(B-016) Trends in the Incidence of Monoclonal Gammopathy of Undetermined Significance (MGUS) Before and During the COVID-19 Pandemic

Background: Prior infection with certain viruses could accelerate the clonal proliferation of plasma cells, leading to the development of plasma cell dyscrasias like MGUS, a precursor to multiple myeloma. The COVID-19 pandemic offered a unique opportunity to explore the relationship between SARS-CoV-2 infection and the incidence of MGUS.

Objectives: To evaluate population level trends in MGUS incidence in the US before and during the COVID-19 pandemic.

Methods: New cases of MGUS from Jan 1, 2017, to Dec 31, 2022, in Komodo closed claims were identified as ≥1 inpatient or ≥2 outpatient MGUS diagnoses and within 90 days of the 1st MGUS diagnosis: ≥1 protein electrophoresis, ≥1 immunofixation test, and ≥1 hematologist/oncologist visit (index date=date all criteria met). Patients were required to be continuously enrolled in pharmacy and medical benefits in ≥1 year prior to the first MGUS diagnosis (i.e., baseline). Patients with multiple myeloma, light chain amyloidosis, other hematologic cancers, or a history of stem cell transplant, CAR-T therapy, or anti-multiple myeloma therapy during baseline were excluded. MGUS incidence per 100,000 was calculated as the number of incident MGUS cases divided by the number at risk at the beginning of each interval. Monthly and yearly MGUS incidence was estimated for patients aged < 50 vs. ≥50 years and by sex.

Results: We identified 32,853 incident MGUS cases; demographics were consistent across the study period; annually, 66-70% were aged ≥60 years, 53-57% were women, and 54-58% were White. The yearly incidence of MGUS remained stable during 2017-2019 (range 6.3 to 6.4 cases per 100,000). MGUS incidence declined in 2020 (5.9 per 100,000) especially in April, May, and June (0.28, 0.37, and 0.43 per 100,000, respectively). During 2021, the incidence increased to 6.7 per 100,000 and returned to the pre-pandemic levels (6.3 per 100,000) during 2022. Trends were similar by sex but were less pronounced for those aged < 50 years.

Conclusions: During the early months of the pandemic, there was a drop in MGUS incidence, followed by a rebound in 2021, likely due to the resumption of screening and healthcare-seeking behaviors. By 2022, the incidence of MGUS returned to pre-pandemic levels. While an increase in MGUS incidence was not observed in this study, given the potential latency period, longer follow-up may be required to evaluate the true impact of SARS-CoV-2 on the development of MGUS.