Clinical characteristics and potential indicators for definite diagnosis of tuberculous pleural effusion

Figures & data

Table 1. The clinical characteristics of the study subjects.

Characteristics	Total	TBPE	MPE	Empyema		PPE	Miscellaneous causes	p
Number	77	30 (38.96%)	19 (24.67%)	6 (7.79%)		10 (12.99%)	12 (15.58%)
Demographic characteristics
Age (years)	55.80 ± 21.60	42.00 ± 21.10	66.10 ± 15.98*		58.50 ± 7.58	70.00 ± 21.04*	60.83 ± 18.04*	<.001
Gender								.404
male	60 (77.92%)	20 (66.7%)	17 (89.5%)		5 (83.3%)	8 (80%)	10 (83.3%)
female	17 (22.08%)	10 (33.3%)	2 (10.5%)		1 (16.7%)	2 (20%)	2 (16.7%)
Pleural fluid analysis
Mycobacterium tuberculosis DNA detection								.001
positive	10 (13.0%)	10 (33.3%)	0 (0.0%)		0 (0.0%)	0 (0.0%)	0 (0.0%)
negative	67 (87.0%)	20 (66.7%)	19 (100%)		6 (100%)	10 (100%)	12 (100%)
ADA (U/L)	47.29 ± 65.11	53.79 ± 50.86	39.28 ± 57.81		164.42 ± 122.03*	19.99 ± 12.59	7.91 ± 4.90*	<.001
ADA ≥ 40	25 (32.5%)	15 (50%)	4 (21.1%)		5 (83.3%)	1 (10%)	0 (0.0%)
ADA < 40	52 (67.5%)	15 (50%)	15 (78.9%)		1 (16.7%)	9 (90%)	12 (100%)
Total protein (g/L)	41.68 ± 14.83	49.78 ± 9.77	42.93 ± 9.74*		40.52 ± 15.12	42.00 ± 9.02	21.37 ± 17.67*	<.001
Chlorine (mmol/L)	106.04 ± 17.42	109.59 ± 26.39	104.87 ± 6.93		97.22 ± 4.39	100.98 ± 4.62	107.64 ± 7.50	.440
Glucose (mmol/L)	5.41 ± 3.26	4.11 ± 2.25	6.31 ± 3.42*		0.98 ± 0.60*	7.15 ± 2.76*	7.98 ± 2.78*	<.001
LDH (U/L)	2333.17 ± 7353.06	1319.85 ± 3466.18	1564.26 ± 2454.90		17214.20 ± 20911.60*	574.53 ± 715.58	111.42 ± 123.75	<.001
LDH distribution								.001
LDH ≥ 500 (U/L)	31 (40.3%)	13 (43.3%)	9 (47.4%)		6 (100%)	3 (30%)	0 (0%)
LDH < 500 (U/L)	46 (59.7%)	17 (56.7%)	10 (52.6%)		0 (0%)	7 (70%)	12 (100%)
Blood detection
LDH (U/L)	280.00 ± 265.13	220.29 ± 66.46	415.70 ± 495.26*		198.70 ± 92.04	258.31 ± 142.89	271.54 ± 77.43	.122
Total protein (g/L)	65.04 ± 9.12	69.64 ± 7.47	62.64 ± 8.49*		64.52 ± 7.76	61.53 ± 6.63	60.55 ± 12.06	.007
Lymphocyte (×10^9/L)	1.12 ± 0.69	0.99 ± 0.47	1.12 ± 0.98		1.44 ± 0.67	1.13 ± 0.53	1.25 ± 0.74	.608
CRP (mg/L)	47.46 ± 49.56	43.26 ± 40.02	58.17 ± 69.16		71.23 ± 43.23	50.50 ± 40.07	26.25 ± 40.36	.323
T-SPOT.TB A	18.63 ± 20.94	30.31 ± 22.12	11.50 ± 14.40*		15.50 ± 21.48	5.30 ± 14.02*	12.58 ± 18.23*	.002
T-SPOT.TB B	18.01 ± 22.21	29.59 ± 25.33	7.44 ± 15.18*		22.17 ± 34.53	5.00 ± 12.69*	12.92 ± 14.07*	.004
Pleural fluid LDH/Blood LDH	11.93 ± 46.14	5.89 ± 14.52	5.17 ± 12.18		102.81 ± 140.34*	2.17 ± 2.36	0.41 ± 0.44	<.001
Pleural protein/blood protein	0.63 ± 0.20	0.71 ± 0.11	0.67 ± 0.13		0.64 ± 0.24	0.68 ± 0.11	0.34 ± 0.26*	<0.001

Notes: TBPE: tuberculous pleural effusion; MPE: malignant pleural effusion; PPE: parapneumonic effusion; ADA: adenosine deaminase; LDH: lactate dehydrogenase; CRP: C-reactive protein. The bold values meant that compared with TBPE patients, other types of pleural effusion patients in age, Mycobacterium tuberculosis DNA detection, ADA level, total protein, glucose, LDH levels, CRP, T-SPOT.TB A , T-SPOT.TB B and pleural fluid LDH/blood LDH, pleural protein/blood protein had significant differences (p < 0.05).

*p values less than 0.05 in comparison with TB group.

Table 2. Diagnostic performance of pleural fluid Mycobacterium tuberculosis DNA detection and ADA for TBPE.

	Mycobacterium tuberculosis DNA detection	ADA
Sensitivity (95%CI)	33.3% (17.9–52.9%)	50% (31.7–68.3%)
Specificity (95%CI)	100% (90.6–100%)	78.7% (63.9–88.8%)
PPV (95%CI)	100% (65.5–100%)	60% (38.9–78.2%)
NPV (95%CI)	70.1% (57.6–80.4%)	71.1% (56.7–82.4%)
PLR (95%CI)	NaN	2.35 (1.22-4.53)
NLR (95%CI)	0.667 (0.518-0.859)	0.635 (0.439-0.919)
Youden index	0.333	0.287

Notes: PPV: positive predictive value; NPV: negative predictive value; PLR: positive likelihood ration; NLR: negative likelihood ration; NaN: the conclusion could not be performed because the values entered include one or more instances of zero.

Table 3. The comparison of baseline characteristics between pleural TB DNA positive and negative tuberculous pleural effusion.

Characteristics	Mycobacterium tuberculosis DNA detection		p Values
	Negative (n = 20)	Positive (n = 10)
Demographic characteristics
Age (years)	41.35 ± 19.67	43.30 ± 24.81	.816
Gender			.584
male	14 (70%)	6 (60%)
female	6 (30%)	4 (40%)
Pleural fluid analysis
ADA (U/L)	36.04 ± 13.77	89.31 ± 76.36	.005
ADA classification			.121
ADA ≥ 40	8 (40%)	7 (70%)
ADA < 40	12 (60%)	3 (30%)
Total protein (g/L)	49.82 ± 8.86	49.70 ± 11.92	.976
Chlorine (mmol/L)	104.53 ± 2.43	119.71 ± 45.40	.140
Glucose (mmol/L)	4.40 ± 2.06	3.54 ± 2.60	.331
LDH (U/L)	445.45 ± 229.98	3068.64 ± 5788.31	.049
LDH distribution			.037
LDH ≥ 500 (U/L)	6 (30%)	7 (70%)
LDH < 500 (U/L)	14 (70%)	3 (30%)
Blood detection
LDH (U/L)	215.50 ± 69.43	229.89 ± 62.46	.585
Total protein (g/L)	70.61 ± 5.08	67.70 ± 10.92	.324
Lymphocyte (×10^9/L)	1.02 ± 0.48	0.95 ± 0.48	.716
CRP (mg/L)	34.92 ± 31.26	59.12 ± 51.01	.124
T-SPOT.TB A	30.25 ± 22.05	30.44 ± 23.61	.983
T-SPOT.TB B	31.55 ± 25.68	25.22 ± 25.47	.543
Pleural fluid LDH/Blood LDH	2.27 ± 1.43	13.14 ± 26.16	.070
Pleural protein/blood protein	0.71 ± 0.13	0.73 ± 0.07	.656

Notes: TBPE: tuberculous pleural effusion; MPE: malignant pleural effusion; PPE: parapneumonic effusion; ADA: adenosine deaminase; LDH: lactate dehydrogenase; CRP: C-reactive protein. The bold values meant that TBPE patients with positive M. tuberculosis DNA detection showed significantly higher pleural fluid ADA and LDH levels, the results might reveal that pleural fluid ADA and LDH might help the diagnostic accuracy of M. tuberculosis DNA detection for TBPE.

Table 4. The comparison of baseline characteristics between pleural fluid ADA positive and negative tuberculous pleural effusion.

Characteristics	Pleural fluid ADA detection		p Values
	Negative (n = 15)	Positive (n = 15)
Demographic characteristics
Age (years)	46.67 ± 19.20	37.33 ± 22.52	.232
Gender			.439
male	9 (60%)	11 (73.3%)
female	6 (40%)	4 (26.7%)
Pleural fluid analysis
ADA (U/L)	28.06 ± 11.52	79.53 ± 61.69	.004
Mycobacterium tuberculosis DNA detection			.121
positive	3 (20%)	7 (46.7%)
negative	12 (80%)	8 (53.3%)
Total protein (g/L)	46.72 ± 8.05	52.83 ± 10.63	.087
Chlorine (mmol/L)	104.99 ± 3.24	114.87 ± 37.24	.349
Glucose (mmol/L)	4.99 ± 2.02	3.24 ± 2.20	.031
LDH (U/L)	406.09 ± 227.28	2233.60 ± 4800.66	.152
LDH (U/L)			.065
LDH ≥ 500 (U/L)	4 (26.7%)	9 (60%)
LDH < 500 (U/L)	11 (73.3%)	6 (40%)
Blood detection
LDH (U/L)	199.15 ± 72.21	241.44 ± 54.55	.081
Total protein (g/L)	68.95 ± 6.65	70.33 ± 8.39	.622
Lymphocyte (×10^9/L)	1.12 ± 0.49	0.86 ± 0.43	.131
CRP (mg/L)	37.39 ± 37.01	49.56 ± 43.50	.423
T-SPOT.TB A	31.14 ± 20.92	29.53 ± 23.88	.849
T-SPOT.TB B	27.78 ± 27.34	31.27 ± 24.15	.719
Pleural fluid LDH/Blood LDH	2.23 ± 1.42	9.55 ± 21.63	.202
Pleural protein/blood protein	0.68 ± 0.12	0.75 ± 0.09	.092

Notes: TBPE: tuberculous pleural effusion; MPE: malignant pleural effusion; PPE: parapneumonic effusion; ADA: adenosine deaminase; LDH: lactate dehydrogenase; CRP: C-reactive protein. The bold values meant that TBPE patients with positive pleural fluid ADA detection indicated the significantly higher pleural fluid ADA levle and lower pleural fluid glucose level than those with negative pleural fluid ADA detection.

Table 5. The diagnostic significance of pleural fluid Mycobacterium tuberculosis DNA detection and ADA for TBPE in PE cases with LDH more than 500 (U/L).

	Mycobacterium tuberculosis DNA detection	ADA
Sensitivity (95%CI)	53.8% (26.1–79.6%)	69.2% (38.9–89.6%)
Specificity (95%CI)	100% (78.1–100%)	50% (26.8–73.2%)
PPV (95%CI)	100% (56.1–100%)	50% (26.8–73.2%)
NPV (95%CI)	75% (52.9–89.4%)	69.2% (38.9–89.6%)
PLR (95%CI)	NaN	1.384 (0.770–2.490)
NLR (95%CI)	0.461 (0.257–0.830)	0.615 (0.244–1.55)
Youden index	0.538	0.192

Notes: PPV: positive predictive value; NPV: negative predictive value; PLR: positive likelihood ration; NLR: negative likelihood ration; NaN: the conclusion could not be performed because the values entered include one or more instances of zero.

Figure 1. The diagnostic value of blood T-SPOT.TB A + B/lymphocyte for TBPE. The AUC value was 0.766 (95%CI: 0.655–0.877), revealing that the ratio of blood T-SPOT.TB A + B to lymphocyte could distinguish TBPE from other types of PE.

Table 6. Diagnostic performance of T-SPOT.TB a + B/lymphocyte for tuberculous pleural effusion.

	T-SPOT.TB A + B/lymphocyte
Sensitivity (95%CI)	83.3% (65.5–93.7%)
Specificity (95%CI)	66.0% (50.6–78.7%)
PPV (95%CI)	61.0% (44.5–75.4%)
NPV (95%CI)	86.1% (69.7–94.8%)
PLR (95%CI)	2.448 (1.594–3.759)
NLR (95%CI)	0.253 (0.111–0.575)
Youden index	0.493

Notes: PPV: positive predictive value; NPV: negative predictive value; PLR: positive likelihood ration; NLR: negative likelihood ration; NaN: the conclusion could not be performed because the values entered include one or more instances of zero.