Some of the 2 million patients in the United States who have rheumatoid arthritis (RA), an autoimmune inflammatory disease, are treated with antitumor necrosis factor (anti-TNF) therapy, which suppresses the immune system. A new study found that rates of tuberculosis (TB) and nontuberculous mycobacterial (NTM) disease among anti-TNF therapy users to be fivefold to tenfold higher than disease rates seen in patients with RA not taking these drugs and the general population.
The researchers advise clinicians to continue to screen for TB prior to use of anti-TNF therapy and to remain vigilant for the presence or development of NTM disease in patients who use these therapies. They identified 8,418 patients belonging to the Kaiser Permanente Northern California (KPNC) health maintenance organization, who received anti-TNF therapy between the beginning of 2000 and the end of 2008. They found that 61 percent of these patients had diagnosis codes for RA in their medical records; 64 percent were women, and 61 percent were non-Hispanic whites. Within this group, the researchers identified 16 patients who developed TB at a median of 670 days after starting anti-TNF therapy, and 18 patients who developed NTM infections at a median of 1,027 days after starting this therapy.
The incidence of TB per 100,000 person-years was 56 among patients with RA treated with anti-TNF therapy compared with 2.8 per 100,000 person-years among the general population of KPNC patients. For NTM diseases, the incidence per 100,000 patient-years was 105 (RA anti-TNF users) versus 4.1 (general KPNC population). Patients who were anti-TNF users who were at risk for developing TB were 80 percent less likely to be white, 3 times more likely to have diabetes, and 4.8 times more likely to have chronic kidney disease. Those at risk for developing NTM diseases were 11 times more likely to be white, 5.3 times more likely to have gastroesophageal reflux disease, and 6.5 times more likely to have chronic lung disease.
The researchers used data from the KPNC automated pharmacy records to identify patients who received anti-TNF therapy during 2000–2008. The study was funded in part by AHRQ (HS17552).
More details are in "Mycobacterial diseases and antitumor necrosis factor therapy in USA," by K.L. Winthrop, M.D., M.P.H., R. Baxter, M.D., L. Liu, M.S., and others in the January 2013 Annals of Rheumatic Disease 72(1), pp. 37–42.