Epidemiological features and outcomes of patients with psoas abscess: A retrospective cohort study

Background: Psoas abscess (PA) is an uncommon disease. Although PA is associated with significant morbidity and mortality, its epidemiology and clinical characteristics remain unknown. This study aimed to evaluate the epidemiological and clinical features and outcomes of patients with PA in a prefectural-wide study. Materials and methods: This was a multicenter retrospective cohort study conducted between 2010 and 2012 in the Miyagi prefecture with a population of 2,344,062 in 2011. Adult patients with PA were enrolled from 71 secondary and tertiary care hospitals. Results: There were 57 patients with adult PA in the Miyagi prefecture. The median age of the patients was 72 years, and 67% patients were male. Fever and flank pain were the primary symptoms in 82% and 74% of patients, respectively. Ten patients (18%) had septic shock, and the hospital mortality rate was 12%. Secondary PA was present in 72% of cases, and the most common origin was pyogenic spondylitis. Of the patients with secondary PA, 44% had an epidural abscess. The most common pathogens were Staphylococcus aureus, and 11% (6 cases) of the cases were caused by methicillin-resistant S. aureus. Conclusion: In the Miyagi prefecture of Japan, the estimated prevalence of PA was 1.21/100,000 population years and hospital mortality was 12%. Secondary PA accounted for more than 70% of the cases, and S. aureus was the most common causative pathogen.