Assessing the Content Validity of the Investigator-Rated ADHD Rating Scale Version IV Instrument Inattention Subscale for Use in Adults With Phenylketonuria

Abstract

Content validity of the 18-item Investigator-Rated Attention-Deficit Hyperactivity Disorder (ADHD) Rating Scale IV (I-ADHD RS-IV) with adult prompts was investigated using qualitative interviews of US clinicians who had prior experience rating adults with phenylketonuria (PKU) using the I-ADHD RS-IV. Fourteen qualitative interviews were conducted to obtain key symptom experiences of adults with PKU and assessed the relevance, clarity, and administration of the I-ADHD RS-IV. Participants (n = 13, 92.9%) endorsed the inattention symptoms as key experiences by adults with PKU and endorsed the instrument as fit for purpose for adults with PKU. Participants generally reported low frequencies of occurrence for the 9 I-ADHD RS-IV hyperactivity/impulsivity items. Despite some clinicians’ concerns for the lack of patient self-awareness, the participants reported no difficulty selecting a rating on these items. This in-depth study of the content validity of the I-ADHD RS-IV provides evidence that this clinician-reported instrument captures the severity of important inattention symptoms in adults with PKU.

Management of early treated adolescents and young adults with phenylketonuria: Development of international consensus recommendations using a modified Delphi approach

“…When this initial screening is positive, the entire BRIEF should be completed to understand the spectrum and severity of deficits in executive functioning. It is recognized that results obtained on screening tools, such as the BRIEF, may reflect the impact of limited self-awareness, which can be present in some patients with PKU due to the neurocognitive impairments, complicating self-assessment of symptoms [69,70]. In such situations, alternate versions of the BRIEF are available, permitting perspectives from another informant (e.g., spouse, parent or caregiver), while rating scales could also be combined with more objective performancebased tasks.…”

A non-interventional observational study to identify and validate clinical outcome assessments for adults with phenylketonuria for use in clinical trials

“…Furthermore, adults with PKU may lack self-awareness due to neuropsychological impairments. This lack of self-awareness hampers self-rating of symptoms, which may seem evident to a clinician or familiar observer [20] . Additionally, patients with PKU may be reluctant to attribute symptoms that they are experiencing to their PKU.…”