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Centre for Evidence-
Based Medicine

Critically ill patients - Crystalloids are safer than colloids

Purchasing Bottom Line

Use of colloids was associated with an increase of absolute risk of mortality of 4%.


Schierhout G, Roberts I, Alderson P. Colloids compared to crystalloids in fluid resuscitation of critically ill patients (Cochrane Review). In: The Cochrane Library, 4, 1998. Oxford: Update Software.

Purchasing Question

In routine resuscitation of critically ill patients, are colloids or crystalloids more effective?

Search Terms

"colloids" AND "crystalloids" and "resuscitation" in The Cochrane Library, MEDLINE

The Study

Systematic review of 37 RCTs with a total of 1622 patients. Mortality data derived from 19 of the 37 RCTs with 1315 patients.

The Evidence

AR(colloids) AR(crystalloids) RR
ARR NNH with colloids (or treat with crystalloids to avoid death)
Total deaths (all patients) 168/685
= 0.25
= 0.19
1.31 0.058 17
Deaths from trauma 82/335
= 0.24
= 0.15
1.60 0.09 11
Deaths from surgery* 3/105
= 0.029
= 0.07
0.41 -0.04 25 (NNH with crystalloids)
Deaths from burns 60/207
= 0.29
= 0.24
1.20 0.05 20

The evidence (from weighted data in relative risk table and results section)

Total deaths (all patients) 1.19 (0.98-1.45) 0.04 (0.0-0.08) 25 (13 to infinity)


  1. *On first glance, it appears that surgical patients do better with colloids, but it should be noted that this result is not significant, and based on a small number of patients (117) and deaths (9).
  2. It might be noted that the overall relative risk of mortality from colloids vs. crystalloids is not statistically significant (the confidence intervals cross the 1.0 line). However, this probably does not invalidate the main message from the study that crystalloids are at least as safe if not safer than colloids, and an awful lot cheaper for general use in Accident and Emergency!

Appraised By

Anna Donald and Sam Vincent March 1999.

Expiry Date

March 2001