Thirty-seven RCTs (n=1622 participants) were included in the review, of which 26 were unconfounded comparing colloids with crystalloids (n=1622 participants). Seven trials were in trauma patients (n=661 participants), 12 in surgery patients (n=366 participants), four in burns patients (n=416 participants), and three in other patients (n=179 participants).
The eleven confounded trials included ten trials comparing colloid in hypertonic crystalloid with isotonic crystalloid (n=1422 participants) and one trial comparing colloid in isotonic crystalloid with hypertonic crystalloid (n=38 participants). Only the results for the 26 unconfounded studies were presented in this article the remaining studies were described on the BMJ website (http://www.bmj.com/content/316/7136/961).
Only the results of the 26 unconfounded studies were presented (see http://www.bmj.com/content/316/7136/961 for further details of the remaining confounded trials).
Risk of death:
Trauma patients (n=6 studies): RR=1.30 (95% CI: 0.95, 1.77), chi-square=1.68 (df=4).
Surgery patients (n=7 studies): RR=0.55 (95% CI: 0.18, 1.65), chi-square=1.75 (df=5).
Burns patients (n=4 studies): RR=1.21 (95% CI: 0.88, 1.66), chi-square=4.63 (df=3).
Other patients (n=2 studies): RR=1.08 (95% CI: 0.73, 1.61), chi-square=1.48 (df=1).
All patients (n=19 studies): RR=1.19 (95% CI: 0.98, 1.45), chi-square=11.67 (df=16).
Only trials with adequate concealment of allocation (n=4 studies): RR=1.29 (95% CI: 0.94, 1.77).
The regression approach to funnel plot asymmetry yielded an intercept of 0.006 and P=0.308, indicating no statistical evidence for publication bias.
Quality of the studies:
Only four of the 26 unconfounded RCTs were classed as having adequate allocation concealment (i.e. a score of 3 points). Six RCTs only scored one point for allocation concealment and the remaining 16 trials scored two points.