BACKGROUND Adenosine deaminase (ADA) activity is typically elevated in patients with tuberculous pleural effusion (TPE), but low ADA has occasionally been reported in patients with TPE. The characteristics of these patients are not well-known, and erroneous exclusion of the possibility of TPE can result in a delayed diagnosis. This study investigated the characteristics of patients with TPE who had low ADA activity. METHODS We retrospectively reviewed patients with microbiologically or pathologically confirmed TPE between 2012 to 2018 in a tertiary hospital in South Korea. Patients were categorised into two groups: high ADA (≥40 IU/L) and low ADA (< 40 IU/L). Clinical characteristics and Sequential Organ Failure Assessment (SOFA) scores were compared between groups. RESULTS A total of 192 patients with TPE were included; 36 (18.8%) had ADA < 40 IU/L with a mean ADA activity level of 20.9 (±9.2) IU/L. Patients with low ADA were older (75.3 vs. 62.0 years, p < 0.001) and had a lower mean lymphocyte percentage (47.6% vs. 69.9%, p < 0.001) than patients with high ADA. Patients in the low ADA group had a significantly higher mean SOFA score (2.31 vs. 0.68, p < 0.001), and patients with organ dysfunction were significantly more common in the low ADA group (p < 0.001). Patients with 2 or ≥ 3 organ dysfunctions constituted 19.4 and 13.9% of the patients in the low ADA group, whereas they constituted 7.1 and 1.3% of the patients in the high ADA group (p < 0.001). Multivariate logistic regression analyses showed that older age (odds ratio = 1.030, 95% confidence interval 1.002-1.060, p = 0.038) and a higher SOFA score (odds ratio = 1.598, 95% confidence interval 1.239-2.060, p < 0.001) were significantly associated with low ADA activity in patients with TPE. CONCLUSIONS ADA activity can be low in patients with TPE who are elderly, critically ill, and exhibit multiorgan failure. Low ADA activity cannot completely exclude the diagnosis of TPE, and physicians should exercise caution when interpreting pleural fluid exams.

中文翻译：

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对于患有多器官功能衰竭的老年危重病人，结核性胸膜炎中的胸水ADA活性可能较低。

背景技术在结核性胸腔积液（TPE）患者中，腺苷脱氨酶（ADA）活性通常升高，但在TPE患者中偶有报道ADA降低。这些患者的特征尚不为人所知，错误排除TPE的可能性会导致诊断延迟。这项研究调查了具有低ADA活性的TPE患者的特征。方法我们回顾性研究了2012年至2018年间在韩国三级医院经微生物学或病理学证实为TPE的患者。患者分为两组：高ADA（≥40 IU / L）和低ADA（<40 IU / L）。比较两组之间的临床特征和顺序器官衰竭评估（SOFA）得分。结果共纳入192例TPE患者。36（18。8％）的ADA <40 IU / L，平均ADA活性水平为20.9（±9.2）IU / L。ADA低的患者年龄较大（75.3 vs. 62.0岁，p <0.001），并且平均淋巴细胞百分比低于高ADA的患者（47.6％vs. 69.9％，p <0.001）。低ADA组的平均SOFA评分显着较高（2.31比0.68，p <0.001），器官功能障碍的患者在低ADA组中更为常见（p <0.001）。器官功能低下的患者中有2个或≥3个的患者分别占低ADA组患者的19.4％和13.9％，而分别占高ADA组患者的7.1％和1.3％（p <0.001）。多元logistic回归分析显示，年龄较大（赔率= 1.030，95％置信区间1.002-1.060，p = 0.038）和较高的SOFA评分（赔率= 1.598，TPE患者的95％置信区间1.239-2.060，p <0.001）与ADA活性低显着相关。结论老年，危重病和多器官功能衰竭的TPE患者的ADA活性可能较低。ADA活性低不能完全排除TPE的诊断，医生在解释胸水检查时应谨慎行事。