Objective: To assess the impact of guidelines on drug use issued by a consensus conference on polycythemia vera held in Paris in June 1993. 32Phosphorus (32P) was recommended for patients over 70 and/or at risk, whereas pipobroman and hydroxyurea were recommended for patients under 70.

Methods: A questionnaire was sent to all 119 departments of nuclear medicine in France 1 year after the conference to find out whether and how often they measured plasma volume and red cell mass (the recommended diagnostic tests for polycythemia vera). Time-series analyses were performed on sales of 32P, pipobroman (both virtually exclusively prescribed for polycythemia), and hydroxyurea over a 4-year span (January 1992–December 1995).

Results: The average number of plasma volume determinations per year did not change significantly after the conference (22 ± 26 before vs 21 ± 25 after). 32P and pipobroman sales were stable until July 1993, when 32P sales decreased while pipobroman sales rose steadily. Hydroxyurea sales increased over the whole period with no change in trend after the guidelines were published.

Conclusions: The guidelines apparently influenced clinical practice since sales of drugs that are specifically used to treat polycythemia vera showed clear changes in trend after publication of the guidelines. This type of study seems to be an effective way of assessing the impact of consensus conferences.