Background/Purpose: Idiopathic Inflammatory Myopathies (IIM), including polymyositis and dermatomyositis, are rare systemic autoimmune disorders characterized by chronic muscle inflammation and progressive muscle weakness. Patients with IIM are at an elevated risk of fractures due to a combination of factors, including prolonged corticosteroid use, reduced bone mineral density, impaired mobility, and an increased propensity for falls. Although fracture risk in IIM is well recognized, there is limited understanding of how IIM affects hospitalization outcomes following fractures, including resource utilization, discharge disposition, and mortality. Clarifying these associations is essential to inform clinical management and optimize care strategies for this high-risk patient population. To evaluate the impact of Idiopathic Inflammatory Myopathies (IIM) on hospitalization outcomes among adults admitted with fractures by comparing demographic characteristics, comorbidity burden, resource utilization, and in-hospital mortality between patients with and without IIM using a nationally representative dataset.

Methods: We conducted a retrospective cohort study using the National Inpatient Sample (NIS) data from 2017 to 2022. Adults (≥18 years) hospitalized with a primary diagnosis of fracture were identified and further stratified based on the presence or absence of a secondary diagnosis of IIM which includes polymyositis , dermatomyositis and Inclusion body myositis. using ICD-10 Codes. Patient demographics, comorbidities, fracture types, length of stay (LOS), total hospital charges, discharge disposition, and in-hospital mortality were compared between groups. Multivariable logistic and linear regression models, adjusting for demographic and clinical variables, were used to assess the independent association of IIM with hospitalization outcomes. Adjusted odds ratios (aOR), β coefficients, 95% confidence intervals (CI), and P-values were reported.

Results: Among 5,273,033 fracture hospitalizations, 1,950 (0.04%) had a concurrent diagnosis of IIM. Compared to patients without IIM, those with IIM were older (mean age 72.1 vs. 69.5 years, p < 0.001) and more likely to be female (73.08% vs. 58.13%, p < 0.001). Osteoporosis (24% vs. 11%, p < 0.001) and steroid use (23.27% vs. 1.3%, p < 0.001) were significantly more prevalent among IIM patients. After multivariable adjustment, IIM was associated with a significantly longer hospital stay (β = +0.49 days, 95% CI 0.20–0.60, p = 0.029) and higher total hospital charges (β = +$4,877, 95% CI $1,156–$4,655, p = 0.037). No significant differences were observed in in-hospital mortality (aOR 1.29, 95% CI 0.60–2.70, p = 0.505) or discharge to skilled nursing facilities (aOR 0.91, 95% CI 0.73–1.14, p = 0.408).

Conclusion: Among adults hospitalized for fractures, the presence of IIM was associated with longer hospital stays and higher healthcare costs but was not associated with increased in-hospital mortality or skilled nursing facility disposition. These findings underscore the importance of proactive fracture prevention strategies, interdisciplinary peri-fracture management, and early rehabilitation planning in patients with IIM.

Patient Demographics and Hospitalization Characteristics

Multivariable Regression Analysis for Adjusted Outcomes

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/characterization-of-hospitalization-patient-demographics-and-impact-of-idiopathic-inflammatory-myopathies-on-hospitalization-outcomes-in-adult-fracture-patients-a-national-inpatient-sample-analysis/