OBJECTIVES: This research estimated the real-world frequency of and healthcare resource use (HCRU) associated with health events during MM treatment. METHODS: MM patients initiating therapy between 01/01/2013-01/31/2016 were selected from the Inovalon Moreadministrative claims database. Health events were identified by reviewing safety information from MM treatment labels and registration trials. Patients with a diagnosis of an event during MM treatment were identified (cases). Events that occurred in ≥5% of patients were included in the analysis. HCRU was assessed during a 30-day interval following the event and compared (using chi-square statistic) to a 30-day interval following a shadow date for controls (patients who did not have the event and propensity-score matched to cases). Shadow dates were determined by adding the number of days from treatment start date to event date among cases to the treatment start date among controls. RESULTS: Among 775 MM patients, 25 events were included in the analysis. Over the course of MM treatment, 80.8% had a claim for bortezomib, 58.3% for lenalidomide, 25.6% for cyclophosphamide, 7.2% for melphalan, 5.3% for carfilzomib, 4.7% for pomalidomide. The proportion of patients with an event ranged 5.2%-19.0%. The 5 most common events were: asthenia/fatigue (19.0%), dehydration (17.7%), nausea (17.2%), constipation (13.2%), hypokalemia (12.8%). The proportion of inpatient admissions observed among patients with an event ranged 17.7%-82.6% vs 3.8%-18.3% among controls. Inpatient admissions were most commonly observed among patients with sepsis (82.6% vs 8.7%), confusion (78.4% vs 10.8%), hyponatremia (68.9% vs 6.7%), pneumonia (68.5% vs 5.6%), and hyperkalemia (63.3% vs 8.2%) for cases vs controls, respectively; p<0.0001 for all. CONCLUSIONS: This study suggests that health events during the course of MM treatment occur frequently and with significant HCRU potentially imposing a substantial burden to patients and the healthcare system. Use of newer MM treatments with improved clinical profiles may help to reduce this burden.