AB1318 VALUE OF NEW BIOMARKERS IN THE DIFFERENTIAL DIAGNOSIS OF SARCOIDOSIS AND TUBERCULOSIS
Authors: B Harikrishnan, C B. Mithun, Jyothi V. Srikanth, Renjitha Bhaskaran
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background:</h3> Due to multisystem involvement with almost similar presentation, tuberculosis (TB) and sarcoidosis poses a diagnostic challenge. As both of them show granulomatous inflammation in tissue, even histopathological examination is not helpful to differentiate the two. As a result of this difficulty, new biomarkers for differentiating the two are being investigated. Previous studies (1,2) done in other regional population attempted to show the efficacy and role of Neutrophil by lymphocyte ratio (NLR) and platelet/lymphocyte ratio (PLR) to differentiate sarcoidosis from TB, with inconsistent results. We attempt to see if these biomarkers can be used in our population to differentaite the two. <h3>Objectives:</h3> The aim of our study was to investigate the value of neutrophil/lymphocyte ratio (NLR), and platelet/lymphocyte ratio (PLR) to differentiate TB from sarcoidosis. In addition, we also studied Neutrophil/lymphocyte/albumin/globulin ratio (NLR by A:G ratio) as a novel marker for differentiating the two. <h3>Methods:</h3> Patients recruited for the study were selected retrospectively from hospital records during the period of September 2017 to December 2018: 50 consecutive pulmonary TB patients diagnosed based on sputum acid–fast bacilli (AFB) positivity and/or culture–positivity 39 consecutive patients diagnosed with sarcoidosis by an experienced Rheumatologist on clinical and histological grounds. 50 consecutive healthy subjects who presented to general comprehensive check up on Monday of every week. Subjects who were having any autoimmune disease or infections were excluded. We collected the information including clinical and biochemical parameters at the time of presentation, from the hospital records. NLR, NLR by A:G ratio and PLR were calculated. To test the statistical significance of continuous variables between sarcoid and tb student's t test/Mann Whitney U test was used. To find the cut off value of study variables, ROC curve was used. Diagnostic measures like sensitivity, specificity, predictive values and accuracy was computed. <h3>Results:</h3> Though age was comparable, sex ratio varied between groups with more females in sarcoidosis group. Leukocyte count and neutrophil percentage, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), NLR, NLR by A:G and PLR were significantly higher in the TB group compared with sarcoidosis (for all parameters P &lt; 0.001). Table showing ROC analysis results and accuracy rates of NLR, NLR by A:G ratio and PLR in detection of tuberculosis among sarcoidosis and tuberculosis groups <h3>Conclusion:</h3> TB vs sarcoidosis is a challenging diagnostic dilemma. Our retrospective study shows the role of NLR, NLR by A:G ratio and PLR in differentiating TB from sarcoidosis. These biomarkers can help to guide our clinical judgement in differentiating these two causes of granulomatous inflammation. <h3>References</h3> [1] Iliaz S, Iliaz R, Ortakoylu G, Bahadir A, Bagci BA, Caglar E. Value of neutrophil/lymphocyte ratio in the differential diagnosis of sarcoidosis and tuberculosis. Annals of thoracic medicine. 2014 Oct;9(4):232. [2] Ozdemir C, Sökücü SN, Önür ST. Can neutrophil/lymphocyte ratio and platelet/lymphocyte ratio be used in differential diagnosis of stage I sarcoidosis from tuberculosis lymphadenopathy?. Eurasian Journal of Pulmonology. 2018 Jan 1;20(1):22. <h3>Disclosure of Interests:</h3> None declared