Incidence of tuberculosis in patients receiving anti-TNF therapy for rheumatic diseases: a systematic review

Tuberculin skin test repetition after TNF-α inhibitors in patients with chronic inflammatory arthritis: a long-term retrospective cohort in endemic area

OBJECTIVES

To evaluate the tuberculin skin test (TST) conversion in chronic inflammatory arthropathies (CIA) patients on TNFα inhibitors (TNFi) and without previous latent tuberculosis infection (LTBI) treatment.

METHODS

Patients with rheumatoid arthritis (RA), ankylosing spondylitis (AS) and psoriatic arthritis (PsA) with negative LTBI were retrospectively evaluated for TST conversion and active tuberculosis (TB) after six months of exposition to TNFi. Two groups were compared: patients who repeated TST (TST-repetition) during the follow-up and patients who did not (non-TST-repetition).

RESULTS

A total of 355 CIA patients on TNFi were screened and 138 (38.9%) did not fulfill the inclusion criteria. Of the remaining 217 CIA patients, 81 (37.3%) repeated TST during TNFi treatment. TST conversion rate was observed in 18 (22.2%) patients without significant differences among CIA (p = 0.578). The number of TB cases was low (n = 10; 4.6%) and was similar in TST-repetition and non-TST-repetition groups [2 (2.5%) vs. 8 (5.9%), p = 0.328]. Of note, 30% of active TB occurred early (6-12 months of TNFi exposure) and the median (full range) time to incident TB was 1.3 (0.6-10.6) years, whereas the median (full range) time to TST repetition was later [3.3 (0.5-13.4) years]. The incidence of active TB was lower among RA patients than AS patients [342 (95% CI 41 - 1446) vs. 1.454 (95% CI 594-2993)/100,000 patient-years, p = 0.049].

CONCLUSION

These results indicate that TST repetition is associated with a high conversion rate, suggesting the need for recommended treatment. The delayed repetition of TST and low number of active TB cases hampered the evaluation of this strategy effectiveness to prevent active infection. Larger studies with systematic repetition patterns are necessary. In addition, the study highlights the need for a greater surveillance for TB in AS patients.

Disseminated tuberculosis after anti-TNF alpha treatment: Do not blindly trust the IGRA test

INTRODUCTION

Interferon gamma release assay (IGRA) is used to detect latent tuberculosis prior to biological treatments in the context of suspected inflammatory rheumatism.

METHODS

We report the case of a 50-year-old woman with negative IGRA test before adalimumab introduction for presumed axial spondyloarthritis.

RESULTS

The worsening of symptoms under treatment led to further investigations and the diagnostic of disseminated tuberculosis (TB) was later established with miliary and multiple bone locations such as spondylitis and sacroilitis. The patient's history revealed past exposure to tuberculosis. This observation illustrates the limitations of IGRA in such situation due to its variable performance for active TB diagnosis.

CONCLUSION

Misdiagnosis is frequent in bone tuberculosis due to non-specific signs. We draw the attention to the importance of a global risk assessment prior to the introduction of biological treatment for suspected chronic inflammatory rheumatism and recall the risk factors for false-negative IGRA. An extended treatment course may be necessary after exposure to anti-TNF-alpha.

Prevalence of LTBI in patients with autoimmune diseases and accuracy of IGRA in predicting TB relapse

OBJECTIVES

The current study evaluated latent tuberculosis infection (LTBI) positivity in a cohort of Indian subjects and the accuracy of IFN-gamma release assay (IGRA) in predicting tuberculosis (TB) reactivation.

METHODS

This cross-sectional, retrospective chart-based study considered patients diagnosed with autoimmune rheumatic diseases (AIRDs), especially those who received treatment with biologics or targeted synthetic (ts)DMARDs. The patients had undergone LTBI screening and IGRA test. The study excluded patients with inadequate information and those who had undergone test exclusively for diagnostic purpose. Statistical analyses were carried out for descriptive, demographic and clinical variables. Accuracy and error rate in predicting the absence of TB reactivation were calculated for IGRA test.

RESULTS

The study selected 943 patients who had undergone IGRA pre-screening prior to the initiation of biologics or tsDMARDs with a mean age of 42.93 ± 14.01 years and male-to-female ratio of 1:2.08. RA was the most common primary diagnosis (43.16%). The proportion of subjects who received single, double and triple or more DMARDs or immune suppressants were 54.35%, 33.33% and 7.69%, respectively. Among the selected subjects, 125 patients were LTBI positive and 816 were negative. All patients, except one who tested positive at baseline, received antitubercular prophylaxis. Accuracy of IGRA in predicting the absence of TB reactivation was 99.6%, with an error rate of 0.46.

CONCLUSION

LTBI screening is beneficial in AIRDs patients prior to the prescription of biologics or tsDMARDs. IGRA is ideal for identifying patients with increased likelihood of developing TB upon receiving biologics or tsDMARDs with reasonable accuracy.

Laryngeal tuberculosis in patients treated with adalimumab: a casual or causal connection?

This article presents two consecutive cases of laryngeal tuberculosis in patients treated with a specific anti-tumour necrosis factor-alpha (adalimumab), with a focus on their diagnostic process and therapeutic management. Both patients presented with aspecific chronic laryngeal symptoms that had been worsening for a few months in one case and for almost 1 year in the other one. They were both studied with fibreoptic laryngoscopy and contrast-enhanced CT and MRI scans. In both cases, the laryngeal biopsy proved negative to Ziehl-Neelsen test, while positive to Koch's bacillus sensitive to rifampicin at PCR test. Both patients completely responded to standard antitubercular antibiotic therapy with rifampicin, isoniazid, pyrazinamide and etambutol protocol.In the differential diagnosis of such patients, laryngeal tuberculosis should be considered due to the reasonable linkage between the immunosuppressant therapy with adalimumab and the tuberculosis infection/reactivation.

Concomitant Use of Elexacaftor/Tezacaftor/Ivacaftor and Etanercept in a Cystic Fibrosis Patient with Juvenile Idiopathic Arthritis

Patients with cystic fibrosis often complain of joint manifestations. However, only a few studies have reported the association between cystic fibrosis and juvenile idiopathic arthritis and addressed the therapeutic challenges of these patients. We describe the first paediatric case of a patient affected by cystic fibrosis, Basedow's disease and juvenile idiopathic arthritis who was contemporarily treated with elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) and anti-tumor necrosis factor α (anti-TNFα). This report seems to reassure regarding the potential side effects of these associations. Moreover, our experience suggests that anti-TNFα is an effective option in CF patients affected by juvenile idiopathic arthritis, and is even safe for children receiving a triple CFTR modulator.

Regional risk of tuberculosis and viral hepatitis with tumor necrosis factor-alpha inhibitor treatment: A systematic review

Background: TNFα inhibitors are regularly used to treat autoimmune diseases. Tuberculosis (TB) and viral hepatitis B are considered potential infectious complications, and screening and surveillance are therefore recommended. Current guidelines do not take into account regional differences in endemicity of these infections. Methods: A systematic literature review of TB and viral hepatitis in patients receiving TNFα-inhibitors was performed, searching in PubMed, Embase, MEDLINE and Web of Science databases. Studies were selected against predefined eligibility criteria and assessed using the Newcastle-Ottawa scale. The number of TB and viral hepatitis cases/1,000 TNFα-inhibitor patients were evaluated, and regional variation compared. Results: 105 observational studies involving over 140,000 patients were included. Overall, 1% of patients developed TB or viral hepatitis B. TB cases/1,000 TNFα-inhibitor patients were 4-fold higher in Asia, Africa, and South America than in Europe, North America, and Australasia where only 0%-0.4% of patients developed TB. Hepatitis B cases/1,000 patients were over 15-fold higher in countries with high prevalence (China, Taiwan, South Korea, Thailand) compared with low prevalence (p < 0.00001) where only 0.4% of patients developed hepatitis B. Only three of 143 patients developed viral hepatitis C, and there was insufficient data to allow regional sub-analysis. Conclusion: TB and viral hepatitis B infections in patients treated with TNFα inhibitors are largely confined to countries with high prevalence of these infections. As only 1/2,500 patients in low prevalence countries treated with TNFα inhibitors develop TB or viral hepatitis B, we suggest an individualized, risk-based approach, rather than universal screening for all patients.

Mycobacterium tuberculosis and Pulmonary Rehabilitation: From Novel Pharmacotherapeutic Approaches to Management of Post-Tuberculosis Sequelae

Tuberculosis (TB) is still a worldwide public health burden, as more than 1.3 million deaths are expected to be reported in 2021. Even though almost 20 million patients have completed specific anti-TB treatment and survived in 2020, little information is known regarding their pulmonary sequelae, quality of life, and their need to follow rehabilitation services as researchers shifted towards proper diagnosis and treatment rather than analyzing post-disease development. Understanding the underlying immunologic and pathogenic mechanisms during mycobacterial infection, which have been incompletely elucidated until now, and the development of novel anti-TB agents could lead to the proper application of rehabilitation care, as TB sequelae result from interaction between the host and Mycobacterium tuberculosis. This review addresses the importance of host immune responses in TB and novel potential anti-TB drugs’ mechanisms, as well as the assessment of risk factors for post-TB disease and usefulness of guidance and optimization of pulmonary rehabilitation. The use of rehabilitation programs for patients who successfully completed anti-tuberculotic treatment represents a potent multifaceted measure in preventing the increase of mortality rates, as researchers conclude that a patient with a TB diagnosis, even when properly completing pharmacotherapy, is threatened by a potential life loss of 4 years, in comparison to healthy individuals. Dissemination of pulmonary rehabilitation services and constant actualization of protocols could strengthen management of post-TB disease among under-resourced individuals.

TNF inhibitors increase the risk of nontuberculous mycobacteria in patients with seropositive rheumatoid arthritis in a mycobacterium tuberculosis endemic area

The aim of this study is to examine the impact of tumor necrosis factor inhibitors (TNFI) on nontuberculous mycobacterium (NTM) infection in rheumatoid arthritis (RA) patients in a mycobacterium tuberculosis (MTB) endemic area. We selected 1089 TNFI-treated RA patients and 4356 untreated RA patients using propensity-matching analysis according to age, gender, and Charlson comorbidity index using the Korean National Health Insurance Service database from July 2009 to December 2010. Both groups were followed-up until the end of 2016 to measure the incidence of mycobacterial diseases. The incidence rate of NTM in TNFI-treated RA group was similar to those of MTB (328.1 and 340.9 per 100,000 person-years, respectively). The adjusted hazard ratio (aHR) of NTM for TNFI-treated RA compared to untreated RA was 1.751(95% CI 1.105-2.774). The risk of TNFI-associated NTM in RA was 2.108-fold higher among women than men. The age-stratified effects of TNFI on NTM development were significantly high in RA patients aged 50-65 years (aHR 2.018). RA patients without comorbidities had a higher incidence of NTM following TNFI treatment (aHR 1.742). This real-world, observational study highlights the need to increase awareness of NTM in TNFI-treated RA patients in an MTB endemic area.

Risk of tuberculosis in patients with rheumatoid arthritis treated with biological and targeted drugs: meta-analysis of randomized clinical trials

BACKGROUND

Concerns exist regarding the potential development of tuberculosis in patients with rheumatoid arthritis (RA) treated with biological and targeted drugs. We assessed systematically whether biological therapy increased the risk of tuberculosis in patients with RA by meta-analysis of randomized controlled trials (RCTs).

METHODS

A systematic literature search was conducted in PubMed, Embase, the Cochrane Library, and China Biology Medicine disc for RCTs evaluating biological therapy in patients with RA from inception through August 2021. Traditional meta-analysis and network meta-analysis were performed to compare the risk of tuberculosis for each biologics class in patients with RA. Peto odds ratio (Peto OR) and its 95% confidence interval (CI) were calculated as the primary effect measure.

RESULTS

In total, 39 studies with 20,354 patients were included in this meta-analysis, and 82 patients developed tuberculosis. The risk of tuberculosis was increased in patients treated with biologics compared with non-biologics (Peto OR: 3.86, 95% CI: 2.36-6.32, P < 0.001). Also, tumor necrosis factor-α (TNF-α) inhibitors had a higher probability of developing tuberculosis than placebo (Peto OR: 3.98, 95% CI: 2.30-6.88, P < 0.001). However, network meta-analysis demonstrated that there was no significant difference in the risk of tuberculosis for each biologics class in patients with RA. Noticeably, tuberculosis was significantly more common in patients treated with a high dose compared with patients receiving a low dose of tofacitinib (Peto OR: 7.39, 95% CI: 2.00-27.31, P = 0.003).

CONCLUSION

This meta-analysis demonstrates the evidence of an elevated risk of tuberculosis in patients with RA treated with TNF-α inhibitors, and a dose-dependent elevated risk of tuberculosis in patients treated with tofacitinib.

Treatment of Autoimmune Diseases with Therapeutic Antibodies: Lessons Learned from PID Patients Allow for Stratification of the Infection Risk

Over the years, a wide variety of therapeutic antibodies has been successfully introduced in the autoimmunology clinic and many more are on the edge to follow. Many of these treatments address either a pathogenic circulating molecule or a cell-bound molecule. Whereas the former target results in neutralization of the soluble factor, the latter target either inhibits cellular function or induces selective cell death. If this targeted molecule or cell is part of the immune system, this therapy evokes a state of immunodeficiency. Knowing the exact function of the respective components enables the risk stratification for possible infectious complications in patients treated with biologics. Much of the understanding of the function of immune cells and their associated molecules, in relation to redundancy in the immune system, is derived from studies in knockout mice. However, as mice are not men in terms of their life-expectancy, their infection exposure, or the composition of their immune system, the most useful knowledge for estimating the consequence of therapeutic intervention on immune competence comes from monitoring patients. In the current chapter, we focus on patients with a primary immunodeficiency (PID) because they provide us with a unique perspective to estimate the redundancy of a certain genetic defect for overall immune competence. These patients have inborn errors of the immune system that, in general, are due to single gene defects. Depending on the immunological pathway that is defective, patients can present with different types of (opportunistic) infectious diseases, as well as other clinical manifestations. Based on selected examples, we focus in this chapter on finding parallels in the infectious risk of autoimmune patients treated with biologics and PID patients with a defect in the immunological pathway that is affected by the respective biologic. The goal is to learn from the (dis)similarities between both patient populations in terms of safety profiles of biologic treatments.

Immunomodulatory Agents for Treatment of Patients with Inflammatory Bowel Disease (Review safety of anti-TNF, Anti-Integrin, Anti IL-12/23, JAK Inhibition, Sphingosine 1-Phosphate Receptor Modulator, Azathioprine / 6-MP and Methotrexate)

PURPOSE OF THE REVIEW

As treatment options for Inflammatory Bowel Disease (IBD) expand each class of medication will have specific safety concerns and side-effect profiles that need to be considered for optimal treatment of patients. We will review the most recent safety data for the newly approved immunomodulator therapies for the treatment of IBD.

RECENT FINDINGS

There are a growing number of publications outlining safety concerns for medications used to treat IBD. We reviewed safety profile of anti-tumor necrosis factor antibodies (TNF) with specific attention to combination therapy (anti-TNF plus immunomodulator). Recent publications have demonstrated increased risk of serious infection and malignancy (lymphoma and overall cancer rates) in patients receiving anti-TNF combination therapy when compared with patients receiving anti-TNF monotherapy or immunomodulator monotherapy. Recent publications on Janus Kinase Inhibitors indicate an increased risk of infection, specifically Herpes Zoster, and increased risk of major cardiovascular events and venous thromboembolic events resulting in a black box warning for the medication. In contrast, anti-interleukin 12/23 agents and gut selective anti-integrin antibody agents have demonstrated a favorable side-effect profile with low rates of infection and malignancy. The latest class of medications to be approved, sphingosine 1-phosphate (S1P) receptor modulators, have cardiac and infectious precautions. The field of IBD treatment is rapidly evolving with several mechanistic classes of medications now available. While corticosteroids continue to be associated with the greatest, overall, safety risks, each of the newer mechanistic classes have unique safety concerns. In the future, as we gain more experience with these agents, we will need to continue to evaluate the safety profile of our therapies used alone or in combination to make informed treatment decisions with our patients.

Targeting Molecular Inflammatory Pathways in Granuloma as Host-Directed Therapies for Tuberculosis

Globally, more than 10 million people developed active tuberculosis (TB), with 1.4 million deaths in 2020. In addition, the emergence of drug-resistant strains in many regions of the world threatens national TB control programs. This requires an understanding of host-pathogen interactions and finding novel treatments including host-directed therapies (HDTs) is of utter importance to tackle the TB epidemic. Mycobacterium tuberculosis (Mtb), the causative agent for TB, mainly infects the lungs causing inflammatory processes leading to immune activation and the development and formation of granulomas. During TB disease progression, the mononuclear inflammatory cell infiltrates which form the central structure of granulomas undergo cellular changes to form epithelioid cells, multinucleated giant cells and foamy macrophages. Granulomas further contain neutrophils, NK cells, dendritic cells and an outer layer composed of T and B lymphocytes and fibroblasts. This complex granulomatous host response can be modulated by Mtb to induce pathological changes damaging host lung tissues ultimately benefiting the persistence and survival of Mtb within host macrophages. The development of cavities is likely to enhance inter-host transmission and caseum could facilitate the dissemination of Mtb to other organs inducing disease progression. This review explores host targets and molecular pathways in the inflammatory granuloma host immune response that may be beneficial as target candidates for HDTs against TB.

Reactivation of latent tuberculosis with TNF inhibitors: critical role of the beta 2 chain of the IL-12 receptor

Tumor necrosis factor (TNF) inhibitors have improved a lot the treatment of numerous diseases, with the well-known example of rheumatoid arthritis (RA). In the early 2000s, postmarketing data quickly revealed an alarming number of severe tuberculosis (TB) under such treatment. These findings were consistent with previous results in mice where TNF is essential for lymph node formation and granuloma organization. The effects of TNF inhibition on RA synovium structure are very similar to those on granuloma, with changes in cellular interactions, cytokine, and chemokine production. In addition to the role of TNF in granuloma, the interleukin (IL)-12/interferon (IFN)-γ pathway is required for an efficient host defense against TB. Primary and secondary immunodeficiencies affecting this pathway lead to severe bacillus Calmette-Guérin (BCG) reaction or full TB. Any chronic inflammation as in RA induces a systemic Th1 defect that predisposes to TB through specific downregulation of the IL-12Rß2 chain. When TNF inhibitors are initiated, this transiently increases this risk of TB, through effects on cellular interactions in a latent TB granuloma. At a later stage, when a better control disease activity is obtained, the risk of TB is reduced but not abrogated. Given the clear benefit from TNF inhibition, latent TB infection screening at baseline is essential for an optimal safety.

The Role of gp130 Cytokines in Tuberculosis

Protective immune responses to Mycobacterium tuberculosis (Mtb) infection substantially depend on a delicate balance within cytokine networks. Thus, immunosuppressive therapy by cytokine blockers, as successfully used in the management of various chronic inflammatory diseases, is often connected with an increased risk for tuberculosis (TB) reactivation. Hence, identification of alternative therapeutics which allow the treatment of inflammatory diseases without compromising anti-mycobacterial immunity remains an important issue. On the other hand, in the context of novel therapeutic approaches for the management of TB, host-directed adjunct therapies, which combine administration of antibiotics with immunomodulatory drugs, play an increasingly important role, particularly to reduce the duration of treatment. In both respects, cytokines/cytokine receptors related to the common receptor subunit gp130 may serve as promising target candidates. Within the gp130 cytokine family, interleukin (IL)-6, IL-11 and IL-27 are most explored in the context of TB. This review summarizes the differential roles of these cytokines in protection and immunopathology during Mtb infection and discusses potential therapeutic implementations with respect to the aforementioned approaches.

Ankylosing spondylitis and psoriatic arthritis: revisiting screening of latent tuberculosis infection and its follow-up during anti-tumor necrosis factor therapy in an endemic area

OBJECTIVES

To retrospectively evaluate the performance and distinctive pattern of latent tuberculosis (TB) infection (LTBI) screening and treatment in patients with ankylosing spondylitis (AS) and psoriatic arthritis (PsA) under anti-tumor necrosis factor (TNF) therapy and determine the relevance of re-exposure and other risk factors for TB development.

METHODS

A total of 135 and 83 patients with AS and PsA, respectively, were evaluated for LTBI treatment before receiving anti-TNF drugs via the tuberculin skin test (TST), chest radiography, and TB exposure history assessment. All subjects were evaluated for TB infection at 3-month intervals.

RESULTS

The patients with AS were more often treated for LTBI than were those with PsA (42% versus 30%, p=0.043). The former also presented a higher frequency of TST positivity (93% versus 64%, p=0.002), although they had a lower frequency of exposure history (18% versus 52%, p=0.027) and previous TB (0.7% versus 6%, p=0.03). During follow-up [median, 5.8 years; interquartile range (1QR), 2.2-9.0 years], 11/218 (5%) patients developed active TB (AS, n=7; PsA, n=4). TB re-exposure was the main cause in seven patients (64%) after 12 months of therapy (median, 21.9 months; IQR, 14.2-42.8 months) and five LTBI-negative patients. TB was identified within the first year in four patients (36.3%) (median, 5.3 months; IQR, 1.2-8.8 months), two of whom were LTBI-positive. There was no difference in the TB-free survival according to the anti-TNF drug type/class; neither synthetic drug nor prednisone use was related to TB occurrence (p>0.05).

CONCLUSION

Known re-exposure is the most critical factor for incident TB cases in spondyloarthritis. There are also some distinct features in AS and PsA LTBI screening, considering the higher frequency of LTBI and TST positivities in patients with AS. Annual risk reassessment taking into consideration these peculiar features and including the TST should be recommended for patients in endemic countries.

Clinical Aspects of Janus Kinase (JAK) Inhibitors in the Cardiovascular System in Patients with Rheumatoid Arthritis

Janus kinase (JAK) inhibitors, a novel class of targeted synthetic disease-modifying antirheumatic drugs (DMARDs), have shown their safety and efficacy in rheumatoid arthritis (RA) and are being intensively tested in other autoimmune and inflammatory disorders. Targeting several cytokines with a single small compound leads to blocking the physiological response of hundreds of genes, thereby providing the background to stabilize the immune response. Unfortunately, blocking many cytokines with a single drug may also bring some negative consequences. In this review, we focused on the activity of JAK inhibitors in the cardiovascular system of patients with RA. Special emphasis was put on the modification of heart performance, progression of atherosclerosis, lipid profile disturbance, and risk of thromboembolic complications. We also discussed potential pathophysiological mechanisms that may be responsible for such JAK inhibitor-associated side effects.

Infections in the Era of Targeted Therapies: Mapping the Road Ahead

Immunosuppressive treatment strategies for autoimmune diseases have changed drastically with the development of targeted therapies. While targeted therapies have changed the way we manage immune mediated diseases, their use has been attended by a variety of infectious complications—some expected, others unexpected. This perspective examines lessons learned from the use of different targeted therapies over the past several decades, and reviews existing strategies to minimize infectious risk. Several of these infectious complications were predictable in the light of preclinical models and early clinical trials (i.e., tuberculosis and TNF inhibitors; meningococcus; and eculizumab). While these scenarios can potentially help us in terms of enhancing our predictive powers (higher vigilance, earlier detection, and risk mitigation), targeted therapies have also revealed unpredictable toxicities (i.e., natalizumab and progressive multifocal leukoencephalopathy). Severe infectious complications, even if rare, can derail a promising therapeutic and highlight the need for increased awareness and meticulous adjudication. Tools are available to help mitigate infectious risks. The first step is to ensure that infection safety is adequately studied at every level of drug development prior to regulatory approval, with adequate post-marketing surveillance including registries that collect real-world adverse events in a collaborative effort. The second step is to identify high risk patients (using risk calculators such as the RABBIT risk score; big data analyses; artificial intelligence). Finally, the most underutilized interventions to prevent severe infections in patients receiving targeted therapies across the spectrum of immune mediated inflammatory diseases are vaccinations.

Is Takayasu arteritis the result of a Mycobacterium tuberculosis infection? The use of TNF inhibitors may be the proof-of-concept to demonstrate that this association is epiphenomenal

Although the association between Takayasu arteritis (TA) and latent or active Mycobacterium tuberculosis infection has been suggested for a long time, studies conducted in recent years are challenging this notion. Until recently, the possibility of a pathogenic relationship between TA and tuberculosis (TB) was considered a medical curiosity, but the advent of tumor necrosis factor (TNF) inhibitors as therapy for recalcitrant TA cases, as well as the widespread use of Bacille Calmette-Guérin (BCG) for vaccination purposes, has relocated this association as a top priority issue. In an attempt to define whether both diseases are pathogenically linked or if their association is only epiphenomenal in nature, we conduct a thorough literature search on the development of TB in patients with TA receiving TNF inhibitors. From a total of 13 studies that included 214 patients, the occurrence of TB was observed only in two individuals exposed to infliximab. This frequency of 0.93% is similar to that encountered in patients with other rheumatic diseases exposed to TNF inhibitors. Finally, we propose a novel pathogenic model that could reconcile the epidemiological, clinical, and immunological evidence that links TA and TB, while providing rationality for the use of TNF inhibitors in patients with TA.