IGRA testing in patients with immune-mediated inflammatory diseases: which factors influence the results?

Diagnosis of latent tuberculosis infection in patients with immune-mediated inflammatory chronic diseases (IMIDs) can be challenged as diagnostic test reliability could be impaired by immunosuppression. We retrospectively analyzed the Quantiferon Gold-Test in-Tube (QFT-G-IT) results of all patients with IMIDs seen at the Department of Internal Medicine of Son Llàtzer Hospital, Palma de Mallorca (Spain), looking for the factors related to QFT-G-IT indeterminate results. During the study period (2008-2015), 520 patients met the inclusion criteria. Factors associated with indeterminate QFT-G-IT results in a univariate analysis were inflammatory bowel disease, disease activity, lymphopenia, and medium-to-high doses of corticosteroids. In a subsequent multivariate analysis, only lymphopenia (defined as < 1500 cells) was associated with indeterminate QFT-G-IT results. Lymphocyte count was the only factor independently associated with an increased number of indeterminate QFT-G-IT results in patients with different autoimmune diseases. Others factors such as the use of medium-to-high doses of corticosteroids should be considered before testing with QFT-G-IT.

[Symptomatic acute Q fever: a series of 87 cases in an area of Mallorca]. / Fiebre Q aguda sintomática: 87 casos en un área de Mallorca.

INTRODUCTION: Q fever is a widespread zoonotic infection caused by Coxiella burnetii (C. burnetii). Acute infection varies from a self-limited flu-like illness to pneumonia or hepatitis. METHODS: A retrospective case study from March 2003 to December 2011 was conducted in the Hospital Son Llàtzer in Palma de Mallorca. Acute Q-fever was diagnosed in a patient with clinical suspicion and IgM in phase ii positive (≥ 1/40), with a positive IgG (≥1/80), or when IgG seroconversion was observed during convalescence. A total of 87 cases of acute Q fever were diagnosed. The median age was 50 years (range 21-89), and 69 (79.3%) were male. Fever and headache were the most common symptoms. Pneumonia was diagnosed in 39 (44.8%) patients, febrile episode in 21 (24.1%), and acute hepatitis in 23 (25.6%). Increased serum transaminases were observed in 19 (21.8%). Doxycycline was prescribed in 29 cases (33.4%). There were 30 (34.5%) patients lost to follow up after hospital discharge. A favorable outcome was observed in all other cases. Only one new case progressed to chronic Q fever. RESULTS: A total of 87 cases of acute Q fever were diagnosed. The median age was 50 years (range 21-89), and 69 (79.3%) were male. Fever and headache were the most common symptoms. Pneumonia was diagnosed in 39 (44.8%) patients, febrile episode in 21 (24.1%), and acute hepatitis in 23 (25.6%). Increased serum transaminases were observed in 19 (21.8%). Doxycycline was prescribed in 29 cases (33.4%). There were 30 (34.5%) patients lost to follow up after hospital discharge. A favorable outcome was observed in all other cases. Only one new case progressed to chronic Q fever. CONCLUSION: Acute Q fever acute is common our environment. Pneumonia was the most common clinical presentation. Even although doxycycline was prescribed in a small number of patients, a favorable outcome was observed in all cases.

Use of Quantiferon-TB-Gold in Tube(®) test for detecting latent tuberculosis in patients considered as candidates for anti-TNF therapy in routine clinical practice.

BACKGROUND/METHODS: Quantiferon-TB-Gold in Tube(®) test (QFT-G-IT) may have advantages if combined with TST when screening for Latent Tuberculosis Infection (LTBI) prior to initiating anti-TNF therapy in an area of intermediate tuberculosis incidence such as Spain. In a small-scale prospective study, we evaluate the use of QFT-G-IT in combination with the screening recommended in Spain (Tuberculin-Skin Test, TST retest, clinical data, and Chest X-Ray (CXR)) for LTBI in patients considered as candidates for anti-TNFα treatment. RESULTS: From June 2008 to October 2010, 123 patients from a 300-bed hospital in Palma de Mallorca (Spain) were included in the study. The majority of patients were under immunosuppressive therapy. A positive TST and TST booster were found in 22 and 17 patients, respectively. Thus 39 (31.7%) of the 123 patients had a positive TST. QFT-G-IT was positive in 16 patients (13.6%), indeterminate in 4 (3.2%), and negative in 103 (83.7%). One of the two tests was positive and LTBI was diagnosed in 34.1% of patients. The agreement between TST and QFT-G-IT among vaccinated patients was low and not statistically significant (Kappa=0.15) and was almost perfect among non-BCG vaccinated patients (K=0.81). TST positive responses were significantly related to BCG-vaccination (p<0.05) and QFT-G-IT positive response rates were related to older age (p<0.05). CONCLUSION: QFT-G-IT may have advantages when combined with TST in immunosuppressed patients especially in older patients with a negative TST; in BCG vaccinated patients with a positive TST, QFT-G-IT could avoid unnecessary treatments and toxicities related to a false-positive TST result.

[Quantiferon-TB Gold In-Tube test in the diagnosis of pulmonary and extra-pulmonary tuberculosis]. / Valor de QuantiFERON-TB Gold Test in Tube en el diagnóstico de tuberculosis pulmonar y extrapulmonar.

INTRODUCTION: The Interferon-γ in vitro detection tests could be a useful tool in the diagnosis of active tuberculosis compared to Mycobacterium tuberculosis (MTB). METHODS: The QuantiFERON-TB-Gold in Tube (QFG-IT) test was performed on the blood of 118 patients with active tuberculosis and the results compared with the tuberculin test. RESULTS: The QFG-IT test was positive in 94 cases (79.7%), negative in 17 (14.4%) and indeterminate in 7 (5.9%). A negative or indeterminate QFG-IT test was more common in older patients (P=0.017) and in cases with negative smear tests (P=0.041). The kappa agreement between the tuberculin and QFG-IT tests was 74.5% with a kappa value of 0.45 (SE:0.136). Thirteen of the patients studied were infected with HIV and the tuberculin was positive in 5 of the 12 cases (38.5%) in whom it was performed, with the QFG-IT being positive in 9/13 (69.2%). CONCLUSIONS: The QFG-IT test may be a useful complimentary tool to the tuberculin test in the diagnosis of tuberculosis.

Role of QuantiFERON(®)-TB Gold In-Tube in tuberculosis contact investigation: experience in a tuberculosis unit.

BACKGROUND: Interferon-γ release assays (IGRAs) are increasingly used for the diagnosis of latent tuberculosis infection (LTBI). Because of the lack of a gold standard for the diagnosis of LTBI, IGRAs are compared to the tuberculin skin test (TST) and yield conflicting results. We assessed the usefulness of an IGRA test, QuantiFERON(®)-TB Gold In-Tube (QFT-G-IT), for diagnosing LTBI compared with TST in the setting of a contact screening study. METHODS: A prospective comparison between the QFT-G-IT and the TST in TB contact subjects in a low TB burden area was conducted sequentially between January 2006 and December 2012. RESULTS: A moderate concordance between the two tests (κ = 0.44 for TST cut-off of 5 mm and κ = 0.56 for TST cut-off of 15 mm) was found. A better agreement was shown in younger contacts and in non-vaccinated contacts when using a TST of 15 mm. Independent risk factors for a TST(+)/QFT-G-IT(-) discordance were history of BCG vaccination and age between 31 and 59 years. Discordance was also more frequent using a TST cut-off value of 5 mm. QFT-G-IT(+)/TST(-) was infrequent and was found in older contacts. CONCLUSIONS: Based on our data, we cannot recommend the use of QFT-G-IT as the only test to rule out LTBI, especially in older patients.

Experience of a monographic tuberculosis unit: the first 500 cases.

INTRODUCTION: Tuberculosis (TB) remains a highly prevalent and potentially severe disease. However, since 2002 the annual incidence has been decreasing both worldwide and in Spain, where the incidence varies widely between regions. The main objective of this study is to describe the experience of a monographic TB unit in a second level hospital. PATIENTS AND METHODS: A descriptive study was carried out which included all cases of TB diagnosed in a monographic unit of a secondary hospital between 2003 and 2011. Demographic, clinical, epidemiological and microbiological data were recorded. RESULTS: We analyzed 500 TB cases and found an increasing annual incidence in all subgroups, including native and immigrant populations. Most cases (63.8%) were male, with a median age of 36 years (range 8 months-90 years). In total, 39.8% of patients were foreign born. Coinfection with human immunodeficiency virus was found in 11% of cases. The pulmonary form was most frequently diagnosed (63.8%). Overall mortality was 5.8% with no significant differences between groups (including foreign born and human immunodeficiency virus positive patients). CONCLUSIONS: Although TB incidence is globally decreasing, in our study we found an increasing number of cases in recent years in all subgroups, which can be explained by this being a monographic unit with an intensive contact tracing program.