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COMPARISON OF PPD AND QUANTIFERON IN DETERMINING LATENT TUBERCULOSIS IN PATIENTS WHO ARE DIRECTED TO TNF ANTAGONISTS. T.ÇAĞATAY ¹ , M.AYDIN ¹ , Z. GÜLBARAN ¹ , R. YILDIZ ¹ , L. PUR ¹ A.GÜL ¹ , M. İNANÇ ² , S. KAMALI ² , K.KÖKSALAN ³ , Z.KILIÇASLAN ²
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COMPARISON OF PPD AND QUANTIFERON IN DETERMINING LATENT TUBERCULOSIS IN PATIENTS WHO ARE DIRECTED TO TNF ANTAGONISTS T.ÇAĞATAY¹, M.AYDIN¹ , Z. GÜLBARAN¹, R. YILDIZ¹, L. PUR¹ A.GÜL¹, M. İNANÇ ², S. KAMALI², K.KÖKSALAN³, Z.KILIÇASLAN² İstanbul University, Faculty of Medicine Department of Pulmoner Medicine1 İstanbul University, Faculty of Medicine Department of Rheumatology Medicine2 İstanbul University Molecular TB Epidemiology Laboratory 3
Introduction And Aim • TNF antagonist drugs are used in rheumatologic and other inflammatory diseases as the ultimate choice • These drugs increase the risk of infectious diseases especially tuberculosis(TB).
Introduction And Aim • It is crucial to determine latent tuberculosis infection (LTI) before the onset of these drugs. • The decision of prophylaxis has to be made. • Nowadays, PPD is the cheapest and the most easy to perform test to diagnose the latent TB infection.
Introduction And Aim • However, false negative PPD responses decreases the reliability of the test as those patients who are going to use TNF antagonist drugs are in an immunsuppressive state . • Interferon-gamma (IFN-γ) release assays (IGRA’s) have started to be used in recent years for providing more information in the diagnosis of latent infection especially in those patients with an immunocompromised condition
Aim This study is; A pre-statement for the planned research for evaluation of PPD andQuantiferon-TB-Gold testwhich is an IGRA test to diagnose the latent TB infection in the rheumatismal disease group.
Material & Method • Patients are examined for (LTI) prior to TNF antagonist treatment. Before the onset of TNF antagonist drugs who were referred to pulmonary outpatient clinic • 70 patients with rheumatoid arthritis (RA) and ankylosing spondylitis(AS) were taken into this study.
Material & Method • Active TB firstly is exluded by clinic and radiologic methods. • PPD has been performed by standart method after taking blood sample for quantiferon-TB gold.
Statistical Evaluation • “Kappa Test’’ is used for the adjustement of the two tests and • ‘’Logistic Regression’’ analysis is used to show the relation of these two tests by demographic and clinic parameters.
Results AS =31 RA =39
Results PPD Results; • There was no difference in PPD positive and negative groups according to their age and gender. • Positive PPD results were significantly higher in AS patients compared to those with RA (p<0.01). • Positive PPD results of 90% was found in patients with a TB contact (p<0.014). • There was no correlation between the positive PPD results with a sequel in chest X-ray and a BCG scar.
Results Quntiferon Results; • There was no difference between a positive Quantiferon test with age and gender • There was no difference between AS and RA • There was negative Quantiferon results in 92 % of patients with no TB contact history,positive Quantiferon results in 6 of 9 patients with TB contact. • Quantiferon pozitifliği ile PA grafide sekel ve BCG skarı yönünden fark bulunmadı • There was no relation between positive Quantiferon results with a sequel lesion in chest X-ray and BCG scar. • Disease duration was found to be higher in patients with negative Quantiferon tests (p=0.059).
Results • When Quantiferon test is considered the gold standart and 5 mm PPD • Induration is accepted as a positive test ; sensitivity of the PPD was found to be 72% and specifity as 56% and a weak correlation was found between the two methods (kappa=0,27). • If the PPD induration limit would be accepted as 10 mm or higher these ratios would then be 63% and 70% respectively.
Results • 11 patients had BCG scars with indeterminate Quantiferon test results. • For the remainder of 48 patients with BCG scars , when 5 mm or more of an induration was accepted as a positive PPD test then the reliability of the test was lowered to 50%.
Conclusion • It is indicated that Quantiferon TB- GoldTest is more sensitive to identify the latent TB infection in immunesupressive patients • It is not affected by the BCG and atypical mycobacterial infections.
Conclusion • For the diagnosis of latent TB infection in immunesuppressive patients who are going to take TNF antagonist drugs PPD results and Quantiferon results showed a weak correlation. • If the Quantiferon results are accepted as the correct ones then there seems to be an important rate of trouble with our decisions of prophylaxis on the basis of PPD tests.
Conclusion • However as there are 15% of indeterminate results in all of our patients with BCG scars, this shows also the limitation of the Quantiferon Test.
Conclusion • There is a need for more number of studies with lot of patients to be done but these preliminary results show the need of IGRA Test performances in diagnosing the latent TB infection in the group of patients with Rheumatismal diseases.