After the last post (New: Controlled Trials in Trip) we got the following comment:

Will you make the information about the PubMed filters for your controlled trials available so we can get an idea how comprehensive your database is. Will you also compare your results with those listed in the central database of controlled trials in the cochrane library? 

This seems entirely reasonable, so the first part of the comment, the filters:

Julie Glanville suggested 4 different filters, all with different sensitivity and specificity):

  1. (randomized controlled trial[Publication Type]) OR ((randomized[Title/Abstract] OR randomised[Title/Abstract] OR placebo*[ti]) and (controlled[Title/Abstract] OR trial[Title/Abstract]))
  2. (randomized controlled trial[Publication Type]) OR ((randomized[Title/Abstract] OR randomised[Title/Abstract] OR placebo*[tiab]) and (controlled[Title/Abstract] OR trial[Title/Abstract]))
  3. (randomized controlled trial[Publication Type]) OR ((randomized[TI] OR randomised[TI] OR placebo*[ti]) OR (controlled[TI] OR trial[Ti]))
  4. (randomized controlled trial[Publication Type]) OR ((randomized[Title/Abstract] OR randomised[Title/Abstract] OR placebo*[tiab]) OR (controlled[Title/Abstract] OR trial[Title/Abstract]))

I tried these all out in PubMed and got the following numbers of identified trials for each filter:

  1. 419575
  2. 434984
  3. 438900
  4. 921118

The 4th, being so different from the first three seemed easy to ignore while the other three, all being within 10% was reassuring.  So, I decided to go for number 3.  Testing revealed some false positives but nothing too scary!

With regard the second part of the comment, comparing the results with CENTRAL.  I’d be delighted for someone else to, but we don’t have the resource or the knowledge to do so!

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