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CMAJ • March 18, 2003; 168 (6)
© 2003 Canadian Medical Association or its licensors

Letters
Correspondance

Mandatory pharmacovigilance

Walter P. Maksymowych

Associate Professor and Consultant Rheumatologist, University of Alberta, Edmonton, Alta.

A recent CMAJ editorial1 commented on the lack of objective, user-friendly information from Health Canada and the pharmaceutical industry regarding the use and effectiveness of new therapies. However, one cannot help but perceive an element of hypocrisy on the part of CMAJ.

Since July 1994, CMAJ has provided a means of distribution for Health Canada's Canadian Adverse Reaction Newsletter (initially as part of the journal itself and now as an accompanying publication) without any editorial critique of the information presented there. Such critique is warranted for several reasons. In particular, the newsletter publishes information with medicolegal implications for appropriate medical practice.

However, many physicians have serious concerns about Health Canada's continuing reliance on a highly flawed approach to postapproval surveillance and the department's interpretation of the resulting data. A case in point: the October issue of the newsletter described potentially severe adverse reactions associated with leflunomide,2 but when all patients exposed to the drug have been monitored, the rate of adverse events reported for leflunomide has been lower than for methotrexate or other commonly used disease-modifying antirheumatic drugs for rheumatoid arthritis.3 Crude mortality rates were also lower for the patients who received leflunomide. Similar data attesting to the relative safety of leflunomide compared with methotrexate have been presented in another large study monitoring all patients exposed to leflunomide.4

In addition to revealing errors of ascertainment, these data highlight the serious limitations in attribution that may occur in surveillance programs that do not monitor exposure to the drug in question. Several countries have recognized and acted on these concerns by implementing surveillance programs that do monitor exposure (e.g., the UK National Institute of Clinical Excellence for Surveillance of Biologics). Meanwhile, as CMAJ's editorialists indicated, Health Canada is only hesitantly "grasping the nettle" in addressing this issue. It is therefore all the more essential that the data it presents in its newsletter be subject to the same degree of scrutiny and peer review as any other data submitted to CMAJ.

Walter P. Maksymowych Associate Professor and Consultant Rheumatologist University of Alberta Edmonton, Alta.

Footnotes

Competing interests: Dr. Maksymowych has received speaker fees from Merck and educational grants from Aventis.


References

  1. Drug marketing: Unsafe at any dose? [editorial]. CMAJ 2002;167(9):981.[Free Full Text]
  2. Leflunomide (Arava): hematologic, hepatic and respiratory reactions. Can Adverse React Newsl 2002;12(4):2-3.
  3. Emery P, Cannon G, Holden W, Strand V, Schiff M. Results from a cohort of over 40,000 rheumatoid arthritis patients: adverse event profiles of leflunomide, methotrexate and other disease-modifying antirheumatic drugs [abstract]. Ann Rheum Dis 2002;61(Suppl 1):42. [Abstract/Free Full Text]
  4. Wolfe F. Low rates of serious liver toxicity to leflunomide and methotrexate: a longitudinal surveillance study of 14,997 leflunomide and methotrexate exposures in RA [abstract]. Arthritis Rheum 2002;46(Suppl):S375.




This Article
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