Decreased body mass index is associated with poor prognosis in patients with multiple myeloma

Obesity increases morbidity in and mortality of patients with various types of cancer. However, the proportion of obese individuals in Asia is smaller than that in Western populations and only a few studies have explored the effect of obesity at the time of diagnosis on the survival of Asian patients with multiple myeloma (MM). Therefore, we investigated the relationship between body mass index (BMI) at diagnosis, and clinical manifestations, in MM patients. We also measured overall survival (OS) in terms of BMI groupings. Patients were subdivided into three groups based on hazard ratios (HRs) associated with BMIs of <20, 20–24.9, and ≥25 kg/m². The median survival times were 25.5 months in patients with a BMI of <20 kg/m², 56.8 months for those with a BMI of 20–24.9 kg/m², and 76 months in patients with a BMI of ≥25 kg/m². Patients with a BMI of <20 kg/m² exhibited poorer performance status and a lower hemoglobin level at diagnosis than did others, and renal failure (serum creatinine ≥2 mg/dl) was much more often observed in such patients than in those of other groups. Both univariate and multivariate analyses showed that BMI <20 kg/m² (HR 1.831, 95 % confidence interval [CI] 1.005–3.337; P = 0.048) and performance of autologous stem cell transplantation (HR 0.257, 95 % CI 0.139–0.475, P < 0.001) were significantly (negatively) associated with OS. In conclusion, a low BMI (<20 kg/m²) at the time of diagnosis was associated with poor survival of MM patients.