Changes in Hospitalization and Infection Burden in Patients with Multiple Myeloma Before and During the COVID-19 Pandemic

Background: The increasing incidence and improved survival rates of multiple myeloma (MM) have led to a growing healthcare burden, particularly in terms of hospitalizations. In addition, infection-related complications remain a major cause of morbidity and mortality in these patients. The impact of infection control measures implemented during the COVID-19 pandemic on hospitalization patterns in MM is not well-established. Methods: We conducted a retrospective observational study including all hospital admissions of patients with MM in a tertiary hospital in Spain across three different periods: 2008, 2018, and May 2020 to April 2021 (COVID-19 pandemic period). We analyzed the proportion of admissions, cumulative length of stay, causes of hospitalization, and infection-related complications. Results: The proportion of hospitalizations due to MM increased significantly from 14% in 2008 to 29.8% in 2018 (p < 0.001), along with a parallel increase in cumulative length of stay (14.4% vs. 27.1%, p < 0.001). During the COVID-19 period, a significant reduction in the proportion of admissions was observed compared to 2018 (21.2% vs. 29.8%, p = 0.0029), while cumulative length of stay showed a non-significant decrease. The proportion of infection-related admissions remained stable during the pandemic period, although the absolute number of infections decreased, including respiratory infections. Notably, the incidence of nosocomial pneumonia decreased significantly (26.3% vs. 9.6%, p = 0.028). Conclusions: Compared with 2008, patients with MM accounted for a substantially higher proportion of hospital admissions and cumulative hospital stay in 2018, reflecting the increasing healthcare burden associated with this disease. During the COVID-19 period, a significant reduction in nosocomial pneumonia was observed, suggesting that infection-control strategies may help reduce respiratory complications in patients with MM.