International Myeloma Working Group updated criteria for the diagnosis of multiple myeloma
- Study type
- Clinical guideline
- Study name
- IMWG 2014
- Design
- Consensus guideline of the International Myeloma Working Group (IMWG)
- Source
- Lancet Oncol · 2014
In plain words
These criteria set out when a plasma cell disorder counts as "active myeloma" that needs treatment. In the past, treatment was started only once damage to the bones, kidneys or blood, or a raised calcium level, had appeared. Under these criteria, if any of three specific very-high-risk markers is found, the disease counts as active myeloma even before any damage has happened, and it is treated to prevent that damage.
Key guideline recommendations
- IMWG consensus
Definition of multiple myeloma: clonal bone marrow plasma cells of at least 10% or a biopsy-proven bony or extramedullary plasmacytoma, plus at least one myeloma-defining event (CRAB or one of the SLiM biomarkers).
- IMWG consensus
CRAB features: hypercalcaemia (serum calcium more than 1 mg/dL above the upper limit of normal or more than 11 mg/dL); renal insufficiency (creatinine clearance less than 40 mL/min or serum creatinine more than 2 mg/dL); anaemia (haemoglobin more than 2 g/dL below the lower limit of normal or less than 10 g/dL); bone lesions (one or more lytic lesions on radiography, CT or PET-CT).
- IMWG consensus
Myeloma-defining biomarkers (SLiM): clonal bone marrow plasma cells 60% or more; involved:uninvolved serum free light chain ratio 100 or more (with the involved light chain at least 100 mg/L); more than one focal lesion on MRI.
- IMWG consensus
Smouldering myeloma: serum monoclonal protein (IgG or IgA) of at least 3 g/dL or urinary monoclonal protein of at least 500 mg per 24 hours and/or clonal bone marrow plasma cells 10 to 60%, without myeloma-defining events or amyloidosis.
Study population
Patients with a monoclonal plasma cell gammopathy; definitions of active multiple myeloma and smouldering myeloma, and the criteria for myeloma-defining events.
Clinical significance and place in guidelines
The IMWG 2014 criteria (CRAB plus the "SLiM" biomarkers) are the global reference for diagnosing multiple myeloma and are used in the EHA-EMN and NCCN guidelines and in all current trials. For treatment, the evidence-based EHA-EMN guideline (Nat Rev Clin Oncol 2025; doi:10.1038/s41571-025-01041-x) has been published, covering quadruplet regimens and the new immunotherapies; its full text was not available when this card was prepared.
Limitations
This guideline covers diagnostic criteria and makes no treatment recommendations. The full text was not available for this summary; the numerical thresholds of the criteria were checked against their reproduction in open-access sources, and for clinical use the original table of the paper should be consulted.
This summary was prepared by the editorial team from the published paper; the original paper is the final reference. Read the original abstract on PubMed.