Objective: To assess incidence, time-trends, and outcomes of serious infections in people with polymyalgia rheumatica (PMR) or giant cell arteritis (GCA).

Methods: We examined the 1998-2016 US National Inpatient Sample for serious infections in PMR or GCA, namely, opportunistic infections (OI), skin and soft tissue infections (SSTI), urinary tract infection (UTI), pneumonia, and sepsis/bacteremia. Multivariable-adjusted logistic regressions assessed association of the type of infection, demographics, comorbidity, and hospital characteristics with healthcare utilization and mortality.

Results: Hospitalized with serious infections, those with PMR or GCA were 2 decades older than people without PMR or GCA, and more likely to be female or white or have higher Deyo-Charlson index score or higher income. Sepsis rates in the general population, PMR, and GCA cohorts were 10.2%, 17.7%, and 18.9% in 2015-2016, respectively. Incidence rates of serious infections/100,000 NIS claims in PMR and GCA in 2015-2016 were as follows (rounded off): OI, < 1 and < 1; SSTI, 4 and 1; UTI, 4 and 1; pneumonia, 9 and 2; and sepsis, 20 and 4, respectively. Sepsis surpassed pneumonia as the most common serious infection in 2011-2012. In multivariable-adjusted analyses in the PMR cohort, sepsis, female sex, Deyo-Charlson comorbidity score ≥ 2, Medicare or Medicaid insurance, urban hospital location, and large hospital bed size were associated with significantly higher healthcare utilization and/or in-hospital mortality. Similar associations were noted in the GCA cohort.

Conclusions: Incidence of serious infections, especially sepsis, increased in both PMR and GCA cohorts over time. Interventions to improve serious infection outcomes in PMR/GCA are needed. Key Points • PMR/GCA patients with hospitalized serious infections were 2 decades older than the general population. • Sepsis surpassed pneumonia as the commonest hospitalized serious infection in PMR/GCA in 2011-2012. • Sepsis, female sex, comorbidity, Medicare/Medicaid insurance, and urban location were associated with higher healthcare utilization and in-hospital mortality.