Elevated TB risk in individuals with SLE
Individuals with systemic lupus erythematosus (SLE) have an elevated risk of tuberculosis (TB), according to a local study.
“In our study, we found that SLE patients had a risk of having TB that was almost five times that of patients without SLE,” said the researchers. “Patients with SLE should be considered a high-risk group for TB,” they said.
Using the discharge database of Singapore General Hospital (SGH), researchers identified 841 patients with SLE (mean age 53.9 years, 86.2 percent female) and 1,843 patients with TB from a cohort of 301,568 individuals who were hospitalized at SGH between 2004 and 2011.
The rate of TB was significantly higher among individuals with SLE compared with those without SLE (2.0 percent vs 0.6 percent; p<0.001), specifically with regards to pulmonary TB (1.7 percent vs 0.5 percent; p<0.001). [Rheumatol Int 2017;doi:10.1007/s00296-017-3696-3]
After adjusting for age, gender, ethnicity, admission class, nutritional deficiency, organ transplantation, and Charlson comorbidity index grade, SLE was found to be an independent predictor of TB (odds ratio, 4.6, 95 percent confidence interval, 2.8–7.5; p<0.001).
Among the potential reasons cited by the researchers for the elevated risk were “immunologic and genetic alterations” in individuals with SLE that increase their likelihood of developing infections, as well as the use of immunosuppressive drugs.
“Molecular mimicry has been suggested as a possible mechanism ... another plausible mechanism involves heat-shock proteins, which act like the dominant antigens of nonviral microorganisms and mycobacteria,” said the researchers. “Vitamin D deficiency as a result of immune-mediated disease increasing TB risk has also been hypothesized.”
The researchers acknowledged that a lack of data on other potential influencing factors such as smoking habits, body mass index, and disease severity presented a limitation. Furthermore, the results may vary in other hospitals as the data used in this study was obtained from just one tertiary institution, they said, and recommended active screening for latent patients as well as treatment for patients who test positive for TB.