Opportunistic infections in patients with idiopathic inflammatory myopathies.

AIM: To describe the prevalence, clinical characteristics and risk factors of opportunistic infection (OI) in a cohort of patients with inflammatory myopathies, and compare mortality rates between those with and without OIs.

METHODS: In total, 204 patients from our myositis cohort were reviewed to identify patients who had experienced an OI during the period 1986-2014. The patients' clinical characteristics, treatments received, and outcomes were systematically recorded. Disease activity at the OI diagnosis and the cumulative doses of immunosuppressive drugs were analyzed, as well as the specific pathogens involved and affected organs.

RESULTS: The prevalence of OI in the total cohort was 6.4%: viruses, 44.4% (varicella-zoster virus, cytomegalovirus); bacteria, 22.2% (Salmonella sp., Mycobacterium tuberculosis, M. chelonae); fungi, 16.7% (Candida albicans, Pneumocystis jirovecii); and parasites, 16.7% (Toxoplasmosis gondii, Leishmania spp.). Lung and skin/soft tissues were the organs most commonly affected (27.8%). Overall, 55.6% of OIs developed during the first year after the myositis diagnosis and OI was significantly associated with administration of high-dose glucocorticoids (P = 0.0148). Fever at onset of myositis (P = 0.0317), biological therapy (P < 0.001) and sequential administration of four or more immunosuppressive agents during myositis evolution (P = 0.0032) were significantly associated with OI. All-cause mortality in the OI group was 3.69 deaths per 100 patients/year versus 3.40 in the remainder of the cohort (P = 0.996).

CONCLUSIONS: The prevalence of OI was 6.4% in our myositis cohort, higher than the rest of the inpatients of our hospital (1.7%; P < 0.01). High-dose glucocorticoids at disease onset and severe immunosuppression are the main factors implicated.