PPD level changes for patients with inflammatory rheumatic diseases treated with anti TNF-α drugs

Ankylosing spondylitis (AS) and rheumatoid arthritis (RA) are inflammatory disease that cause severe morbidity, mortality and adversely affect the quality of life of these patients. Nowadays, blocking TNF-α has opened a new era in the treatment of these inflammatory diseases and implementation in early period enables us to mention about providing very low disease activity or remission probabilities. But, with the introduction of these drugs, tuberculosis has begun to be reported more frequently in patients under treatment and studies showed that tuberculosis exposure was significantly higher in treatment group compared to the control group. Before initiation of anti-TNF-α treatment, identification of latent tuberculosis infection and the need of prophylaxis must be determined. Nowadays PPD is the most inexpensive and easy to apply modality of test in identification of latent tuberculosis infection. In line of recommendations, Isoniazid (INH) prophylaxis must be given before usage of anti-TNF-α agents for patients who are considered to have latent tuberculosis. It is indicated that 50-80% of active tuberculosis cases can be reduced by diagnosis and treatment of latent tuberculosis infection. Although numerous studies has shown that these drugs increased the risk of tuberculosis, their impact on PPD levels are not still well known. In literature, only a small number of studies that investigate the effects of anti-TNF drug usage on PPD response are present. Therefore, in our study, for anti-TNF-α treated patients with inflammatory rheumatic diseases (rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, juvenile chronic arthritis), we evaluated routinely performed PPD levels before treatment and changes in the level of PPD repeated during checks of anti-TNF-α treatment. In these patients, according to the results of initial and control PPD levels, we compared the rates of INH prophylaxis. For patients which do not receive INH prophylaxis, it's aimed to re-evaluate the necessity of preventive treatment according to the results of control PPD. In this study, patients who were followed between 2005-2013 at Akdeniz University Medical Faculty Hospital, Physical Medicine and Rehabilitation-in Rheumatology Clinics and Diagnosed as 27 RA, 77 AS, 6 PsA, 7 JKA receiving anti-TNF-α treatment, a total of 117 patients were included. PPD levels routinely measured before treatment of patients who have been using anti-TNF drugs longer than 1 year, PPD changes repeated in controls, onset INH prophylaxis rates according to initial and control PPD results were conducted in this study. In our study, of 117 patients using anti-TNF drugs, mean of starting PPD levels was 5,87±5,45 mm whereas mean of control PPD was 8.29±6.40 mm. A statistically significant increase has been found in control PPD mean after anti-TNF drug treatment compared to the mean of starting PPD levels, (p<0,001). In our study, INH prophylaxis was given for 99 (84.6%) of the 117 patients. INH prophylaxis was given according to the starting PPD levels for 63 (53%) to 99 patients given INH prophylaxis and according to control PPD results for 36 (30%) patients of those remaining 54 patients. No significant relationship is obtained between varieties of disease, anti-TNF drug type and INH prophylaxis initiation according to the results of control PPD levels. In our study, there was no significant relationship between the given INH prophylaxis initiation and type of anti-TNF drugs, sex, diagnosis of disease. As a result, for patients with rheumatoid disorder treated anti-TNF drugs, activation of tuberculosis is a major problem. The level of PPD may vary with the regulation of the immune response in the treatment process. Therefore, repeating PPD test at certain intervals during later stages of treatment and further evaluation of these patients for prophylaxis may be suggested to identify patients who should receive prophylaxis. Key words: PPD level changes, Anti TNF therapy, latent tuberculosis infection, rheumatoid arthritis, ankylosing spondylitis.