In reply: Johnson's letter raises an important point about the influence of external agencies such as pharmaceutical companies in the development of clinical practice guidelines. Although our systematic review1 of 30 studies of clinician attitudes to clinical practice guidelines did not identify this issue as a major barrier, it is possible that the surveys used overlooked this concern. Conflict-of-interest statements and the source of funding for clinical practice guidelines and their development teams are not always published. In the AGREE2 questionnaire (a measurement instrument developed for clinical practice guidelines), reporting conflict of interest and source of funding is encouraged. The New Zealand Guideline Group has a policy of declaring conflicts of interest, and pharmaceutical industry representatives are not included in guideline development teams.3

Choudhry et al4 reported that 59% of guideline authors had financial relationships with companies whose drugs were considered in the guideline they authored. Although these figures are not surprising given the role of the industry in research and educational activities, they do present a challenge to guideline development teams. The New Zealand Guideline Group approach (apart from declaring conflicts of interest and not including industry representatives on guideline development teams) is to take an evidence-based strategy. This involves considering all available evidence, publishing search strategies, linking evidence tables to evidence statements and recommendations, developing the recommendations by using a "considered judgement form" (which takes into account evidence, cost, generalisability and applicability), and drawing on representatives from a broad range of stakeholders (including consumer and allied health groups). By taking such an approach, it is hoped that the influence of external agencies can be minimised.