Letters

Competing interests and controversy about third generation oral contraceptives

BMJ 2000; 320 doi: http://dx.doi.org/10.1136/bmj.320.7231.381/a (Published 05 February 2000) Cite this as: BMJ 2000;320:381

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BMJ readers should know whose words they read

  1. Jan P Vandenbroucke, professor, department of clinical epidemiology ([email protected]),
  2. Frans M Helmerhorst, lecturer, department of obstetrics, gynaecology, and reproductive medicine,
  3. Frits R Rosendaal, professor, thrombosis and haemostasis research centre
  1. Leiden University Medical Centre, PO Box 9600, 2300 RC Leiden, Netherlands
  2. BMJ
  3. Royal College of General Practitioners Centre for Primary Care Research and Epidemiology, Department of General Practice and Primary Care, University of Aberdeen, Foresterhill Health Centre, Aberdeen AB25 2AY

    EDITOR—The influence of competing interests arising from funding by the pharmaceutical industry is worrying in the controversy about third generation oral contraceptives.1 At the end of 1998 three major studies without sponsoring from the industry found a higher risk of venous thrombosis for third generation contraceptives, unlike three sponsored studies.2 To date, of nine studies without sponsoring, one study found no difference and the other eight found relative risks from 1.5 to 4.0 (summary relative risk 2.4); four sponsored studies found relative risks between 0.8 and 1.5 (summary relative risk 1.1) (references available on the BMJ's website, www.bmj.com). The sponsored study with a relative risk of 1.5 has been reanalysed several times, yielding lower relative risks; after this failed to convince,3 a new reanalysis was sponsored by another company.4

    In 1995 four studies found the same risk. That evidence was sufficient for public health action since equally reliable pills were available. For at least one company the third generation pill secured more than half its revenue. The companies proclaimed that with almost total certainty everything was the result of bias and confounding. Even for a sceptic at the time, that was an unreasonable position: all four studies were reasonably executed and had withstood criticism from the Committee on Safety of Medicines and reviewers of leading journals. Thus, the companies' position ran the …

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