Montalbán, CarlosDíaz-López, AntonioDlouhy, IvanRovira, JordinaLopez-Guillermo, ArmandoAlonso, SaraMartín, AlejandroSancho, Juan MGarcía, OlgaSánchez, Jose MRodríguez, MarioNovelli, SilvanaSalar, AntonioGutiérrez, AntonioRodríguez-Salazar, Maria JBastos, MarianaDomínguez, Juan FFernández, RubénGonzalez de Villambrosia, SoniaQueizan, José ACórdoba, Raulde Oña, RaquelLópez-Hernandez, AndrésFreue, Julian MGarrote, HeidysLópez, LourdesMartin-Moreno, Ana MRodriguez, JoseAbraira, VíctorGarcía, Juan FGELTAMO-IPI Project Investigators2023-01-252023-01-252017-01-20http://hdl.handle.net/10668/10794The study included 1848 diffuse large B-cell lymphoma (DLBCL)patients treated with chemotherapy/rituximab. The aims were to validate the National Comprehensive Cancer Network International Prognostic Index (NCCN-IPI) and explore the effect of adding high Beta-2 microglobulin (β2M), primary extranodal presentation and intense treatment to the NCCN-IPI variables in order to develop an improved index. Comparing survival curves, NCCN-IPI discriminated better than IPI, separating four risk groups with 5-year overall survival rates of 93%, 83%, 67% and 49%, but failing to identify a true high-risk population. For the second aim the series was split into training and validation cohorts: in the former the multivariate model identified age, lactate dehydrogenase, Eastern Cooperative Oncology Group performance status, Stage III-IV, and β2M as independently significant, whereas the NCCN-IPI-selected extranodal sites, primary extranodal presentation and intense treatments were not. These results were confirmed in the validation cohort. The Grupo Español de Linfomas/Trasplante de Médula ósea (GELTAMO)-IPI developed here, with 7 points, significantly separated four risk groups (0, 1-3, 4 or ≥5 points) with 11%, 58%, 17% and 14% of patients, and 5-year overall survival rates of 93%, 79%, 66% and 39%, respectively. In the comparison GELTAMO IPI discriminated better than the NCCN-IPI. In conclusion, GELTAMO-IPI is more accurate than the NCCN-IPI and has statistical and practical advantages in that the better discrimination identifies an authentic high-risk group and is not influenced by primary extranodal presentation or treatments of different intensity.enDLBCLprognostic scoresrisk assessmentAdultAgedAged, 80 and overAntineoplastic Combined Chemotherapy ProtocolsBiomarkersFemaleFollow-Up StudiesHumansKaplan-Meier EstimateLymphoma, Large B-Cell, DiffuseMaleMiddle AgedNeoplasm StagingPrognosisRemission InductionReproducibility of ResultsTreatment Outcomebeta 2-Microglobulinresearch article28106247open access10.1111/bjh.144891365-2141https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/bjh.14489