Concordance and prognostic value of bone–marrow MRD and PET–CT in multiple myeloma: a systematic review and meta–analysis

Background: Bone-marrow minimal residual disease (MRD) and positron emission tomography/computed tomography (PET-CT) are central to response assessment in multiple myeloma (MM); however, their agreement, discordant patterns, and how their joint results relate to progression-free survival have not been systematically quantified. Methods: vs all other combinations) on PFS. We used random-effects models (REML with Hartung-Knapp adjustment) to estimate pooled hazard ratios for PFS. Sensitivity analyses were informed by QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies 2) and QUIPS (Quality in Prognosis Studies) risk-of-bias assessments. This study was registered with Open Science Framework (OSF; DOI 10.17605/OSF.IO/3CH9E). Findings: 27%; k = 5). Interpretation: MRD and PET-CT interrogate distinct but complementary disease compartments, yielding low statistical concordance yet strong joint prognostic value. Dual MRD/PET-CT negativity reproducibly identifies a low-risk subgroup, whereas discordant patterns capture biologically heterogeneous residual disease. Prospective myeloma trials should prespecify all four MRD/PET-CT categories, align assessment timing and thresholds, and routinely report concordance and discordance to enable response-adapted treatment. Funding: None.