Site-specific mortality in native joint septic arthritis: a national population study

Abstract

Abstract Objective This national cohort study investigated the incidence, site-specific mortality and prognostic factors of native septic arthritis (SA). Methods Tapping Taiwan’s National Health Insurance Research Database, we identified inpatients with newly diagnosed SA between 1998 and 2012. They were categorized by site of infection and followed to calculate 30-day, 90-day and 1-year mortality. Predictors of mortality were calculated using Cox models. Results A total of 31 491 patients were identified as having SA, the most common site of infection being the knee (50.1%), followed by the hip (14.4%), other sites (26.8%), the shoulder (5.5%) and multiple sites (1.2%). Knee joint involvement was the most common site for all subgroups. Incidence increased from 9.8/105 in 1998 to 13.3/105 in 2012. The 30-day, 90-day and 1-year mortality rates were 4.3, 8.6 and 16.4% respectively. Predictors for mortality were hip infection, shoulder infection, multiple-site infection, being male, age ≥65 years old and comorbidities. We derived a mortality scoring model over age/SA site/comorbidity, and age ≥65 years old had the greatest risk contribution to mortality. No matter whether 1-month, 3-month or 1-year mortality was being considered, patients with the higher risk scores had the higher mortality rates (P < 0.0001). Conclusion SA is an emerging infectious disease with a rising incidence, long duration of hospital stay and high mortality rate. The most common affected joint was knee for all subgroups. Patients aged ≥65 years old had a high SA incidence and the greatest risk contribution.