The rate of and risk factors for frequent hospitalization in systemic lupus erythematosus: results from the Korean lupus network registry

Objectives The survival rate of patients with systemic lupus erythematosus has improved in the last few decades, but the rate of hospitalization and health care costs for these patients remain higher than in the general population. Thus, we evaluated the rate of hospitalization and associated risk factors in an inception cohort of Korean patients with lupus. Methods Of the 507 patients with systemic lupus erythematosus enrolled in the KORean lupus NETwork, we investigated an inception cohort consisting of 196 patients with systemic lupus erythematosus presenting within 6 months of diagnosis based on the American College of Rheumatology classification criteria. We evaluated the causes of hospitalization, demographic characteristics, and laboratory and clinical data at the time of systemic lupus erythematosus diagnosis of hospitalized patients and during a follow-up period. We calculated the hospitalization rate as the number of total hospitalizations divided by the disease duration, and defined "frequent hospitalization" as hospitalization more than once per year. Results Of the 196 patients, 117 (59.6%) were admitted to hospital a total of 257 times during the 8-year follow-up period. Moreover, 22 (11.2%) patients were hospitalized frequently. The most common reasons for hospitalization included disease flares, infection, and pregnancy-related morbidity. In the univariate regression analysis, malar rash, arthritis, pericarditis, renal involvement, fever, systemic lupus erythematosus disease activity index > 12, hemoglobin level < 10 mg/dl, albumin level < 3.5 mg/dl, and anti-Sjögren's syndrome A positivity were associated with frequent hospitalization. Finally, multivariate analysis showed that arthritis, pericarditis, and anti-Sjögren's syndrome A antibody positivity at the time of diagnosis were risk factors for frequent hospitalization. Conclusions Our results showed that frequent hospitalization occurred in 11.2% of hospitalized patients and arthritis, pericarditis, and anti-Sjögren's syndrome A antibody positivity at the time of diagnosis were risk factors for frequent hospitalization.