Impact of body mass index at different transplantation stages on postoperative outcomes in patients with hematological malignancies: a meta-analysis

Although the association between body mass index (BMI) and overall survival (OS) has been reported in leukemia patients of different ages, whether BMI levels at different stages of hematopoietic stem cell transplantation (HSCT) have different effects on postoperative survival remains controversial. We searched four electronic databases from inception through July 2017 without any language restrictions and included studies on different types of hematological malignancies reporting both BMI time points and HSCT. Of the 1420 articles identified, 26 articles were eligible for inclusion in this meta-analysis. Three weight groups (obese, overweight and underweight) were individually compared with the normal group. Summary risk estimates for OS and event-free survival (EFS) were calculated with random- or fixed-effects models. For BMI at the pre-HSCT stage, a statistically significant positive association of increased risk of OS (RR: 1.17; 95% CI: 1.08–1.27) and EFS (RR: 1.29; 95% CI: 1–1.67) was identified in underweight individuals compared with those with normal weights. For BMI in the HSCT stage, a lower BMI was significantly associated with poorer OS (RR: 1.34; 95% CI: 1.01–1.78) and EFS (RR: 1.53; 95% CI: 1.09–2.06) compared with a normal BMI. Our results indicated that lower BMI at the pre-HSCT stage or during HSCT is associated with poorer survival.