The Effect of Obesity On Outcome of Unrelated Cord Blood Transplant in Children with Malignant Diseases.

Abstract 2278

Poster Board II-255

Obesity has become a pandemic in the US, affecting both children and adults. In the adult population, evidence suggests that obesity has an adverse impact on outcomes of hematopoietic stem cell transplant for various malignancies. We investigated the influence of obesity on children undergoing unrelated cord blood transplant utilizing data from the Cord Blood Transplant Study. To our knowledge, no data exists on the effect obesity has on key prognostic indicators for cord blood transplant for malignant diseases in children. There were 191 patients '18 years of age with malignant diseases prospectively enrolled on a National Heart Lung Blood Institute (NHLBI) sponsored cord blood transplant study between 1999 and 2003. Data set was obtained after signed agreement with the NHLBI and local IRB approval. All patients received myeloablative preparative regimens with either total body irradiation and cyclophosphamide (N=172) or busulfan and melphalan (N=19). In addition, all patients received anti-thymocyte globulin as part of their conditioning regimens. Graft versus host disease (GVHD) prophylaxis included cyclosporine and prednisone. Children were classified into groups according to body mass index (BMI) percentile. Normal weight was defined as BMI between the 5^th and 85^th percentile, overweight between the 85^th and 95^th percentile, obesity above 95^th percentile for age and gender according to the Center for Disease Control and Prevention (CDC) guidelines. For the overall survival (OS) and disease free survival (DFS), the Cox regression model was used to test the effect of BMI while controlling for age, gender, performance status (<90 versus ≥90), HLA match (≤4/6 versus ≥5/6 HLA match), total nucleated cell count (TNC) per kg infused and CMV status. For neutrophil and platelet engraftment, transplant related mortality (TRM), grade II-IV acute GVHD, and chronic GVHD, competing risks regression analyses were used to test effect of BMI while controlling for other covariates. The median age was 7.59 years (range 2.07 – 17.90) with 113 (59%) male. 160 patients (84%) had a performance status of ≥90. 51 patients (27%) had acute myelogenous leukemia (AML), 109 patients (57%) had acute lymphoblastic leukemia (ALL) and 30 patients (16%) had other malignant diseases. 119 patients (62%) received a cord blood unit matched at 3/6 or 4/6 HLA antigens and 72 patients (38%) received a cord blood unit matched at 5/6 or 6/6 HLA antigens. The median TNC per kg infused was 5.2 × 10⁷/kg (range 0.15-80.9 × 10⁷/kg). Of the 191 total patients who were classified by their BMI percentiles, 117 patients (61%) were normal weight, 35 patients (18%) were overweight and 39 patients (20%) were obese. The two groups were not significantly different in sex distribution (p=0.25), diagnosis (p=0.13), performance status (p=0.91), median TNC received (p=0.49) or CMV status (p=0.47). Obese patients were significantly younger with a median age of 5.7 years compared to 8.9 years in normal weight children (p=0.002). Time to neutrophil and platelet engraftment, TRM, risk of grade II-IV acute GVHD, DFS and OS were not significantly different in overweight or obese patients compared to normal weight patients. There was a trend towards increased risk of chronic GVHD in obese patients (p=0.045) compared to normal weight patients. In conclusion, obesity has no significant effect on multiple outcomes after unrelated cord blood transplant in children with malignant diseases.