Low molecular weight heparins represent a promising class of drugs, with important advantages over unfractionated heparin in terms of convenience and time saved to patients and staff. However, the use of a composite outcome measure in trials of both drugs makes it impossible to draw a definite conclusion on the benefits of treatment, as the uncertainty around individual outcomes is consistent with no effect or even harm. The committee noted that dalteparin use was associated with an increased number of deaths in the FRIC trial, although the number of cases was small, and that minor haemorrhage rates were increased in the ESSENCE trial of enoxaparin. It was not clear whether the reduction in invasive coronary procedures (PTCA and CABG) would in practice result in realisable savings in the UK, given the small numbers involved in the trials and difficulties in applying results from overseas.
The evidence in this area is evolving rapidly and the Committee asked for it to be kept under review.