Increased risk of infections in smoldering multiple myeloma: results from the screened iStopMM study

Area of Science:

• Hematology
• Oncology
• Infectious Diseases

Background:

• Multiple myeloma (MM) is a significant cause of morbidity and mortality, with infection risk elevated in precursor conditions.
• Monoclonal gammopathy of undetermined significance (MGUS) is known to increase infection risk, but data for smoldering multiple myeloma (SMM) are limited.

Purpose of the Study:

• To investigate and quantify the infection risk in individuals diagnosed with smoldering multiple myeloma (SMM).
• To compare infection rates in SMM patients against both MGUS patients and individuals without MM precursors.

Main Methods:

• Utilized data from the iStopMM study, screening 75,422 Icelandic individuals aged ≥40 years.
• Matched SMM patients (n=188) with MGUS patients (n=188) and MGUS-free comparators (n=810) by age and sex.
• Analyzed infection outcomes using nationwide registries (ICD-10 codes, antimicrobial prescriptions) and Cox proportional hazards models, adjusting for immunoparesis.

Main Results:

• Individuals with SMM exhibited significantly higher rates of infections (HR 1.36) and antibacterial prescriptions (HR 1.24) compared to comparators.
• SMM patients also showed an increased risk of infections compared to MGUS patients (HR 1.37).
• Adjustment for immunoparesis partially attenuated these associations, suggesting its role in mediating infection risk.

Conclusions:

• This study demonstrates a significantly increased infection risk in SMM patients compared to both MGUS and individuals without MM precursors.
• The findings suggest an underrecognized burden of infections in the smoldering multiple myeloma population.
• These results underscore the importance of monitoring and managing infection risk in SMM patients.