Abstract
OBJECTIVE: As immune-modulating therapy has become the standard of care for idiopathic inflammatory joint diseases (IJD), we investigated whether this has changed the rates for hospitalization with opportunistic infections (OI). METHODS: Administrative longitudinal state-wide health data identified patients hospitalized at least twice with diagnostic codes for rheumatoid arthritis (RA, n = 7730), psoriatic arthritis (PsA, n = 529) or axial spondylarthritis (AS, n = 1126) in Western Australia in the period 1985-2015. Overall incidence rates/1000 person-years (IR with 95% CI) for microbiologically confirmed OI (mycobacterial, fungal, and viral infections) during 180,963 person-years were analyzed across 10-year periods with IR trend rates analyzed by least square regression (R(2)) for all IJD categories. RESULTS: A total of 2584 OI occurred with higher IR rates observed in RA (15.34, CI 14.71-15.99) than PsA (8.73, CI 7.14-10.56) and AS (10.88, CI 9.63-12.24) patients (p < 0.001). IR rates were highest for Candidiasis across all three IJD categories (IR 10.0 vs. 6.32 vs. 6.88, respectively), while Varicella-zoster (VZV) was most frequent non-candida OI (IR 2.83.0 vs. 1.50 vs. 1.49, respectively) followed by mycobacterial (IR 1.14 vs. 0.08 vs. 0.24, respectively) and other mycotic infections (IR 0.60 vs. 0.58 vs. 0.86, respectively). Over time, the IR for tuberculosis and pneumocystosis decreased and remained stable for VZV infections in RA patients, but IR for all other OI increased across all disease categories. OI admission associated with 6.5% (CI 5.6-7.5) in-hospital mortality. CONCLUSIONS: Despite decreasing admission rates for tuberculosis and pneumocystosis in RA patients, an overall increase in mycotic and viral infection rates over time was seen across all three IJD. Together with a significant case fatality rate, this indicates continued efforts are needed to improve OI prevention in the management of IJD patients.