DATA ON FILE CITED IN PHARMACEUTICAL ADVERTISEMENTS: WHAT ARE THEY?

Andrew Herxheimer
UK Cochrane Centre, 9 Park Crescent, London N3 2NL, UK

Objective: To estimate the frequency of citations of "data on file" in drug advertisements, to survey how companies respond to requests for them, and to ascertain the nature of the data.

Design: All drug ads in 9 consecutive issues of Hospital Doctor and 5 issues of Prescriber (aimed at UK General Practitioners) published in the last quarter of 1996 were surveyed. In the first week of 1997 all companies citing "data on file" or other unpublished material in any of these ads were asked by fax for copies. Eleven further ads from recent issues of other journals were investigated likewise.

Results: The 14 issues contained 95 different full drug ads, each being repeated 4 times on average. About half cited one reference or more. Twenty-five (26%) referred to unpublished material, mostly "data on file." Thirty-eight different ads from 28 companies were investigated; 25 of them cited on data on file as a reference, 10 ads cited 2 data on file references, 3 ads had 3 data on file references. Eighteen of the ads referred to unidentified documents, the others gave a code number or indicated the nature of the document. One ad cited an unpublished paper by author and title as "submitted for publication." Initial responses to 19 of the 38 requests were received within 10 days. Much of the material was incomplete, consisting of abstracts or summaries not permitting critical evaluation; further correspondence was often needed. Three companies' material was marked "confidential."

Conclusions: "Data on file" are used to justify crucial promotional claims, but the documentation is often of low quality. Many claims thus seem inadequately supported. Standards and remedies are needed.

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