Impact of diabetes mellitus on inpatient outcomes among hospitalized patients with multiple myeloma: A National Inpatient Sample analysis (2018–2020).

Abstract

e19540 Background: Diabetes mellitus (DM) is common in patients with multiple myeloma (MM). While DM is often perceived as a significant risk factor for complications, its independent impact after adjusting for key comorbidities particularly renal and cardiovascular disease is not well defined. We evaluated whether DM status independently influences in-hospital mortality and resource utilization or if these outcomes are primarily driven by other comorbid conditions. Methods: We conducted a retrospective cohort study using the National Inpatient Sample (2018–2020). Adult hospitalizations with multiple myeloma (MM) were stratified by diabetes mellitus (DM) status. Primary outcomes were in-hospital all-cause mortality, length of stay (LOS), and inflation adjusted total hospital charges (THC). Secondary outcomes included acute kidney injury (AKI), venous thromboembolism (VTE), sepsis, respiratory failure, and requirement for mechanical ventilation. Survey-weighted multivariable regression models adjusted for demographics, comorbidities, hospital characteristics, and illness severity were used to assess associations between DM and inpatient outcomes. Results: Among 62,870 MM hospitalizations, 13,980 (22.2%) had comorbid DM. Patients with DM were older (median 68 vs 65 years, p<0.001), more frequently male (58% vs 55%, p=0.003) and had a higher baseline prevalence of hypertension (HTN) (57% vs 84%, p<0.001) and chronic kidney disease (CKD) (40% vs 26%, p<0.001). DM was not independently associated with the primary outcomes of mortality (aOR 0.87, p=0.2), length of stay (p=0.7), or inflation adjusted THC (p=0.4). Regarding secondary outcomes, DM status was not independently associated with AKI (aOR 0.95, p=0.4), sepsis (aOR 1.06, p=0.6), respiratory failure (aOR 0.93, p=0.4), or mechanical ventilation (aOR 1.00, p>0.9). A borderline lower risk of VTE was observed (aOR 0.79, 95% CI 0.62–1.00, p=0.053). Notably, the risk for adverse outcomes was strongly driven by other comorbid factors such as pre-existing HTN, CKD, hyperlipidemia, coronary artery disease (CAD), obesity and heart failure whereas DM was only a borderline independent risk factor for VTE after multivariable adjustment. Conclusions: In hospitalized patients with multiple myeloma, diabetes mellitus does not independently worsen short-term mortality, clinical complications, or healthcare utilization. The elevated risks observed in this population are comorbidity-dependent rather than DM-specific. These findings suggest that inpatient management should focus on the optimization of concurrent conditions specifically renal impairment, cardiovascular disease and obesity as these are the true drivers of adverse outcomes in MM hospitalizations.