Little information was given on inclusion criteria

EDITOR—Rodgers et al report a meta-analysis of 141 trials comparing general anaesthesia with neuraxial blocks.1 They conclude that their data should result in more widespread use of spinal or epidural anaesthesia. The challenge for clinicians is deciding which of their patients (if any) these results apply to, but Rodgers et al provided little information about the inclusion criteria for the trials examined. The applicability of a meta-analysis is difficult to assess when heterogeneous patient groups are combined. Also, although a spinal or epidural anaesthetic might be reasonably standard, there are many general anaesthetic agents and these may not be comparable.

Figure 1 of the meta-analysis shows that four trials contributed 31 deaths to the overall mortality difference of 41.2^–5 In those four studies the mortality from general anaesthesia ranged from 8% to 27%, compared with 3.1% for all trials combined.

We wonder whether any information was collated on antithrombosis prophylaxis. In 2001 most patients at risk of venous thrombosis having a general anaesthetic will receive prophylaxis including anticoagulation drugs at low doses. Of the four trials referred to above, three are over 15 years old, and at least one specifically excluded patients receiving low dose anticoagulation.3

Figure 2 of the meta-analysis indicates an apparent benefit of neuraxial block in orthopaedic patients.1 Mortality after vascular, urological, and general surgery showed no significant difference. We therefore question the conclusion …