How many response levels do children distinguish on faces scales for pain assessment?

Faces scales are one of the most commonly used instruments to assess pain intensity in children. Most available faces scales present five to seven faces. The present research was conducted to investigate the ability of 4- to 7-year-old children to distinguish the response categories of different faces scales. In the first study, 121 children were asked to rate painful situations on a 3- and a 6-level faces scale commencing with a smiling 'no pain' face. Children were divided into two age groups (4-5 and 6-7 years). Investigations of the category functioning were performed with a rating scale Rasch model for each age group. Results revealed the low performances of the 6-level faces scale as compared to the 3-level faces scale and also the difficulty children experienced in scoring the imaginary painfulness of items. Consequently, a second study was conducted. In this second study, 76 children were asked to rate pictures depicting painful situations on a 3-level faces scale beginning with a neutral 'no pain' face. Results of this second study confirmed an improvement in the ability to distinguish the three response categories with age. The 4-5 year-old children could only distinguish two response categories and the 6-7 year-old children were able to discern the three levels of the 3-level faces scale. In conclusion, young children do not distinguish as many faces as proposed by the majority of available faces scales. These results strongly recommend a reduction in the number of response levels of faces scales for pain assessment in children.