Who is dentally anxious? Concordance between measures of dental anxiety.

Studies of the prevalence of dental anxiety in general population samples have produced estimates which range from a low of 2.6% to a high of 20.4%. It is not clear whether these reflect real differences among populations or whether they are the result of the use of different measures and different cut-off points. We undertook a large scale mail survey of dental anxiety in a random sample of the adult population living in Metropolitan Toronto designed to assess the performance of and agreement between three measures. These were Corah's DAS, the single item used by Milgrom and colleagues in Seattle and the ten-point fear scale used by Gatchel. These measures and their published cut-off points produced prevalence estimates of 10.9%, 23.4% and 8.2% respectively. While there was a significant association between scores on pairs of measures the agreement between them was far from perfect. Kappa values ranged from 0.37 to 0.56, indicating only fair to moderate agreement beyond chance. There was evidence to indicate that the dentally anxious subjects identified by each measure differed according to certain behavioural and other characteristics. The results of the study suggest the need to revisit the issue of measurement in studies of dental anxiety.