Do parents of children with caries choose to opt out of positive consent dental surveys in Wales?

Background Recently, positive consent has been required for dental surveys in some parts of the UK. Concerns have been raised that when positive consent is used participation is reduced in deprived areas and reported caries levels are biased as a consequence. This paper analyses caries data collected under positive and negative consent arrangements to explore this issue further. Method Retrospective analysis of response rates by deprivation fifth and by caries experience of participating children in NHS coordinated dental surveys in Wales undertaken from 2001/2 until 2005/6 using negative consent and in 2007/8 using positive consent. Results Across Wales, the change from negative to positive consent was associated with greatly decreased participation. In comparison with previous surveys there was a large increase in children sampled but not examined. The decrease in the proportion of children sampled, who were examined and found to have no decay was similar across all deprivation fifths, with no obvious deprivation-related trend. There was a much larger reduction in the number of children with decay who participated across all quintiles of deprivation. Conclusion Caries status could be a more important factor than deprivation regarding opting out of the survey. It appears that children with caries are more likely to be opted out of the survey than similarly deprived peers without caries. Parents appear to be more likely to opt children with caries out of dental surveys when positive consent is used. These findings have significant implications for targets aimed at improving oral health which were set before the change in consent procedures, but reported upon after.