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

ObjectiveTo determine the prevalence and risk factors for hospitalization with dermatomyositis and assess inpatient burden of dermatomyositis. MethodsData 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. ResultsThere 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 [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]). ConclusionThere 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.