Factors affecting pleural fluid adenosine deaminase level and the implication on the diagnosis of tuberculous pleural effusion: a retrospective cohort study

Abstract

BackgroundAdenosine deaminase (ADA) is useful in the diagnosis of tuberculous pleural effusion (TPE). This study aims to determine the factors affecting pleural fluid ADA levels and to establish the optimal ADA levels for diagnosis of TPE for different age groups.MethodsThis was a retrospective study from January 2007 to October 2011. One hundred and sixty patients who had pleural fluid ADA performed for investigation of pleural effusion were analyzed. Variables examined included demographics, pleural fluid characteristics and peripheral blood counts. The ADA cut-offs according to age were selected using the receiver operating characteristic (ROC) curve.ResultsThe mean pleural fluid ADA was significantly higher in the TPE group (100 ± 35 IU/L) compared to non TPE patients (30 ± 37 IU/L). There was significant correlation between pleural fluid ADA and age, pleural fluid protein, LDH, and fluid absolute lymphocyte count. The strongest correlation was seen with age (r = −0.621). For patients ≤ 55 years old the ROC for ADA had area under curve (AUC) of 0.887. A pleural fluid ADA of 72 IU/L had sensitivity of 95.1%, specificity of 87.5%, positive predictive value (PPV) of 95.1% and negative predictive value (NPV) of 87.5% for the diagnosis of TPE. For patients > 55 years old the AUC is 0.959. ADA of 26 IU/L had a sensitivity of 94.7%, specificity of 80.4%, PPV of 62% and NPV of 97.8%.ConclusionsThere is a significant negative correlation between pleural fluid ADA and age. For older patients, a lower ADA cut-off should be used to exclude TPE.

Atypical Pleural Fluid Profiles in Tuberculous Pleural Effusion: Sequential Changes Compared with Parapneumonic and Malignant Pleural Effusions

“…The low ADA levels in lymphocytic TPE might be somewhat different from those in neutrophilic TPE, which usually occur in the early stages of the disease, in terms of the host immune response. For example, patients with lymphocytic TPE with low ADA levels may have underlying problems related to pleural fluid ADA production, such as old age (20,21), smoking (21), or a genetic defect, unlike those with early neutrophilic TPE with low ADA levels. The present study showed that the low ADA levels in lymphocytic TPE patients subsequently increased as the disease progressed, regardless of potential underlying problems associated with low ADA levels.…”

Diagnostic Cut-Off of Pleural Fluid Adenosine Deaminase (Ada) Value in Tuberculous Pleural Effusion

“…A study done by Tay, Tee et al concluded that the cut-off level of ADA for diagnosing tuberculous pleural effusion was different in different age groups (72 IU/L in < 55 years and 26 IU/L in > 55 years' age group). 10 The same study also analysed other variables that can affect the pleural fluid ADA level. Though the strongest correlation was with age, other factors like pleural fluid protein, LDH and fluid lymphocyte count also were found to influence the level of ADA.…”

Utility of pleural fluid routine and microscopy examination plus adenosine deaminase levels in the diagnosis of tuberculous pleural effusion

“…There is a significant negative correlation between pleural fluid ADA and age. [12] Elevated lymphocytes to neutrophils together with high ADA levels were the most useful parameters in diagnosing tuberculous pleural effusion. This finding was consistent with some of the previous studies.…”