Rehospitalization to evaluate outcomes during clinical courses in patients with elderly-onset idiopathic inflammatory...

The features of rehospitalization, associated with the long-term clinical outcome, remain uncertain in idiopathic inflammatory myositis (IIM). We evaluated the frequency and causes of rehospitalization in patients with elderly (≥ 65 years)-onset IIM, EOM compared to those with young (< 65 years)-onset IIM (YOM).

Electronic medical records of patients with IIM were reviewed over 6 years. Rehospitalization was defined as first admission during outpatient care following successful induction and maintenance of IIM treatment. Opportunities, causes, and relevant factors for hospitalization were obtained for patients with EOM and those with YOM.

There were 108 patients identified: 34 with EOM (median age, 71 years; 22 women) and 74 with YOM (median age, 49 years; 52 women). Rehospitalization was significantly higher in patients with EOM (n = 25, 73.5%) compared to those with YOM (n = 36, 48.6%) during a 2-year observation period (p < 0.05). In the rehospitalized patients with EOM, there was a significantly lower deterioration in disease activity (n = 8; p < 0.05) but higher incidence of infections present (n = 5; p < 0.05) compared to those with YOM. The Cox proportional hazards model indicated a significant association between increased age and rehospitalization (hazard ratio, 1.024; 95% confidence interval, 1006‒1.042; p < 0.05).

Patients with EOM were more likely to experience rehospitalization, and infections were identified more significantly compared to those with YOM. These findings may be useful for managing the long-term clinical outcome in IIM. Key Points • Patients with elderly-onset idiopathic inflammatory myositis (IIM) are more likely to be rehospitalized than those with young-onset IIM. • Among patients who experienced rehospitalization, those with elderly-onset IIM had a significantly higher rate of remission than those with young-onset IIM. • As a cause of rehospitalization, infections were significantly more common in patients with elderly-onset IIM than in those with young-onset IIM.