Predictors of Hospitalization, Length of Stay, and Cost of Care Among Adults With Dermatomyositis in the United States.

OBJECTIVE: To determine the prevalence and risk factors for hospitalization with dermatomyositis and assess inpatient burden of dermatomyositis. METHODS: Data on 72,651,487 hospitalizations from the 2002-2012 Nationwide Inpatient Sample, a 20% stratified sample of all acute-care hospitalizations in the US, were analyzed. International Classification of Diseases, Ninth Revision, Clinical Modification coding was used to identify hospitalizations with a diagnosis of dermatomyositis. RESULTS: There were 9,687 and 43,188 weighted admissions with a primary or secondary diagnosis of dermatomyositis, respectively. In multivariable logistic regression models with stepwise selection, female sex (logistic regression: adjusted odds ratio 2.05 [95% confidence interval (95% CI) 1.80, 2.34]), nonwhite race (African American: 1.68 [1.57, 1.79]; Hispanic: 2.38 [2.22, 2.55]; Asian: 1.54 [1.32, 1.81]; and multiracial/other: 1.65 [1.45, 1.88]), and multiple chronic conditions (2-5: 2.39 [2.20, 2.60] and ≥6: 2.80 [2.56, 3.07]) were all associated with higher rates of hospitalization for dermatomyositis. The weighted total length of stay (LOS) and inflation-adjusted cost of care for patients with a primary inpatient diagnosis of dermatomyositis was 80,686 days and $168,076,970, with geometric means of 5.38 (95% CI 5.08, 5.71) and $11,682 (95% CI $11,013, $12,392), respectively. LOS and costs of hospitalization were significantly higher in patients with dermatomyositis compared to those without. Notably, race/ethnicity was associated with increased LOS (log-linear regression: adjusted ß [95% CI] for African American: 0.14 [0.04, 0.25] and Asian: 0.38 [0.22, 0.55]) and cost of care (Asian: 0.51 [0.36, 0.67]). CONCLUSION: There is a significant and increasing inpatient burden for dermatomyositis in the US. There appear to be racial differences, as nonwhites have higher prevalence of admission, increased LOS, and cost of care.