765. Pyomyositis in the United States: Trends and Associations From the Healthcare Utilization Project Nationwide Inpatient Sample Database

BACKGROUND: Pyomyositis is a spontaneous infection of skeletal muscle that can lead to abscess formation and sepsis. The purpose of our study was to better describe the characteristics, risk factors, and trends of primary pyomyositis in the United States. METHODS: This study is a retrospective review of data from the Healthcare Utilization Project Nationwide Inpatient Sample Database from 2002 to 2014. We systematically searched ICD-9 codes and included diagnoses of infective myositis and/or tropical pyomyositis and excluded progressive myositis ossificans and/or traumatic myositis ossificans. We compiled lists of codes for co-occurring infections, candidate risk factors, and microbiological data. Each group of related ICD-9 codes was combined into a single composite indicator. SAS studio was utilized for analysis. RESULTS: The database included a total of 100,790,900 discharges accounting for 482,872,274 weighted discharges with 13,011 pyomyositis cases accounting for 62,657 weighted cases. The patients with pyomyositis were significantly more likely to be younger, male, and have a longer duration of hospitalization. The proportion of discharges with pyomyositis has steadily risen more than 3-fold from 0.0054% to 0.0209%. Of the cases of pyomyositis, a minority had co-occurring deep tissue infections: 16.9% had osteomyelitis and 8.8% had septic arthritis. We found significantly higher rates of co-occurrence with HIV, diabetes mellitus, organ transplant, alcohol abuse, and chronic kidney disease compared with the general hospitalized population, suggesting these as relevant risk factors. When microorganisms were diagnosed, Staphylococus aureus was most common, followed by Streptococcus spp. CONCLUSION: Our study identified a rapid increase in pyomyositis cases in the United States over our 12-year study period. Our results substantiate risk factors for pyomyositis related to immunosuppression and suggest that diabetes mellitus may be an important risk factor in the United States. Identifying causative organisms is helpful for empiric treatment. It is important that clinicians be aware of this emerging diagnosis relevant in both temperate and tropical areas of the globe. [Image: see text] [Image: see text] [Image: see text] [Image: see text] DISCLOSURES: All authors: No reported disclosures.