Acta Dermato-Venereologica 98-10CompleteContent | Page 16
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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