Abstract / Summary
The International Metabolic Prognostic Index (IMPI) optimizes risk stratification for DLBCL relative to conventional IPI. Nevertheless, the original IMPI was derived from clinical trial data, so its performance in real-world populations is uncertain. Additionally, the original model did not incorporate LDH, resulting in insufficient evidence for direct comparison with NCCN-IPI. This study aimed to compare the prognostic performance of IMPI and NCCN-IPI in real-world DLBCL patients. A total of 294 newly diagnosed DLBCL patients treated with first-line R-CHOP were included in this retrospective cohort. TMTV was calculated using SUV ≥ 4 and a semi-automatic 41% SUVmax cutoff (TMTV41%). Patients were classified into four categorical IMPI subgroups and three continuous IMPI risk strata. Three-year TTP, PFS and OS were compared between IMPI and NCCN-IPI grouping systems. Model discrimination was evaluated using AIC and Harrell’s c-index. Within NCCN-IPI low, low-intermediate and high-intermediate populations, patients upgraded to higher risk by IMPI presented worse TTP, PFS and OS. Individual non-significant differences existed for TTP (low-risk group) and OS (low-intermediate-risk group). No survival improvement was observed in NCCN-IPI high-risk patients downgraded by IMPI. For TTP and PFS, categorical and continuous IMPI had numerically higher c-index and lower AIC values. For OS, only categorical and continuous exploratory IMPI41% displayed preferable numerical indicators, with continuous IMPI41% showing the best numerical performance across all models. This retrospective real-world study indicates that IMPI, especially the exploratory IMPI41%, may supply additional prognostic stratification for NCCN-IPI low-, low-intermediate-, and high-intermediate-risk patients. It cannot be confirmed that these screened high-risk subgroups benefit from early intensive treatment. The present findings need external validation in larger independent cohorts. The research protocol of this study was approved by the Ethics Committee of Jiangsu Cancer Hospital (Approval KY-2025-095, approval date: 16 July 2025).