Development of the PROMIS pediatric stigma and extension to the PROMIS pediatric stigma: skin item banks

Purpose To develop the PROMIS Pediatric Stigma (PPS) and Skin (PPS-Skin) by constructing a common metric for measuring stigma in children with various conditions, while capturing the unique features of each condition. Methods Data from 860 children, ages 8–17, with a diagnosis of epilepsy, pNF (neurofibromatosis type 1 associated neurofibroma plexform), MD (muscular dystrophy), cancer, or skin conditions recruited from three projects were analyzed. Children with epilepsy, pNF and MD (sample-1) completed the original 18-item Neuro-QoL Stigma, while children with cancer and skin conditions (e.g., atopic dermatitis, psoriasis, and genetic skin disorders; sample-2) completed a 16-item version and 6 additional skin related items. Exploratory factor analysis (EFA) and confirmatory analysis (CFA) were used to evaluate unidimensionality of 24 stigma items. Differential item functioning (DIF) was used to evaluate measurement equivalence on group, gender, age, and conditions. Item response theory model (IRT) was used to construct the final measure. Results Sufficient unidimensionality was supported by both EFA and CFA. No items showed significant DIF indicating stable measurement properties across groups of comparison. All items fit the IRT model and were able to be calibrated together to form the PPS which consists of 18 core items. The PPS-Skin (18 cores items + 6 skin items) was developed by calibrating 6 skin items onto the common metric as the PPS. Conclusions We used IRT techniques to successfully develop the PPS and the PPS-Skin, which share a common metric and account for unique and common concerns related to chronic conditions.