Bacci ED, Wyrwich KW, Bender RH, Gries KS, Chen Y, Jain R, Konkol L, Merilainen MJ, Weng H. An adaptation of the profile of mood states (POMS) for use in adults with phenylketonuria (PKU): development of the PKUPOMS. Presented at the 2016 23rd Annual Conference of the International Society for Quality of Life Research (ISOQOL); October 2016. Copenhagen, Denmark. [abstract] Qual Life Res. 2016 Oct; 25(1):105.

AIMS: Adults with phenylketonuria (PKU) report experiencing a number of cognitive disorders, including worsened mood. However, no instrument has been developed to assess mood states in PKU. 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.

METHODS: In step one, cognitive interviews on the POMS among adults and adolescents (age C16 years) with PKU were conducted to identify and remove items that were poorly understood or considered irrelevant to PKU. In step two, POMS data from a Phase 3 study of adults with PKU was used to examine the remaining POMS items. Mokken scaling analysis (MSA) was used to calculate scalability coefficients, which provided information on how well each item within its respective domain, and each domain within the overall measure, provided an assessment of the same underlying concept. Items with weak scalability were removed, one by one, and the model refitted until all items/domains achieved Cmoderate scalability. In step three, the fit of the remaining items to the Rasch measurement model (threshold ordering, item non-redundancy, uni-dimensionality) was assessed. Finally, the psychometric properties (reliability, validity, and responsiveness) of the draft PKUPOMS were examined and cognitive interviews among adults with PKU were conducted to investigate the acceptability of the draft instrument in the target population.

Nine women (60 %) and six men (40 %) with PKU (mean age: 30.4 ± 12.9 years) identified 17 items for removal from the 58-POMS items (after removing the 7 Friendly domain items considered by the POMS developers too weak to be scored). Of the remaining 41 items, 10 were removed using MSA. Eleven additional items were removed during the Rasch analysis, and two items were rescored by combining two adjacent responses. The draft 20-item PKU-POMS instrument displayed strong psychometric properties over 6 domains (Anxiety, Depression, Anger, Activity, Tiredness, and Confusion); all items were well-understood in the 10 final cognitive interviews.

CONCLUSIONS: This detailed adaptation process incorporating qualitative and quantitative analyses yielded the 20-item PKU-POMS instrument designed for PKU clinical trial use to assess treatment efficacy on mood symptoms.

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