Utilisation of a think-aloud protocol to validate a self-reported periodontitis questionnaire

Objectives: The gold standard approach to diagnose periodontitis is based on clinical examination and radiographic investigations. This, however, is expensive, tedious, and not feasible in population-level assessments. The self-reported periodontitis questionnaire offers great benefit to facilitate larger epidemiological surveys. There is limited evidence on cognitive validation of self-reported periodontitis questionnaire. This study employed a think aloud approach to investigate if participants interpreted, comprehended, and understood the items in a self-reported periodontitis questionnaire, in the same way as researchers’ intended.

Methods: 20 adults, resident of the UK and fluent in English participated in online recorded think aloud interviews. The self-reported periodontitis questionnaire consists of 15 questions and 2 open ended questions. The interviews were then transcribed and coded by two independent researchers according to predefined categories representing comprehension and conventional content analysis was used to analyse open-ended data.

Results: The think aloud approach revealed that most of the questions in the self-reported periodontitis questionnaire were well understood by the participants. Two items, however, were identified as problematic: one was misinterpreted, and another question was not understood by most of the participants. Qualitative conventional content analysis of open-ended questions reiterated and complemented the findings of the think aloud study. Further questions coded as problematic for 3 or more participants were then considered for rephrasing.

Conclusions: This study revealed the interpretation and understanding of self-reported periodontitis questions by English speaking UK residents and highlighted the probable reason for lower sensitivity values of the self-reported periodontitis questionnaire.

Clinical significance: This study employed think-aloud approach to capture the thought process of the participants as they answered questions on self-reported periodontitis questionnaire. Overall, the questionnaire was well received by the participants, however, some questions were misunderstood/misinterpreted. This study highlights the potential information bias if participants do not understand the questions in epidemiological surveys.