Psychometric Properties of the Modified 5-D Itch Scale in a Burn Model System Sample of People With Burn Injury

The aim of this study is to evaluate the psychometric properties of the 4-dimension (4-D) itch scale, a modified version of the 5-dimension itch scale, in a sample of individuals with severe burn injury and/or burn injuries to hands, face, and/or feet. Four of the five domains of the 5-dimension itch scale (4-D) were administered to individuals who reported itching (N = 173) in the Burn Injury Model System Centers Program longitudinal study at either 5 or 10 years after injury. Analyses of the scale included evaluation of dimensionality, internal consistency, associations with other symptoms or quality of life measures, and an examination of floor and ceiling effects. Fit values from a one-factor confirmatory factor analysis were acceptable, supporting unidimensionality. Cronbach's α was 0.82, indicating good internal consistency. One item had a corrected item-total score correlation of less than 0.40. Associations between the 4-D and other measures were in the expected direction and magnitude. A negligible number of participants (no more than two) selected the lowest category for all items (ie, minimal floor effect) or the highest category for all items (ie, minimal ceiling effect). 4-D had acceptable psychometric properties in a sample of adult burn injury survivors; however, the scale could be improved by removing the item with a low correlation with the total score.