LYMPHOCYTE-NEUTROPHIL RATIO IN THE DIAGNOSIS OF TUBERCULAR PLEURAL EFFUSION IN A TERTIARY CARE CENTRE: A DESCRIPTIVE CROSS SECTIONAL STUDY

1* 2 3 Rajneesh Jha , Ram Kumar Mehata , Puru Koirala


Introduc on
Tuberculosis is a common infec on in our community. Tubercular pleural effusion is the second most common form of extrapulmonary tuberculosis. Among the several causes of exuda ve pleural effusison tubercular remains the most common form in clinical prac ce. The aim of this study was to evaluate the significance of lymphocyte-neutrophil ra o(LN ra o) in cases of exuda ve effusion for diagnosis of tubercular effusion.

Methodology
This was a hospital based cross sec onal study done in st Pa ents at ter ary care hospital from 1 September 2020 to st 1 april 2021 a er taking ethical clearance from ins tu onal reviw commi ee. Convienience sampling was done. Sta s cal Analysis of data like percentages and frequencies were used for categorical variables. Mean and SD (standard devia on) were used for describing con nuous variables. Inferen al sta s cal tools like Chi-Square test and Student's t-test were used. P-value of <0.05 was considered sta s cally significant.
Result out of 200 cases 75% were tubercular pleural effusion and these cases were found have high levels of LN ra o (0.89 ± 0.11 for females and 0.97 ± 0.14 for males) and ADA (137.79 ± 44.61for females and 147.61 ± 51.64 for males) and more than 90% sensi vity and specificity of LN ra o and ADA level.

Conclusion
Exuda ve pleural fluid L/N ra o >0.75 is an efficient means of diagnosing tuberculous pleural effusion and its combina on with ADA level gives us more accuracy and surety about the diagnosis of tubercular pleural effusion.

INTRODUCTION
Pleural effusion is defined as the abnormal collec on of fluid in the pleural cavity. It is classified into transudates and 1 exudates based on the Light's criteria. Common causes of exuda ve pleural effusions found in clinical prac ces are tuberculosis, para pneumonic, malignancy primary or metastasis, associated with collagen vascular disease, liver 2 abscess, subphrenic abscess, pancrea s. Tuberculous pleural effusion is seen in many cases in our region. Tuberculosis has high prevalence in asian countries like Nepal anad India. It is the one of the most common form of 3 extra pulmonary tuberculosis. It becomes challenging for a clinician many a mes to diffren ate the causes for pleural effusion. First of all we have to differen ate transuda ve effusion from exuda ve effusion. Then it is essen al to find out diagnosis for underlying cause of exuda ve effusion. For this purpose several biochemical parameters like adenosine deaminase (ADA), lactate dehydrogenase (LDH), C-reac ve protein (CRP), interferon gamma and procalcitonin levels, have been [4][5][6] studied, but its diagnosis is s ll challenging. However adenosine deaminase (ADA) is being frequently used as a diagnos c maker in tuberculous pleural effusion in many centres in our region. ADA derived from the summary receptor operator curve with cut off value >40U/L is found to be more [7][8] than 90% both sensi vite and specific. Lymphocyteneutrophil ra o (LN ra o) is being inves gated as novel inflammatory marker nowadays. The associa on of lymphocyte-neutrophil ra o and lung cancer has been mostly inves gated among studies on lung diseases , and a few studies have inves gated its values in the pleural fluid for the differen al diagnosis of bacterial pneumonia and 9-10 tuberculous pleural effusion. Aim of the study was to find out the role of the lymphocyte neutrophil ra o (LNR) which can be easily obtained by determining the total and differen al cell counts of pleural fluid for the diagnosis of exuda ve pleural effusion as tubercular in origin.

METHODOLOGY
It was a single centre hospital based descrip ve cross sec onal study. It was conducted in Birat medical college st and teaching hospital, biratnagar, Nepal from September 1 st 2020 to april 1 2021. The study included 200 pa ents aged more than 15 years giving consent to be enrolled in the study. Prior to the the study ethical clearance was taken from IRC. Sample size calcula on was obtained by using the formula, 2 2 Sample Size (N) = (1.96) X P (1-P) / M Where, P = Prevalence of the disease in the locality; M = Margin of error (5%) .The prevalence of tuberculous pleural effusion has been reported to be variable in different countries. prevalence varies in asaian and non asian countries. Nepal as an asian country has a higher prevalence reate. Prevalence in asian countries is usually 10-20% by various studies. (11)(12) keeping a prevalence of 15%, the sample size was calculated 196. So, sample size of 200 was considered in this study.  When we compared the samples dividing it into two major groups as tuberculous and nontubercoulous we found that most of the tuberculous samples had both ADA>40U/L and LN ra o>0.75 together while most of the nontuberculous samples had both ADA<40U/L and LN ra o<0.75 together.

DISCUSSION
Pleural effusion is common respiratory problem in our clinical prac ce. Many cases with fever, cough, dyspnoea visi ng our outpa ent department or admi ed in medical ward through emergency are found to have pleural effusion. The most common causes of exuda ve pleural effusion include pneumonia, tuberculosis and cancer .The diagnos c dilemma many a mes alter the course of management. Pneumonia responds to limited course of an bio cs, while tuberculosis needs long term an tubercular drugs according to na onal tuberculosis program while lung cancer has different protocol like surgery, chemo and radiotherapy. Cases like pleural effusion associated with pancrea s , rheumatoid arthri s, liver abscess respond only when underlyind causes are treated. Hence diagnosis of exuda ve pleural effusion is of utmost importance. Although many biochemical parameters, such as adenosine deaminase, lactate dehydrogenase, C-reac ve protein, adenosine deaminase, interferon gamma and procalciton in levels, have been studied in the context of the diagnosis of exuda ve pleural effusion, its diagnosis is s ll challenging. 13 As we know prevalence of tuberculosis is high in Nepal and it can present in two forms either pulmonary or extra pulmonary.

CONCLUSION
From the above discussion, it is concluded that pleural fluid L/N ra o >0.75 is an efficient means of diagnosing tuberculous pleural effusion and its combina on with ADA level gives us more accuracy and surety about the diagnosis of tubercular pleural effusion.

LIMITATIONS OF THE STUDY
The sample was taken from a medical college of eastern Nepal, so it may not be totally applicable to other regions . Moreover, larger sample size could have given li le different results. Calcula on of LNR values seemed to be more helpful in tubercular pleural effusion compared to malignant, parapneumonic and para-malignant effusions, so the poten al use of this formula may be limited to countries with high TB incidence. An addi onal limita on of our study was that we only used LNR values; adding other parameters, such as, CRP levels, TB IgM to the evalua on could be more helpful for differen al diagnosis.