BMJ  2003;327:162 (19 July), doi:10.1136/bmj.327.7407.162-a

Letter

Cervical cancer screening

Authors' reply

The first 150 words of the full text of this article appear below.

EDITOR—Ind and Whitley, as well as other respondents to our paper on bmj.com, refer to the issue of our split sample design.1 Many such previous studies show that monolayers are superior to conventional smears (and were used to obtain approval from the Food and Drug Administration for ThinPreps). Now some who praised this design when it favoured monolayers are discovering that it is "flawed" or "faulty" when it gives the opposite results.

Our paper shows that the main issue for monolayer evaluation is not the split sample bias (paucicellular monolayers were negligible, and the results were similar for the subgroup of women with large amounts of material remaining after monolayer preparation). It is instead the workup or verification bias, present whenever the reference test is not systematically used. This bias inflates sensitivity and favours the test with the higher rate of false positive results: the monolayer technique. . . . [Full text of this article]

Joël Coste, professor of medical statistics

Département de Biostatistique, Hôpital Cochin, Assistance Publique-Hôpitaux de Paris, Faculté de Médecine Cochin-Port Royal, Université Paris V, Paris, France coste@cochin.univ-paris5.fr

Béatrix Cochand-Priollet, assistant-professor of pathology

Service d'Anatomie et Cytologie Pathologiques, Hôpital Lariboisière, Assistance Publique-Hôpitaux de Paris, Paris

Patricia de Cremoux, assistant-professor of pharmacology

Laboratoire de Physiopathologie, Département de Biologie des Tumeurs, Institut Curie, Paris


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Relevant Article

Cross sectional study of conventional cervical smear, monolayer cytology, and human papillomavirus DNA testing for cervical cancer screening
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BMJ 2003 326: 733. [Abstract] [Full Text] [PDF]

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