An Adaptation of the Profile of Mood States for Use in Adults With Phenylketonuria

Adults with phenylketonuria (PKU) experience disturbances in mood. This study used qualitative and quantitative techniques to adapt the 65-item Profile of Mood States (POMS) for the assessment of key mood domains in adults with PKU. First, cognitive interviews on 58 POMS items (excluding 7 Friendliness domain items) among 15 adults and adolescents (age ≥16 years) with PKU were conducted to eliminate items poorly understood or considered irrelevant to PKU; 17 items were removed. Next, the remaining POMS items were quantitatively examined (Mokken scaling and Rasch analysis) in 115 adult patients with PKU. An additional 21 items were removed iteratively, resulting in the 20-item draft PKU-POMS. Finally, the psychometric properties of the draft PKU-POMS were examined. The instrument displayed strong psychometric properties (reliability, validity, and responsiveness) over 6 domains (Anxiety, Depression, Anger, Activity, Tiredness, and Confusion) and all items were well understood in the final cognitive interviews with 10 adults with PKU.