Additional steps were taken to complement electronic database searches: First, the references given in the empirical evidence section of the HTA report of Song et al [1] were checked for relevance.
Titles were screened and abstracts were checked for relevance from 132 articles.
In total, 7153 abstracts were checked for relevance, following which 693 full papers were examined.
The titles and abstracts were checked for relevance to the evaluation review.
Documents identified by the search were checked for relevance by one reviewer (JgS).
Reference lists were checked for additional publications, which in turn were checked for relevance using the same criteria.
Initially, titles and abstracts of identified articles were checked for relevance by two reviewers (RB and PT).
Full-text versions of all shortlisted studies were checked for relevance by two researchers, with guidance from medical experts.
Primarily, the hyperlinks provided by the search engines were checked for relevance and categorised into 'relevant', 'semirelevant', and 'nonrelevant' according to Su et al (1998).
After development by five authors (JH, CJ, MT, CH and JWLC) the survey was checked for relevance and omissions by authors in all countries, pilot tested by 30 primary care clinicians in the UK and adjusted accordingly.
