Pleural effusion: chylous effusions were more likely if pleural fluid is milky or triglyceride levels were raised.

Clinical bottom line (level 4)

  1. Chylous pleural effusions occurred in around a quarter of patients with pleural effusions - over half were due to lymphoma.
  2. If the pleural fluid appears milky, this made a chylous effusion much more likely (LR+24) . Any other appearance made a chylous effusion less likely but could not exclude it (LR-0.54) .
  3. Triglyceride levels 1.0 mmol/l or more in pleural fluid made a chylous effusion more likely (LR+13) . Levels of < 1.0 mmol/l made a chylous effusion much less likely (LR-0.14) .
  4. Cholesterol levels were not very helpful.
Staats et al: Mayo Clinical Protocol 1980; 55: 700-704
Expires October 2003

The study

Setting: university hospital, USA

141 patients (aged ?, ?% male) pleural effusion

Independent unblinded reference standard, applied in all patients from a consecutive appropriate spectrum.
Reference standard:
  • chylomicrons in pleural fluid
Diagnostic test:
  • appearance of fluid: chylous (milky or creamy)
  • fluid triglyceride and cholesterol levels

The evidence

pre-test probability of chylous: 27%, (95% CI: 20% to 34%)

differential diagnosis number of patients prevalence
(95% CI)
final diagnosis (chylous effusions): lymphoma 20 53%
(37% to 69%)
post-operative or traumatic 9 24%
(10% to 37%)
idiopathic 5 13%
(2.4% to 24%)
carcinoma 2 5.3%
(0.0% to 12%)
other (cirrhosis or pleuritis) 2 5.3%
(0.0% to 12%)


diagnostic test chylous not chylous LR+
(95% CI)		 post-test probability LR-
(95% CI)		 post-test probability
chylous appearance 18 2 24
(6.0 to 100) 		90% 0.54
(0.40 to 0.73) 		17%
triglyceride 1.0 mmol/l or more 33 7 13
(6.2 to 26) 		83% 0.14
(0.062 to 0.32) 		5%
cholesterol 2.0 mmol/l or more 27 43 1.7
(1.3 to 2.3) 		39% 0.50
(0.29 to 0.84) 		15%
total 38 103

Comments

  1. This is a very high proportion of chylous effusions.
  2. Cut-off values chosen by assessor.
  3. No details on how final diagnoses were reached.

Citation

  1. Staats BA, Ellefson RD, Budahn LL, et al: the lipoprotein profile of chylous and non chylous pleural effusions. Mayo Clinical Protocol 1980; 55: 700-704
Search Terms: reference from Pleural effusion chapter in 'Quick Consult Manual to Evidence-based Medicine': publd. Lippincott-Raven, 1997
Contributor: Chris Ball and Clare Wotton, October 2000
Reviewer:

Clinical Question.
Patient pleural effusion
Intervention or Exposure appearance of fluid, triglyceride and cholesterol levels
Outcome chylous effusions