The best known source of medical literature is the "PubMed" service of the US National Library of Medicine. Searching PubMed, however, can be something of a task. With a topic as restricted as "chilblains" (pernio) it's not too hard to keep up with the literature. But, when the subject is as diverse as palliative care just searching "palliative care" won't really do the trick. It looks like a lot, and it is, but, unfortunately it does not necessarily capture all of the other elements of the practice of palliative care.

"Terminal care" is a subject intimately linked with the practice of "palliative care" and you would imagine that a search for one would share a significant number of similar results when you searched for the other. Try these searches and see "palliative care", "terminal care". However, when a search is constructed (using AND) to show how many citations these searches share the result is "interesting". They actually share relatively few citations. This is a result of the process of indexing; more of which later, a process that identifies themes in documents. Unless "palliative care" is part of the document's explicit content it will not be indexed under "palliative care" regardless of how closely the searcher associates the two themes.

These difficulties have not gone unnoticed; hence the initial effort of St B's to provide a tool to retrieve some of this material. However, unknown to St B's when we started looking into this, some smart people in Australia's nether regions (South Australia) were doing the same thing in a highly systematic fashion.

CareSearch, an extensive source of online palliative care resources, had started by predefining a collection of searches on topics relevant to palliative care such as anorexia, nausea and dyspnoea. Unfortunately, as you can see, if you have tried the searches, the number of citations returned is huge (over 40,000 for dyspnoea) and it is difficult to know how to manage them. These sample searches offer the most extreme examples and other, more restrictive, searches are available at CareSearch, such as retrieving only free text available articles; this, however, can be done directly in "PubMed" and does not need any preparation in advance.

In an attempt to capture relevant literature, St B's devised a search term which retrieved an unknown portion of that literature from PubMed. St B's first attempt at deriving a "general palliative care" search term has, as it has turned out, not been as effective as we had at first hoped. Over at CareSearch, however, some hard work has been going on generating a general palliative care search term, the effectiveness of which has actually been measured. Links to their expanded search term and inital publication have been posted on their web site. June 2007 saw publication of further expansion of this work. However, the construction of their search term using "limits", such as [mh] (MeSH heading) and [tiab] (title and abstract), create difficulties for frequent updates using that term, due to the time delay in indexing the PubMed database. Until an entry is indexed, MeSH headings and other "limits" dependent on indexing, are not effective; indexing may take several weeks.

Run these two searches which use the CareSearch term, restricted to the previous 30 days, with and without the "limits".

CareSearch -with [mh] and [tiab] and then CareSearch - no limits

A substantial difference. In fact for both searches the limiters for "death" [mh:noexp] have been retained, otherwise they search in places we do not wish to look.

St B's original term was substantially less comprehensive in retrieving citations than that derived by CareSearch. However, when the citations recovered by the two terms were compared, it was noted that St B's search term recovered a modest, but significant, body of literature not retrieved by the CareSearch term. As a result St B's has combined and simplified the search terms, and started posting its regular updates using the combined term in the middle of July 2007.

Here it is:

palliat* OR terminal care OR terminally ill OR hospice* OR "end of life" OR advance directives OR advance care planning OR withholding treatment OR bereavement OR grief OR attitude to death OR life support care OR death[mh:noexp]

You can give it a twirl here to get the last 30 days worth.

However, St B's search suffers from the same difficulty with "death[mh:noexp]" as does CareSearch. Without the restraints imposed by [mh:noexp] the returned set of citations would be valueless. Try these and see "death" and then "death[mh:noexp]". The problem is that "death[mh:noexp]" as a search term will have very little impact on the citations returned in these regular, frequent updates because it has not been indexed. Nevertheless, St B's is continuing with its expanded search term and will decide what to do about the "death" problem at a later date.

St B's does not claim that this search term will recover every citation relevant to the practice of palliative care, indeed that is unlikely ever to be possible due to the diverse nature of palliative care, but it does cover what St B's considers to be major topics pertinent to the practice of palliative "care" ; that is, it includes subjects other than the medical topics of pain management and symptom control.

Although the best way of dealing with the problem is to learn a bit about how PubMed works, getting there is a bit of a bore unless you are a burning the midnight oil sort of person - or really short of something else to do. Because St Basillisa's is that sort of an entity it has preconfigured some searches which may be useful to you.

Three groups of searches have been prepared.

1. A search of the full PubMed database to retrieve articles relevant to palliative care using the search term discussed above.

2. Searches to raise "contents like" pages of journals identified as being "palliative care" specific.

3. Searches of a group of general medical journals to return citations relevant to palliative care using the general search term.

4. A set of searches using the general palliative care search term updated on a weekly basis has been set up. This allows incremental updating of your palliative care literature collection.

To prevent being overwhelmed by thousands of citations the searches in categories 1, 2 and 3 are restricted to time the bands 30, 60, 90 days since entry, "entrez", into PubMed.