-two per cent of the patients died. The median survival rate was 20 months and overall 1-year survival rate was 58.3%. Male sex was associated with worse overall survival (HR = 4.9; 95% CI: 2.0-12.3). Renal function recovery decreased the risk of death (HR = 0.24; 95% CI: 0.07-0.80) as compared with those who remained on dialysis. The use of HCOH had no influence on the risk of death. Conclusions: Adding high cut-off haemodialysis to the novel anti-myeloma agents was independently associated to better renal outcomes in patients with multiple myeloma and dialysis-dependent acute kidney injury. However, our confidence in these results is hampered by the observational nature of the study, and by the small sample size and imprecise estimates of effect. Randomized controlled trials addressing this issue are urgently needed.