Rising Prevalence of Central Nervous System Involvement in Multiple Myeloma: A 2012-2020 National Inpatient Sample...

Central nervous system involvement in multiple myeloma (CNS-MM) is a rare but aggressive extramedullary manifestation occurring in approximately 1% of multiple myeloma (MM) patients. CNS-MM is associated with poor prognosis, with median survival ranging from 2 to 7 months. Small studies have suggested that advances in MM treatment may be leading to increasing prevalence of CNS-MM; however, a comprehensive analysis of temporal trends is lacking.

We conducted an epidemiological study of the 2012-2020 National Inpatient Sample, an all-payer database of US inpatient hospital admissions. Patients aged 18 and older with both MM and secondary CNS neoplasms were identified using ICD-9 and ICD-10 diagnosis codes. We then calculated weighted prevalence estimates and assessed them using regression analysis.

CNS-MM prevalence increased significantly, increasing by 166% from 2012 to 2020 (P < .001). This increase outpaced the 29% rise in overall MM prevalence (P < .001) during the same period. We observed no significant changes in mortality or discharge outcomes over time. Patients who were white (P < .05) and had income over median (P < .01) received more CNS-targeting diagnostic or therapeutic care, but we found no evidence of improved inpatient survival due to these procedures (P = .70) after adjusting for disease severity.

The prevalence of CNS-MM has grown to 2%-3% of MM patients since 2020, with stable rates of mortality despite interventions. Further investigation is needed to explore underlying mechanisms of this growth and improve outcomes.