Acta Dermato-Venereologica 98-10CompleteContent | Page 16

979 SHORT COMMUNICATION Tuberculosis Screening in Patients with Psoriasis Receiving Biologic Therapy: A Retrospective Cohort Study Igor SNAST 1 , Einav BERCOVICI 1 , Tomer AVNI 2 , Dorit SHITENBERG 3 , Emmilia HODAK 1,4 and Lev PAVLOVSKY 1 * 1 Department of Dermatology, 2 Unit of Infectious Diseases, and 3 Pulmonary Institute, Rabin Medical Center – Beilinson Hospital, Petach Tikva 4941492, and 4 Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel. *E-mail: [email protected] Accepted Jul 27, 2018; Epub ahead of print Aug 7, 2018 Biologic therapies pose a risk of opportunistic infection, especially of reactivating latent tuberculosis infection (LTBI). Therefore, screening for LTBI is mandatory prior to commencing biologic treatment (1). Traditionally, the tuberculin skin test (TST) is used for LTBI screening, but its specificity is low, leading to unnecessary antibiotic treatment (2). Since 2001, researchers have developed ex vivo assays measuring interferon-gamma (IFN-γ) produc- tion by T cells exposed to specific mycobacterial antigens: T-SPOT.TB, QuantiFERON TB Gold (QFT) and QFT in tube. As IFN-γ-releasing assays (IGRAs) have high spe- cificity, they are recommended as the screening method of choice by the British Association of Dermatologists (3). Nonetheless, because of their high cost, IGRAs are frequently used only as confirmatory tests in patients with an initial positive TST result (4). However, the agreement between these tests is poor, and the question of the need for chemoprophylaxis in patients with discordant results remains unresolved (4, 5). This real-life study aimed to determine the prevalence of TST positivity in patients with psoriasis prior to the initiation of biologic therapy, and the safety of biologics without chemoprophylaxis in patients with discordant results. PATIENTS, METHODS AND RESULTS This study was approved by the ethics committee of Rabin Medical Center. A retrospective cohort study design was used. The data- base of a tertiary dermatology department was searched for all consecutive patients treated with biologics for moderate-severe psoriasis since 2005. Prior to treatment, patients were screened for LTBI with chest X-ray (CXR) and TST, with or without the QFT. Patients paid for the QFT out-of-pocket until 2016, when the health insurance funds categorized it as reimbursable if TST was positive. TST was considered positive if the induration measured ≥ 5 mm at 48–72 h. QFT was considered positive when the IFN-γ response was ≥  0.35 IU/ml (manufacturer’s instructions). Patients were evaluated every 2–3 months until follow-up ended and for suc- cessive TST screening annually. Chemoprophylaxis with isoniazid (300 mg daily; 9 months) or rifampicin (600 mg daily; 4 months) was administered under the following conditions: (i) TST ≥ 5 mm and unavailable QFT; (ii) positive QFT; or (iii) abnormal CXR. The www.bcgatlas.gov website was used to assign BCG status in each patient’s country of origin (6). Countries with an annual incidence > 40 per 100,000 population were defined as endemic. Of the 280 patients, 264 (94%) were screened with the TST. In 95 patients (36%), TST was positive either before or during tre- atment (Fig. 1). Table SI 1 summarizes the clinical characteristics of the TST-positive patients. During a mean follow-up of 51  ±  40 months, none of the patients acquired active tuberculosis. The TST-positive patients included 53 men and 42 women of mean age 52  ±  14 years. Forty-eight patients (51%) were born when BCG vaccination was indicated at birth, and 35 (37%) were immigrants from endemic countries. None had a history of tuberculosis. A similar rate (50%) of BCG vaccination was found among the 169 TST-negative patients. Screening data. Mean TST induration size was 12  ±  5 mm. TST was positive at baseline in 78/264 patients (30%) and negative in 186. Fifty-two patients with a negative TST result (28%) underwent successive screening during treatment; 17 (33%) experienced TST conversion. Of the total 95 TST-positive patients, 43 (45%) underwent confirmatory screening with the QFT (including 10 who underwent conversion) and 39 (90%) had a discordant result (TST+/QFT–). Four of them (10%) received chemoprophylaxis for the following reasons: TST induration of 18 and 30 mm (n = 2); equivocal CXR findings (n = 1); unclear indication (n = 1). The other 35 (81% of QFT-tested group) were safely treated with biologics without chemoprophylaxis (Table SII 1 ). For the re- maining 52 TST-positive patients, QFT results were unavailable. https://www.medicaljournals.se/acta/content/abstract/10.2340/00015555-3007 1 Fig. 1. Flow chart showing the distribution of tuberculin skin test (TST) results, QuantiFERON TB Gold (QFT) results, and chemoprophylaxis during the study period. This is an open access article under the CC BY-NC license. www.medicaljournals.se/acta Journal Compilation © 2018 Acta Dermato-Venereologica. doi: 10.2340/00015555-3007 Acta Derm Venereol 2018; 98: 979–980