Opportunistic infection risk highest for patients with polymyositis, dermatomyositis
Among systemic rheumatic diseases, the risk for opportunistic infection is highest among patients with polymyositis or dermatomyositis, followed by systemic lupus erythematosus, systemic sclerosis, rheumatoid arthritis and primary Sjögren’s syndrome, according to data published in Arthritis Research & Therapy.
“In addition to common infections, opportunistic infection (OI) has emerged as an important complication in developed countries,” Chung-Yuan Hsu, MD, of Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine in Taiwan, and colleagues wrote. “Interestingly, the risks of herpes zoster and Pneumocystis jiroveci pneumonia are elevated among SLE patients, while [dermatomyositis] was recently shown to be associated with elevated rates of herpes zoster and tuberculosis.”
“However, most previous studies regarding the relationship between rheumatic diseases and OI were focused on SLE and were limited by their small-scale or single-center designs,” they added. “Furthermore, there is scarce research regarding the incidence rates (IRs) of OI in other major connective tissue diseases, such as systemic sclerosis (SSc) and primary Sjögren’s syndrome (pSS). Moreover, among patients with [polymyositis/dermatomyositis (PM/DM)] or SLE, there are no large-scale studies regarding the incidences of other OIs (eg, aspergillosis, cryptococcosis, non-tuberculous mycobacteria, and cytomegalovirus infection).”
To estimate and analyze the burdens of opportunistic infections and herpes zoster among patients with various systemic rheumatologic diseases, Hsu and colleagues conducted a 13-year retrospective cohort study of information in Taiwan’s National Health Insurance Research Database. According to the researchers, the database includes relevant diagnostic and procedural codes, for more than 23 million people, or approximately 99% of Taiwan’s population.
Focusing their analysis on 2000 to 2013, they used the national health data to compare the incidence rates of several opportunistic infections among patients with five rheumatic diseases. The included infections were candidiasis, aspergillosis, Cryptococcus, Pneumocystis jiroveci, cytomegalovirus infection, salmonellosis, tuberculosis, non-tuberculous Mycobacterium infection, herpes zoster, toxoplasmosis, coccidioidomycosis and histoplasmosis. The researchers identified and included 76,966 patients in their analysis. These included 2,270 patients with polymyositis or dermatomyositis, 15,961 with SLE, 2,071 with SSc, 38,355 with RA and 18,309 with primary Sjögren’s syndrome.
Hsu and colleagues used Poisson regression to stratify the analysis according to follow-up duration, as well as Cox models to compare risks for infection.
According to the researchers, the incidence rate for opportunistic infections was highest among patients with polymyositis or dermatomyositis, with 61.3 per 1,000 person-years, (95% CI, 56.6-66.2). This was followed by patients with SLE, with 43.1 per 1,000 person-years (95% CI, 41.7-44.5); those with SSc, at 31.6 per 1,000 person-years (95% CI, 28.3-35.1); individuals with RA, at 25 per 1,000 person-years (95% CI, 24.4-25.7); and those with primary Sjögren’s syndrome, with 24.1 per 1,000 person-years (95% CI, 23.1-25.2).
In addition, following multivariable Cox analysis, the researchers found that, relative to lupus, polymyositis/dermatomyositis was associated with a significantly higher risk for opportunistic infections (HR = 1.18; 95% CI, 1.08-1.29). Hsu and colleagues also found that, for all five included diseases, the risk for opportunistic infections was highest during the first year following diagnosis.
“This nationally representative cohort study revealed that patients with PM/DM had the highest risk of OI, followed by SLE, SSc, RA, and pSS, in order of decreasing risk,” Hsu and colleagues wrote. “Furthermore, the highest risk of OI was observed during the first year after the diagnosis of systemic rheumatic disease, especially in cases of PM/DM. These findings highlight the importance of monitoring for OI development during the treatment of these autoimmune rheumatic diseases, especially for patients with PM/DM.” – by Jason Laday
Disclosure: The researchers report no relevant financial disclosures.