PURPOSE: The Hematopoietic Cell Transplantation-Comorbidity Index(HCT-CI) is a comorbidity score which has prognostic value in hematopoietic stem cell transplantation. As described by Sorror (Blood 2005; 106:2912) higher scores predict higher risk of mortality. Since spirometry and diffusion capacity represent important determinants of the HCT-CI, we reviewed patients at our center focusing on prediction equations for FEV1 and DLCO.
METHODS: We determined the HCT-CI score in all patients who underwent Matched Unrelated Donor transplantation in a single arm, single institution trial assessing efficacy of a 3-drug combination of cyclosporine, methotrexate and prednisone for GVHD prophylaxis from 1996-2006. Each individual comorbidity was obtained by retrospective chart review. Pulmonary comorbidity is defined by an FEV1 and/or DLCO as severe if ≤; 65% and intermediate if 65-80% of predicted. The individual FEV1 and DLCO values used for calculating percentage predicted FEV1 and DLCO were recalculated using the age and height at the time of the test as required by the Crapo equation. The use of prediction equations reported by Crapo for DLCO were compared with DLCO using equations described by Miller.
RESULTS: 150 consecutive patients with spirometry and DLCO data were available for the HCT-CI score. A systematic difference was detected between the two equations. The use of the different prediction equations changed the comorbidity scores and hence affected the mortality prognostication. Almost 50% of the individuals (N=73) had their DLCO percentage predicted lower using the Crapo formula rather than the Miller formula and hence classified as a more serious comorbidity.
CONCLUSION: Awareness of the significant impact of prediction equations on DLCO predicted values as well as the subsequent impact on the comorbidity score is critical to obtain accurate prognostication.
CLINICAL IMPLICATIONS: The HCT-CI score is gaining rapid acceptance in the transplant community, both for treatment allocation and for the design and analysis of clinical trials. As the main contributors to the HCT-CI score are pulmonary parameters, a clear understanding of the variables which influence it must be identified and normalized.
DISCLOSURE: Sai Haranath, No Financial Disclosure Information; No Product/Research Disclosure Information