Impact of US policy on information retrieval

Summary

• In Germany, information retrieval relies heavily on freely accessible medical information services from the United States. Currently, there are no comparable German, European or international alternatives that are freely accessible.
• The most important information sources currently at risk of an outage are the bibliographic database PubMed (MEDLINE) and the study registry ClinicalTrials.gov. This document is intended to provide support in the event that access to these two services is no longer possible.

• The PubMed (MEDLINE) archive would remain accessible in the event of an outage and could be searched via fee-based platforms such as MEDLINE (Ovid) or free services such as Europe PubMed Central (PMC). Any outage would only affect future data, so the resulting gap would only appear slowly, but would particularly affect the most current research.
• Currently, other freely accessible bibliographic databases or their combination cannot completely replace the content of PubMed (MEDLINE). A combination of a medical bibliographic database such as Embase (fee-based) and the Crossref data pool (e.g., via the "Lens" search interface) would be a partly fee-based and more resource-intensive approach.
• However, the main problem lies less in the basic coverage than in the retrievability of the references. The search functions, extensive metadata and search filters (e.g., "Hedges filters") for PubMed (MEDLINE), which have been developed over decades by information specialists, cannot be transferred to other platforms, or only to an insufficient extent, and therefore cannot be easily replaced.

• The ClinicalTrials.gov archive will continue to be accessible via the WHO ICTRP search portal. However, the portal’s entries are only an aggregate of the ClinicalTrials.gov entries. Information on study results and the documents stored in ClinicalTrials.gov is completely missing in the WHO registry. In a next step, further search steps would have to be taken when accessing the WHO registry (e.g., via the Internet Archive WayBack Machine) in order to identify the associated study documents.
• Future studies can be registered in national (e.g., DRKS) or international study registries (e.g., ISRCTN). The European study registry CTIS is still of great importance for drug studies and should also be opened up to voluntary registration of other study types or research questions, for example.

In Europe, the key stakeholders in the healthcare sector should ask themselves how they can counter an outage of PubMed and ClinicalTrials.gov. The following measures would be meaningful:

• Existing databases could take over the tasks of PubMed. For example, Europe PMC or the German Central Library (ZB Med) with Livivo (and potentially the Open Life Science Publication Database [OLSPub] in future), could set up the necessary infrastructure.
• The creation of an interface with professional search functions. Since most of the MEDLINE data are freely available via Crossref, an API interface could be used to create a separate interface and thus overcome the limitations of Lens described above.
• For study registries, the task is to expand and open up existing alternatives (e.g., CTIS) or support central platforms (e.g., ISRCTN).

PubMed (MEDLINE) is a bibliographic database operated by the National Library of Medicine (NLM). It includes references from the fields of medicine, biochemistry, genetics and molecular biology, pharmacology, toxicology and pharmacy. It offers free access to MEDLINE and PubMed Central (full texts), among others.

MEDLINE was developed in the 1960s and includes citations from more than 5200 scientific journals worldwide. In total, the PubMed database contains more than 38 million citations and abstracts of biomedical literature.

Alternatives to PubMed (MEDLINE)

Appendix A provides an overview of possible alternatives. The selection was based on the data pools available, the search functions and availability. These alternatives were primarily identified via https://www.searchsmart.org.

Table 1 shows the extent to which the data pools of the Embase and Crossref databases overlap with MEDLINE, based on current journal lists from these two databases.

For the purposes of this paper, IQWiG also examined which databases provide access to archives with adequate search functions. This resulted in the following recommendations (Table 2):

Crossref data can currently only be searched via so-called mega-citation indexes such as Lens or OpenAlex. However, these indexes only offer limited options for classic Boolean searches. In addition, keywords are missing, abstracts are not always available, and search functions are limited. As a result, systematic and professional searches in these indexes are not possible at the same level as in established bibliographic databases such as MEDLINE or Embase. Despite these limitations, in combination with other databases, they are currently the only way to depict the MEDLINE data pool as completely as possible.

ClinicalTrials.gov is the US registry for registering clinical trials and reporting their results. It was established by the FDA Modernization Act of 1997 and went online in 2000.

Initially, the area subject to regulation only covered the registration of studies within the FDA’s remit. However, since its establishment, the registry has also been open to the voluntary registration of other studies. As a result of further regulatory developments, the registry has expanded to become the largest and most important of its kind in the world. Over half a million studies are currently registered there. At the same time, it offers extensive search functions compared to other study registries and, in addition to detailed results, also contains other relevant documents such as study protocols and statistical analysis plans (SAPs).

Alternatives to ClinicalTrials.gov

Possible alternatives to ClinicalTrials.gov are shown in Appendix B. Registries that were primarily designed as national registries were not considered. In the event that ClinicalTrials.gov is no longer available, the following recommendations for searching study registries apply:

The next step is to look at further alternatives and practical solutions:

• IQWiG is testing the use of Crossref via Lens in practice to clarify whether completeness (in terms of recall and coverage) can also be achieved in everyday work. Import filters also need to be optimized etc.
• IQWiG is investigating whether the Internet WayBack Machine saves all the PDFs contained in ClinicalTrials.gov.

This document will be updated as new information becomes available.