To the Editor
We read with great interest the well-presented review article titled ‘Tuberculous pleural effusion: diagnosis & management’ published in the Expert Review of Respiratory Medicine by Antonangelo et al reviewing the diagnosis and management of tuberculous pleurisy (TP) [Citation1]. This article indicated the highly beneficial usage of adenosine deaminase (ADA) activity in lymphocytic pleural effusions (PEs) for TP diagnosis, especially in medium and high prevalence regions.
We have previously emphasized the benefits of this biomarker along with other biological parameters, confirming the diagnostic significance of ADA measurement in diagnosis and management of lymphocytic PEs in intermediate and high TB prevalence areas [Citation2–Citation7].
In 2017, the incidence of tuberculosis for Greece was 4.5 cases per 100.000 people [Citation8]. However, the exact prevalence of TP is not known in Greece. As the region’s only tertiary care referral Center for tuberculosis, our department serves a larger area for other four rural hospitals in Central Greece. Analysis of ADA activity is one of the most studied possibilities performed; however, exclusively in our Center. According to a 6-year retrospective study (June 2013- June 2019) regarding the use of ADA as a diagnostic tool for TP, we found that by selecting the 40 U/L as a cutoff for over 1500 PE lymphocytic samples, 9% of them had ADA values above this limit and ADA had significantly contributed to TP diagnosis in these cases. Furthermore, our archives exhibited a higher than 10% prevalence of TP amongst TB infected patients.
As far as the rest of the regional secondary healthcare hospitals in Central Greece are concerned, they provided only 130 lymphocytic samples altogether over the six-year period. Notably, these hospitals are staffed by internists who are responsible for investigating the etiology of PE and no respiratory physicians. After applying the cutoff ADA value of 40 U/L, we found that pleural samples with higher ADA levels than the limit were notably more in those regions providing fewer samples for analysis. Specifically, positive ADA levels displayed higher percentages ranging from 12% to 24% (mean ADA value: 67.6 ± 24.5 U/L)
Our results indicate that although ADA is highly utilized by respiratory physicians when lymphocytic PEs are managed, internists do not widely include this biomarker in the diagnostic algorithm of lymphocytic PEs even they are informed of the ADA usefulness in TP diagnosis. Therefore, a stronger cooperative network with vertical links among internists and respiratory physicians is essential for proper medical diagnosis and management of TP cases.
Declaration of interest
The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript.
Additional information
Funding
References
- Antonangelo L, Faria CS, Sales RK. Tuberculous pleural effusion: diagnosis & management. Expert R. Respir Med. 2019;8:747-759.
- Apostolidou E, Tsilioni I, Hatzoglou C, et al. Pleural transport physiology: insights from biological marker measurements in transudates. Open Respir Med J. 2011;5:70–72.
- Gourgoulianis KI. Diagnostic value of adenosine deaminase activity in tuberculous effusions. Eur Respir J. 1990;3:1098.
- Skouras VS, Magkouta SF, Psallidas I, et al. Interleukin-27 improves the ability of adenosine deaminase to rule out tuberculous pleural effusion regardless of pleural tuberculosis prevalence. Infect Dis (Auckl). 2015;47:477–483.
- Gerogianni I, Papala M, Tsopa P, et al. Could IFN-γ predict the development of residual pleural thickening in tuberculous pleurisy? Monaldi Arch Chest Dis. 2016;69:18–23.
- Kotsiou OS, Tzortzi P, Beta RAA, et al. Repeatability of pleural adenosine deaminase measurements in diagnostic evaluation of pleural effusions. J Clin Lab Anal. 2018;32:e22371.
- Daniil ZD, Zintzaras E, Kiropoulos T, et al. Discrimination of exudative pleural effusions based on multiple biological parameters. Eur Respir J. 2007;30:957–964.
- World Health Organization (WHO). Tuberculosis country profiles. WHO; 2019c. [updated 2019 Jul 17]. Available from: https://www.who.int/tb/country/data/profiles/en/