Table 1.
Characteristics of the study population and pleural fluid
| Total Cohort (n = 83) | Transudate (n = 33) | Exudate (n = 50) | |
|---|---|---|---|
| Demographics | |||
| Age, yr | 61.0 (55.0–68.0) | 57.0 (55.0–67.5) | 62.0 (47.8–70.3) |
| Sex, male | 63 (76) | 23 (70) | 40 (80) |
| Etiology of pleural effusion | |||
| Cirrhosis* | 28 (34) | 19 (58) | 9 (18) |
| Heart failure | 8 (10) | 6 (18) | 2 (4) |
| Cancers combined* | 24 (29) | 4 (12) | 20 (40) |
| Lung cancer | 9 (11) | 1 (3) | 8 (16) |
| Nonlung cancer | 15 (18) | 3 (9) | 12 (24) |
| Pneumonia* | 11 (13) | 1 (3) | 10 (20) |
| ESRD | 5 (6) | 2 (6) | 3 (6) |
| Other | 7 (8) | 1 (3) | 6 (12) |
| Pleural fluid lab values | |||
| pH (n = 44) | 7.4 (7.3–7.5) | 7.4 (7.3–7.7) | 7.4 (7.2–7.5) |
| Glucose, g/dl (n = 58) | 117 (102–154) | 138 (110–161) | 115 (96–137) |
| RBC count (n = 77)* | 2,520 (1,000–15,188) | 1,025 (<1,000–3,300) | 3,406 (1,094–63,250) |
| WBC count (n = 77)* | 500 (200–1,708) | 197 (113–433) | 1,150 (451–2,799) |
| LDH, IU/L* | 113 (67–232) | 56 (48–86) | 191 (111–368) |
| Protein, g/dl (n = 82)* | 3.0 (<2–3.9) | <2 (<2–3.0) | 3.8 (3.0–4.4) |
| LDH ratio, pleural:serum (n = 78)* | 0.60 (0.34–1.19) | 0.32 (0.20–0.42) | 1.03 (0.61–1.74) |
| Protein ratio, pleural:serum (n = 82)* | 0.50 (0.40–0.61) | 0.38 (0.33–0.43) | 0.58 (0.51–0.67) |
| Pleural fluid ultrasound | |||
| Homogeneously anechoic | 47 (57) | 22 (67) | 25 (50) |
| Floating debris | 21 (25) | 6 (18) | 15 (30) |
| Fibrinous stranding* | 22 (27) | 4 (12) | 18 (36) |
| Loculations | 15 (18) | 3 (9) | 12 (24) |
| Pleural fluid pixel density*† | |||
| Median | 2.74 (1.23–5.94) | 2.32 (0.82–3.81) | 3.53 (1.43–8.34) |
| Mean | 5.10 (3.62–6.57) | 2.74 (1.96–3.53) | 6.65 (4.32–8.97) |
Definition of abbreviations: ESRD = end-stage renal disease; LDH = lactate dehydrogenase; RBC = red blood cell; WBC = white blood cell.
Median and interquartile range (25th–75th percentile) reported for continuous variables, with Mann-Whitney test used for P value unless otherwise noted. Count and percentage reported for categorical variables, with Fisher exact test used for P value.
*
Statistically significant difference between transudates and exudates, with a P value < 0.05.
†
Mean and 95% confidence interval reported for pleural fluid pixel density, with t test used for P value.