BMJ  2006;333:499 (2 September), doi:10.1136/bmj.333.7566.499-a

Letter

Where next for China?

Keep to the basic principles of critical appraisal

The first 150 words of the full text of this article appear below.

EDITOR—In the review by Liu et al of treatment of hyperbaric oxygen, several methodological issues need to be addressed.¹ Alternate allocation to treatment group, or methods based on patient characteristics such as date of birth, order of entry into the clinic, or day of clinic attendance are not reliably random. Such allocation sequences are predictable and reduce the guarantee that no potential subjects have been excluded by foreknowledge of the intervention.² These trials should be removed in a sensitivity analysis as well as the trials not reporting "random" in the methods section. Authors should be contacted for clarification if inadequate reporting is thought to be the problem.

Using simple randomisation methods often leads to the sample size being similar in the two groups and inadequate reporting of the baseline characteristics.³ Attempts should be made to compare the baseline characteristics of trials where allocation concealment is unclear or not . . . [Full text of this article]

Centre for Evidence-Based Medicine, Department of Primary Health Care, University of Oxford, Oxford OX3 7LF carl.heneghan@dphpc.ox.ac.uk

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Relevant Article

Clinical effectiveness of treatment with hyperbaric oxygen for neonatal hypoxic-ischaemic encephalopathy: systematic review of Chinese literature

Zulian Liu, Tengbin Xiong, and Catherine Meads
BMJ 2006 333: 374. [Abstract] [Full Text] [PDF]

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