Genetic risk estimation by healthcare professionals.

OBJECTIVES

To assess whether healthcare professionals correctly incorporate the relevance of a favourable test outcome in a close relative when determining the level of risk for individuals at risk for Huntington's disease.

DESIGN AND

SETTING

Survey of clinical geneticists and genetic counsellors from 12 centres of clinical genetics (United Kingdom, 6; The Netherlands, 4; Italy, 1; Australia, 1) in May-June 2002. Participants were asked to assess risk of specific individuals in 10 pedigrees, three of which required use of Bayes' theorem.

PARTICIPANTS

71 clinical geneticists and 41 other healthcare professionals involved in genetic counselling.

MAIN OUTCOME MEASURES: Proportion of respondents correctly assessing risk in the three target pedigrees; proportion of respondents who were confident of their estimate.

RESULTS

50%-64% of respondents (for the three targets separately) did not include the favourable test information and incorrectly estimated the risks as being about equal to the prior risks; 77%-91% of these respondents were "sure" or "completely sure" that their estimations were correct. Twenty of the 112 respondents correctly estimated the risks for all three target pedigrees.

CONCLUSIONS

Clinical geneticists and genetic counsellors frequently use prior risks in situations where Bayes' theorem should be applied, leading to overestimations of the risk for an individual.