Co-development of a questionnaire to measure thought control in obsessive-compulsive disorder: A Delphi study on excessive rationalisation

An understudied aspect of obsessive-compulsive disorder (OCD) is the use of thought control strategies. Within this domain a new concept, excessive rationalisation, was developed in collaboration with people with OCD. Excessive rationalisation is a maladaptive cognitive strategy in which people attempt to argue with or explain away their unwanted thoughts. The present study used the Delphi method to co-design a questionnaire measure of excessive rationalisation. Twenty people with lived experience of OCD took part in four rounds. In the first round, responses to open-ended questions were used to generate a list of items which described the concept. In Rounds 2 and 3 participants rated the items in order to refine the initial list. In Round 4 participants chose the textual framing of the new questionnaire and ranked the items in order of how well they described excessive rationalisation. Round 1 generated in an initial list of 58 items, with an additional 3 items added in Round 2. Across the Delphi study 31 items were removed as they did not reach consensus, did not describe excessive rationalisation, or were redundant. The final questionnaire contained 30 items. Ninety per cent of participants (strongly) agreed that the new questionnaire measured the concept of excessive rationalisation.The new questionnaire measure of excessive rationalisation may be helpful for understanding more about cognitive strategies used by people with OCD, and how these contribute to treatment outcomes. Future work should seek to reduce the number of items in the questionnaire and test its psychometric properties.