Sars-Cov-2 and Multiple Myeloma Results from the National Inpatient Sample

Background & aims

Multiple myeloma (MM) is a plasma cell dyscrasia characterized by the uncontrolled proliferation of plasma cells producing a monoclonal immunoglobulin. Infection is a common complication in multiple myeloma patients due to immune dysfunction caused by hypogammaglobulinemia, decreased lymphocyte function, and suppression of normal plasma cell activity. Moreover, skeletal pain from pathologic fractures in the ribs or the spine can cause hypoventilation, increasing the risk of pneumonia. SARS-CoV-2 infection in patients with MM is associated with a significant increase in mortality. This analysis aims to trend the mortality of MM over the pre and post vaccination era.

Materials and methods

The National Inpatient Sample (NIS) was searched for the study population from January 2020 to December 2021. Adults above (age ≥ 18 years) with Multiple myeloma hospitalized with a primary diagnosis of SARS-CoV-2 were identified using the ICD 10 code. The primary outcomes were in-hospital mortality. Secondary outcomes include length of stay and cost. Logistic regression was used to measure the primary outcome of mortality, and linear regression for secondary outcomes of LOS and hospital charges. Chi-square analysis was used to analyze the significance of demographic observations with a cutoff P-value of 0.5.

Results

In 2020, there were 3,045 patients with multiple myeloma who contracted COVID-19, while in 2021, the number increased to 4,355. Characteristics of MM patients were compared to non-MM patients, who were 1,047,000 patients in 2020 and 1,518,676 in 2021The vast majority of patients were over the age of 65, with 72.58% of MM patients being over 65 in 2020, compared to 71.87% in 2021. There was no significant change in the mortality among MM patients; mortality was 18.72% in 2020, compared to 18.51% in 2021. For non-MM patients, mortality was 11.15% in 2020 and 11.31% in 2021, with a P value of 0.000. The mean length of stay for MM patients was 8.14 days in 2020 compared to 9.61 days in 2021. Meanwhile, for non-MM, the length of stay was 7.48 days in 2020 and 7.97 in 2021, with a P value of 0.002. The mean Charlson index per year was high in the myeloma group, 4.25 in 2020 and 4.29 in 2021with a P value of 0.687. The mean Charlson score was much lower for non-MM patients, 1.85 in 2020 and 1.63 in 2021, with a P value of 0.000.

Discussion and Conclusion

Since the first wave of COVID-19, several measures have been implemented to reduce the severity and transmission of the virus. The first vaccine became available in December 2020. Despite these efforts, the analysis did not show significant changes in the mortality of SARS-CoV-2 infection in patients with MM during 2020 and 2021. Similarly, there was no significant change in the mortality rate in non-MM patients over the two years. However, there was a slight increase in the length of stay in 2021 compared to 2020. Due to data limitation, it is difficult to attribute the lack of change in mortality in the post-vaccination era to the poor immune response to the vaccine, despite the fact that several studies pointed out that the antibody response in multiple myeloma patients to SARS-CoV-2 vaccines is suboptimal. Another limitation is the lack of accurate data regarding the predominant strain of strain SARS-CoV-2 in 2020 and 2021, which might affect the severity of the disease and mortality. Additional major limitation is the effect of COVID-19 treatment on mortality. Overall, The analysis suggests that the mortality of MM remains stable in the pre and post-vaccination era. More elaborative studies are needed to assess risk factors associated with mortality in MM patients with SARS-CoV-2 infection.

No relevant conflicts of interest to declare.