AB1358 AN OLD METHOD FOR CURRENT CHALLENGES: SKIN TEST CONVERSION OF PURIFIED PROTEIN DERIVATIVE (PPD) IN RHEUMATOLOGICAL PATIENTS TREATED WITH ANTI-TNF-α

Abstract

BackgroundAnti-TNF-α are a cornerstone for the treatment of multiple rheumatic diseases. They are associated with an increased risk of developing tuberculosis (TB), which is endemic in several countries and an important burden across the globe. Purified protein derivative (PPD) is one of the tests used to demonstrate a latent TB infection (LTBI). Screening is recommended for TB prior to the onset of anti-TNF-α and monitoring evaluating possible conversion of PPD during treatment, defined as the change from a negative (<5 mm) to positive result (≥5 mm). Identification and treatment of LTBI can reduce the risk of disease development by up to 90%. Currently the results of PPD conversion and its interpretation during anti-TNF-α treatment are variable and that is why we set out to know the frequency of conversion of PPD in this group of patients in our environment.ObjectivesTo identify PPD conversion in patients with rheumatological diseases undergoing anti-TNF-α treatment.MethodsA descriptive, analytical, observational, retrospective study was conducted from January 1, 2018 to January 1, 2022. Inclusion criteria: Patients >18 years old, diagnosed with rheumatological diseases and treated with anti-TNF-α for more than 3 consecutive months, with a negative PPD (<5 mm diameter) previous starting anti-TNF-α and a normal chest X-ray.Results62 patients (age 45.8 ± 12.5 years), with rheumatological diseases (41 rheumatoid arthritis, 7 juvenile idiopathic arthritis, 5 ankylosing spondylitis, 4 psoriatic arthritis, 4 uveitis and 1 interstitial keratitis) under anti-TNF-α therapy (35 adalimumab, 18 certolizumab, 9 etanercept) were included. Concomitant use of immunomodulators (52 methotrexate, 23 leflunomide, 10 hidroxicloroquine, 3 sulfasalazine, 2 azathioprine and 1 mycophenolate mofetil) and glucocorticoids (33/62) was observed. The conversion of PPD took place in 4 patients (6.5%) (Table 1).Table 1.“Patient’s characteristics”SexAgeRDanti-TNF-αTime doing anti-TNF-αDMARDGCSPPDChest X-rayTB prophylaxis1Male66PsAadalimumab6 yearsmethotrexateNo5 mmNormalIsoniazid2Female56RAadalimumab10 yearsmethotrexateNo5 mmNormalIsoniazid3Female62RAadalimumab5 yearsmethotrexateYes10 mmNormalIsoniazid4Male45AScertolizumab1 yearNoNo20 mmNormalIsoniazidAS, ankylosing spondylitis; DMARD, disease-modifying antirheumatic drugs; GCS, glucocorticosteroids; PPD, purified protein derivative; PsA, psoriatic arthritis; RA, rheumatoid arthritis; RD, rheumatological disease; TB, tuberculosis.ConclusionConsidering the prevalence of TB in our country, this research showed a lower PPD conversion percentage compared to previous reports. Anti-TNF-α have radically changed the evolution of rheumatological diseases, considerably improving the patient’s quality of life. With the increase in the accessibility of anti-TNF-α worldwide, new challenges have arisen regarding infectious diseases such as TB, which is endemic in some countries. PPD is a well known, cheap, sensitive and widely available method, suitable for LTBI diagnosis. Although sensitivity could be increased using, in addition, other LTBI detection methods such as IGRAs (interferon gamma release assays), they are usually unavailable in developing countries (1-3).