Objective This study determines trends in demographics and hospitalization outcomes among patients admitted for systemic sclerosis (SScl) and evaluates the differences between comorbidities. Methods The study used data from the Nationwide Inpatient Sample (NIS) for the years 2010-2014. We identified SScl as the primary diagnosis and the associated medical and psychiatric comorbidities using validated International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes. The differences in comorbidities and in-hospital mortality were quantified using multinomial logistic regression (odds ratio (OR)). Results Inpatient admissions for SScl decreased over the period 2010-2014 by 15.9% (p < 0.001). There was an increasing trend in the 61-80 years age group as they had a 29% increase in admissions and a higher risk of in-hospital mortality (OR = 2.113; p = 0.020). The differences between races showed weaker linear trends, with Caucasians (57.5%) showing an increasing trend, and African Americans (24.3%) and Hispanics (11.8%) having a decreasing trend (p < 0.001). However, Hispanics had the highest risk of mortality (OR = 1.295; p = 0.001) during hospitalization. In-hospital mortality had a linear decreasing trend, with a 10.3% decrease in deaths in 2010, and a 9.1% decrease in 2014 (p < 0.001). Hypertension (47.3%), pulmonary circulation disorders (40.1%), pulmonary fibrosis (29.7%), and congestive heart failure (24.4%) constituted the majority of comorbidities. Comorbid diabetes increased the risk of in-hospital mortality in SScl patients by four times (OR = 3.914; p = 0.003). Esophageal reflux disorder was present in only 6.7% of SScl patients, but it increased the risk of in-hospital mortality (OR = 2.643: p < 0.001). Among psychiatric comorbidities, depression (OR = 1.526; p = 0.001) and psychosis (OR = 1.743; p = 0.039) both increased the risk of in-hospital mortality. Conclusion We observed the various comorbidities that were associated with substantial and significant differences in the risk of in-hospital mortality. We assert that these findings indicate that comorbid conditions are influential factors that must be considered in models of health-related quality of life (HRQOL) in SScl. More attention needs to be paid to the elderly population at risk of having a higher risk of inpatient death. Further research to guide the development of clinical care models for targeting early diagnosis and treatment of comorbidities in SScl is necessary to reduce both mortality and morbidity, as well as improve the quality of care for these patients.
Keywords: comorbidity; demographics; mortality risk; national inpatient sample; scleroderma; systemic sclerosis.