Limitations and potential misinterpretation of the National Disease and Therapeutic Index

This paper seeks to clarify the use and limitations of the IMS National Disease and Therapeutic Index database, which is frequently used by scholars and courts to provide insights into pharmaceutical markets. Specifically, the paper aims to discuss appropriate and inappropriate uses of the data and details the limitations as a means of drawing generalizable conclusions.

The paper takes the form of a literature review and critical evaluation of data and its uses.

The IMS NDTI can provide useful insights into pharmaceutical markets, and also provide indications of potential trends or behaviors, but cannot be relied on for conclusive evidence of such phenomena in the marketplace. The NDTI has limitations that result from sampling and design issues, as well as the specific method by which the data are collected and coded. Although IMS is clear and forthright in addressing these limitations, many researchers have apparently chosen not to heed these cautions and have drawn unsupportable conclusions from NDTI data.

The implications of drawing inappropriate conclusions from the NDTI database can range from the development of a crucial misunderstanding of the market by pharmaceutical marketers, the establishment of erroneous theories or assumptions into the literature or even the miscarriage of justice when the data are used as the basis for a legal judgment or claim. Users must be cautious when drawing any conclusions from these data.