Predictive Factors for Hospitalization After Outpatient Reduced-Intensity Conditioning (RIC) Allogeneic Hematopoietic Progenitor Cell Transplantation (AHPCT)

Although RIC AHPCT can be performed as an outpatient, many pts who receive this therapy still are later hospitalized. An assessment of predictive factors prior to transplant would be useful to help develop strategies to reduce hospitalizations after outpatient RIC AHPCT as well as to counsel pts further regarding post-transplant risk. We retrospectively evaluated 132 consecutive adult pts with hematologic diseases who received RIC AHPCT at our institution from 1/2000-12/2009. Pts received fludarabine and either 200 cGy (N = 45) or 400 cGy (N = 87) TBI. GVHD prophylaxis: mycophenolate and either cyclosporine for those with related donors (N = 79) or tacrolimus for those with unrelated donors (N = 53). Median age was 57 years (range, 18-70) and 78 were males. Diagnoses included 73 myeloid and 55 lymphoid malignancies and 4 hematologic diseases. 92 had no HLA disparate donor, 12 had an HLA disparity at HLA-A, B, C or DRB1 (major), and 28 had an HLA disparity at HLA-DQ or DP (minor). CIBMTR comorbidity index (CI): 51 low, 43 intermediate and 38 high risk pts. 120 (90%) were hospitalized post transplant at a median of 14 days (range, day 0 to +475) and the most common reasons were: 72 fevers, 46 infections and 19 acute GVHD. Risk factors for hospitalization were assessed by Cox proportional hazards analysis. Variables included gender, age, CI, no. prior chemotherapies, prior radiation, diagnosis, TBI dose, donor relationship, HLA disparities, TNC/CD34+ doses and time of transplant relative to the 1st one on 1/10/00. From the univariable analysis the no. of prior chemotherapies, TBI dose, unrelated donor and HLA disparity were associated with an increased risk for hospitalization, while a larger TNC dose was associated with a lower risk. In multivariable analysis 2 variables remained prognostic: 400 cGy TBI (p = 0.026) and HLA disparity [minor/none; p < 0.001; major/none; p = 0.07]. Although the majority of pts received 400 cGy TBI, we previously did not find a difference in time to neutrophil engraftment compared to those receiving 200 cGy TBI (Sobecks et al. BMT 2008;42:715-22). We conclude that HLA disparities and 400 cGy TBI may delay immune reconstitution resulting in more infections that require hospitalization after RIC AHPCT. Future strategies to enhance immune reconstitution after this approach are warranted and if effective may have important implications regarding reductions in expenses and healthcare resources associated with inpatient hospitalization.