Diagnostic value of serum adenosine deaminase levels in sputum smear negative pulmonary tuberculosis patients in Nepalese population

Abstract

ObjectiveTo assess the levels of adenosine deaminase (ADA) in serum in patients with sputum smear negative pulmonary tuberculosis (SNPTB) and to compare it with serum ADA levels in patients with non-tuberculous pulmonary disease – chronic obstructive pulmonary disease (COPD) and with healthy control group and to explore its validity as a diagnostic marker in serum in SNPTB patients. MethodsThree groups of study populations were made. Group I: SNPTB – 142 cases, Group II: non-tubercular pulmonary disease – COPD – 40 cases, Group III: healthy controls – 80 cases. Serum samples were collected and ADA assay was done by the method of Guisti and Galanti. ResultsADA levels (Mean±SD, U/L) in the three groups were as follows: Group I: 42.26±21.22, Group II: 23.31±8.22, Group III: 18.88±6.67. Difference between Group I and Group III was statistically significant (P < 0.0001). The test showed a high specificity 91.25% (95% confidence interval – CI 83.00 – 95.7) and a sensitivity of 83.10% (95% CI 76.08-88.37) in Group I. Positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio and accuracy in Group I were 94.00%, 69.52%, 9.49, 0.18 and 82.43% respectively. ConclusionsOverall assessment of the use of serum ADA levels as a diagnostic biochemical marker in smear-negative pulmonary tuberculosis patients showed promising results. Studies with a larger population group are required to validate its use as a routine diagnostic test in these cases.