All-cause hospitalizations and mortality in systemic lupus erythematosus in the US: results from a national inpatient database

Systemic lupus erythematosus (SLE) is a multisystem disorder. While several studies have outlined risk factors for hospitalization and mortality in SLE; the frequency of hospitalizations from various causes has varied among studies and over the years. We aimed to assess the causes of SLE hospitalizations and inpatient mortality compared to those without SLE in the United States in a recent year (2016) using a large national inpatient database. We used National Inpatient Sample (NIS) to identify hospitalizations with SLE using the ICD-10 code M32. Among hospitalizations with SLE as secondary diagnosis, we used ICD-10 codes to assess the primary diagnoses associated with hospitalizations and mortality. Our study included 174,105 SLE hospitalizations matched to controls (similar age, sex, and NIS stratum) in the year 2016. Mean age of hospitalization with SLE was 51.82 years, and 89% of hospitalized SLE patients were females. Mean length of stay, cost and mortality for SLE were 5.6 +/- 7.2 days, US $ 14,450 and 1.96%, respectively. SLE was the primary diagnosis in 10,185 (5.85%) of all SLE related hospitalizations. Among SLE hospitalizations, infection was the most common primary diagnosis (15.80%) followed by cardiac and renal manifestations (7.03% and 4.91% respectively). Infection was the leading cause of mortality (38.18%) followed by cardiac manifestations (12.04%). Infections and cardiac involvement were the leading causes of hospitalizations and in-hospital mortality in SLE. Whether this is related to the disease itself, its associated comorbidities or immunosuppressive agents would require further studies.