Trends in Hospitalizations for Serious Infections in Patients With Rheumatoid Arthritis in the US Between 1993 and 2013

ObjectiveThe epidemiology of hospitalizations with infections among patients with rheumatoid arthritis (RA) is unknown, despite an increase in RA treatments that confer a risk of infection. MethodsWe examined National Inpatient Sample data from 1993-2013. We identified hospitalizations among adults with RA, defined by International Classification of Diseases, Ninth Revision, Clinical Modification codes (714.xx) in any secondary diagnosis field. We evaluated 5 infections as the primary diagnosis: pneumonia, sepsis, urinary tract infection (UTI), skin and soft tissue infections (SSTIs), and opportunistic infections (OIs). The primary outcome was the proportion of hospitalizations for each infection among all hospitalizations with a secondary diagnosis of RA. ResultsThere were 792,921 hospitalizations for infection with a secondary diagnosis of RA, with the rates increasing from 90 to 206 per 100,000 persons from 1993-2013. The proportion of hospitalizations decreased for pneumonia (from 5.4% to 4.6%), UTI (from 0.4% to 0.38%), and OIs (from 0.44% to 0.26%). The proportion of hospitalizations for SSTIs increased slightly (from 2.3% to 2.5%), while hospitalizations for sepsis more than tripled (from 1.9% to 6.4%). ConclusionBetween 1993 and 2013, the proportion of hospitalizations for infections among RA patients appeared to decline for pneumonia and OIs, with a slight decrease in UTI, a slight increase in SSTIs, and a substantial increase in hospitalizations with sepsis. Our results are consistent with previous reports that the sensitivity of sepsis coding has increased over time.