“Pharmacological Action” in PubMed has no True Equivalent in OVID MEDLINE

11 01 2012

Searching for EMBASE Subject Headings (the EMBASE index terms) for drugs is relatively straight forward in EMBASE.

When you want to search for aromatase inhibitors you first search for the Subject Heading mapping to aromatase inhibitors (aromatase inhibitor). Next you explode aromatase inhibitor/ if you are interested in all its narrower terms. If not, you search both for the general term aromatase inhibitor and those specific narrower terms you want to include.
Exploding aromatase inhibitor (exp aromatase inhibitor/) yields 15938 results. That is approximately twice what you get by searching aromatase inhibitor/ alone (not exploded). This yields 7434 hits.

It is different in MEDLINE. If you search for aromatase inhibitors in the MeSH database you get two suggestions.

The first index term “Aromatase Inhibitors” is a Mesh. It has no narrower terms.
Drug-Mesh are generally not arranged by working mechanism, but by chemical structure/type of compound. That is often confusing. Spironolactone for instance belongs to the MeSH Lactones (and Pregnenes) not to the MeSH Aldosterone Antagonists or Androgen Antagonist. Most Clinicians want to search for a group of compounds with the same mechanism of action, not the same biochemical family

The second term “Aromatase Inhibitors” [Pharmacological Action]  however does stand for the working mechanism. It does have narrower terms, including 2 MeSH terms (highlighted) and various substance names, also called Supplementary Concepts. 

For complete results you have to search for both MeSH and Pharmacological action: “Aromatase Inhibitors”[Mesh] yields 3930 records, whereas (“Aromatase Inhibitors”[Mesh]) OR “Aromatase Inhibitors” [Pharmacological Action] yields 6045. That is a lot more.

I usually don’t search PubMed, but OVID MEDLINE.

I know that Pharmacological Action-subheadings are important, so I tried to find the equivalent in OVID .

I found the MeSH Aromatase Inhibitors, but -unlike PubMed- OVID showed only two narrower Drug Terms (called Non-MeSH here versus MeSH in PubMed).

I found that odd.

I reasoned “Pharmacological action” might perhaps be combined with the MESH in OVID MEDLINE. This was later confirmed by Melissa Rethlefsen (see Twitter discussion below)

In Ovid MEDLINE I got 3937 hits with Aromatase Inhibitors/ and 5219 with exp Aromatase Inhibitors/ (thus including aminogluthemide or Fadrozole)

At this point I checked PubMed (shown above). Here I found  that “Aromatase Inhibitors”[Mesh] OR “Aromatase Inhibitors” [Pharmacological Action] yielded 6045 hits in PubMed, against 5219 in OVID MEDLINE for exp Aromatase Inhibitors/

The specific aromatase inhibitors Aminogluthemide/and Fadrozole/ [set 60] accounted fully for the difference  between exploded [set 59] and non-exploded Aromatase Inhibitors[set 58].

But what explained the gap of approximately 800 records between “Aromatase Inhibitors”[Mesh] OR “Aromatase Inhibitors”[Pharmacological Action]* in PubMed and exp aromatase inhibitors/ in OVID MEDLINE?

Could it be the substance names, mentioned under “Aromatase Inhibitors”[Pharmacological Action], I wondered?

Thus I added all the individual substance names in OVID MEDLINE (code= .rn.). See search set 61 below.

Indeed these accounted fully for the difference (set 62= 59 or 61 : the total number of hits in PubMed is similar)

It obviously is a mistake of OVID MEDLINE and I will inform them.

For the meanwhile, take care to add the individual substance names when you search for drug terms that have a pharmacological action-equivalent in PubMed. The substance names are not automatically searched when exploding the MeSH-term in OVID MEDLINE.

——–

For more info on Pharmacological action, see: http://www.nlm.nih.gov/bsd/disted/mesh/paterms.html

Twitter Discussion between me and Melissa Rethlefsen about the discrepancy between PubMed and OVID MEDLINE (again showing how helpful Twitter can be for immediate discussions and exchange of thoughts)

[read from bottom to top]


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