Detection of renal impairment as one specific comorbidity factor in multiple myeloma: multicenter study in 198 consecutive patients

Objectives: Comorbidity factors have been reported in cancer patients to predict progression free survival (PFS) and overall survival (OS). Renal impairment (RI) is postulated as one negative prognostic factor in multiple myeloma (MM). The study aim was to detect the best way to define RI and the impact of different RI stages on MM outcome. Methods: In this multicenter analysis, we determined RI [serum creatinine, estimated glomerular filtration rate (eGFR) by modification of diet in renal disease (MDRD) and Cockcroft-Gault] and other prognostic factors in 198 MM patients to ascertain their value on PFS and OS. Results: Median serum creatinine was 0.9 mg/dL in all patients, whereas the eGFR - being decreased with a median of 80 mL/min/1.73 m2- allowed to detect early stages of RI. Via univariate analysis, we observed increasing hazard ratios (HRs) for impaired OS with deteriorating eGFR: with eGFR(MDRD)< 90 and < 30, HRs were 1.3 and 2.9, respectively. Multivariate analysis determined RI with eGFR < 30 and < 50 as well as age > 59 yr as most important variables for OS. By incorporating eGFR < 30 as the most relevant factor determined via multivariate analysis and beta(2)-microglobulin (beta(2)-MG) in a novel MM-risk score, we identified patients with significantly differing OS: median survival with 0, 1 or 2 risk factors were 71, 48, and 24 months, respectively. Conclusions: These findings demonstrate that RI is frequent in MM, best detected via eGFR determination and an important prognostic factor. eGFR in combination with beta(2)-MG allows definitive risk stratification with largely differing survival in MM.