Recently, we have learned that PubMed matching is not quite as exact as we previously thought. After corresponding with the team at NLM, we want to share some information about cases where PubMed matching will link even though the information in a reference is not exactly the same as the PubMed record. The following information comes directly from NLM:

"We do allow a little fuzziness or forgiveness for the volume and issue indexes because unfortunately these data are frequently messy. Here are a few examples:

"If the citation only includes a volume and no issue the volume is also indexed in issue.

"If the citation only includes an issue and no volume the issue is indexed in the volume field as well.

"Citations with volume with suppl, part, edition, etc. include an index to the single digit as well.

"Citations with an issue with parts but no volume, the issue is also indexed in volume."

What this means is that in some cases, even if information isn't provided correctly, the reference will still link on PubMed. For example, in the following reference:

Banit DM, Kaufer H, Hartford JM. Intraoperative frozen section analysis in revision total joint arthroplasty. Clin Orthop Relat Res. 2002; (401):230-238

401 is the issue number, not the volume number (Clin Orthop Relat Res uses only issue numbers and does not assign volume numbers). Note that in the latest eXtyles^® code, this reference will correctly parse, treating the 401 as an issue number.

However, if this reference were submitted by the author as:

Banit DM, Kaufer H, Hartford JM. Intraoperative frozen section analysis in revision total joint arthroplasty. Clin Orthop Relat Res. 2002; 401:230-238

eXtyles treats 401 as the volume number. In this situation, given the rules above, PubMed will still create the link.

A few other examples may be helpful. For example, PubMed will link the following reference, even though the correct date is "1998-1999", not "1998":

Marmor MF, Zrenner E. Standard for clinical electroretinography (1999 update): International Society for Clinical Electrophysiology of Vision. Doc Ophthalmol. 1998;97:143-156.

In fact, PubMed will link the reference in either case. And in one more example, which illustrates how the system is not as flexible as one might expect, PubMed will link:

Lieberman JR, Daluiski A, Stevenson S, et al: The effect of regional gene therapy with bone morphogenetic protein-2-producing bone-marrow cells on repair of segmental femoral defects in rats. J Bone Joint Surg 1999;81-A:905-917.

where "81-A" is the correct volume number; PubMed will also link "81". However, PubMed does not link "81A" where the hyphen is not included.

So what does this all mean? If your goal is to have references that are accurate enough to link, then eXtyles PubMed Checking should ensure that references will link correctly when they appear online. However, you should be aware that in some cases PubMed validation by eXtyles does not ensure that the reference exactly matches the original printed article.

Please feel free to contact Inera if you have questions.