The Predictive Value of the Hematopoietic Cell Transplantation (HCT)-Specific Comorbidity Index (CI) in Recipients of Umbilical Cord Blood (UCB) Transplantation.

The hematopoietic cell transplantation (HCT)-specific comorbidity index (CI) has been shown to predict nonrelapse mortality (NRM) and overall survival (OS) after sibling and unrelated adult volunteer donor transplantation (Sorror Blood 2005, 106:2912). We retrospectively studied the predictive value of the HCT-CI in a cohort of 182 patients who underwent an umbilical cord blood (UCB) transplant for advanced or high risk malignancy at the University of Minnesota, between August 2001 and May 2006. Patients receive either a myeloablative (MA, n=54) or nonmyeloablative (NST, n=128) conditioning regimens followed by cyclosporine and mycophenolate mofetil in both groups. Patients received single (n=27) or double (n=155) UCB grafts that were HLA-matched 4–6/6 matched to the recipient, and for double UCB grafts 4–6/6 matched each other as well. All received G-CSF from day 0 to ANC > 2500 for three days. Antibiotic prophylaxis, blood products, and growth factor administration followed the same institutional guidelines. Patients’ median age was 47 (range: 18–69), median weight 78 kg (r: 45–149), and 51% were CMV seropositive. Thirty patients, all in the NST group, had prior autologous transplant. HCT-CI scores were assigned retrospectively; scores were zero (n=18%), 1–2 (n=33%), or >2 (n=49%) and were comparable between the MA and NST groups. The median nucleated cell dose (NCD) was 3.5 X 107/kg (range: 1.1–6.8) and CD34+ cell dose was 4.7 X 105/kg (range: 0.7–18.8) with no difference in recipients of singles and double UCB grafts or MA and NST conditioning regimens. The NRM at 1-year was 13% (95%CI, 2–24) for patients with HCT-CI score of zero, 20% (95%CI, 10–30) for scores 1–2, and 22% (95%CI, 14–30) for score > 2 (p=.46). In multivariate regression model, HCT-CI score was not an independent predictor of NRM [HCT-CI score Zero RR 1(ref), 1–2 RR 1.5 (95%CI, 0.5–4.5, p=.5; >2 RR 1.8 (95%CI, 0.6–5.3), p=.27], whereas patients who received a NST conditioning had significantly lower relative risk (RR) of NRM (RR 0.5, 95%CI, 0.2–1.0, p=.05). The 1-yr OS was 72% (95%CI, 53–84) for patients with score zero, 65% (95%CI, 52–76) for scores 1–2, and 56% (95%CI, 29–65) for scores >2. In Cox regression analysis the HCT-CI was not associated with the risk of death, in contrast to disease risk group, development of grades II–IV acute GVHD, and interval between diagnosis and transplantation (Table). While the HCT-CI was not predictive of either NRM nor OS in recipients of UCBT, high OS for the group as whole, patient numbers and selection procedures may explain, at least in part, these results. However, it is also possible that the HCT-CI scoring system may not yet be optimized and some medical conditions may have greater impact on HSC transplantation outcome as compared to others.