How Can We Best Assess Quality of Life and Neuropsychological Function in Patients with PKU?

What you need to know

• Experts recommend 9 validated tools to assess quality of life, executive function, IQ, and ADHD symptoms in Brazilian patients with phenylketonuria (PKU)
• These assessments can help monitor treatment effectiveness and identify areas needing intervention
• Using standardized tools allows for more consistent evaluation and comparison of outcomes across patients and centers

Background on PKU and its effects

Phenylketonuria (PKU) is a genetic disorder that affects how the body processes an amino acid called phenylalanine. People with PKU cannot properly break down phenylalanine, causing it to build up to harmful levels in the blood and brain. If left untreated, this can lead to serious health problems, including brain damage and intellectual disabilities.

While early detection through newborn screening and lifelong dietary treatment have greatly improved outcomes, many patients with PKU still experience some cognitive and psychological effects. Research has found that 20-30% of patients who begin treatment early still show deficits in certain mental abilities, like memory, processing speed, and executive function (the mental skills needed to plan, focus, remember instructions, and multitask). Patients with PKU also have higher rates of conditions like anxiety, depression, and attention deficit hyperactivity disorder (ADHD).

Given these potential effects, it’s important for doctors to regularly assess cognitive function and quality of life in patients with PKU. However, there has not been a standard set of assessment tools recommended for use in Brazil. This paper aims to address that gap by providing expert recommendations on validated tools that can be used to evaluate Brazilian patients.

Recommended assessment tools

A group of six Brazilian PKU experts met to discuss and recommend assessment tools that:

1. They had experience using in clinical practice
2. Could feasibly be administered as part of routine care
3. Were accessible for use in the public health system

Based on these criteria, they recommended 9 tools across four key areas:

Quality of Life Assessments

1. PedsQL (Pediatric Quality of Life Inventory): For children/teens ages 5-18 and parents of children ages 2-18
2. SF-36 (Short Form Health Survey): For individuals 14 and older
3. WHOQOL-BREF (World Health Organization Quality of Life Brief Version): For individuals 12 and older

These questionnaires evaluate various aspects of quality of life, including physical, emotional, social, and school/work functioning. While not specific to PKU, they allow comparison to general population norms.

Executive Function

4. BRIEF (Behavior Rating Inventory of Executive Function): Parent questionnaire for ages 5-18
5. Bayley-III: For infants/toddlers up to 42 months old

The BRIEF assesses skills like inhibition, emotional control, working memory and planning/organization. The Bayley Scales evaluate cognitive, language and motor development in young children.

Intelligence Quotient (IQ)

6. WASI (Wechsler Abbreviated Scale of Intelligence): For ages 6-89
7. SON-R 2½-7[a]: For ages 2.5-7 years

These provide measures of overall cognitive ability and reasoning skills.

ADHD Symptoms

8. MTA-SNAP-IV: Parent/teacher questionnaire for ages 5-17
9. ASRS (Adult ADHD Self-Report Scale): Self-assessment for adults 17+

These evaluate symptoms of inattention, hyperactivity and impulsivity associated with ADHD.

Benefits of standardized assessment

Using validated, standardized tools to assess PKU patients offers several important benefits:

Consistent evaluation: Having a standard set of measures allows for more consistent assessment across different doctors and treatment centers. This makes it easier to track an individual patient’s progress over time.

Comparison to norms: Many of these tools have data on typical scores for the general population. This allows doctors to see how a patient’s functioning compares to what would be expected for their age.

Early identification of issues: Regular screening can help catch cognitive or psychological issues early, allowing for timely intervention.

Treatment monitoring: These assessments can be used to evaluate how well treatments are working. For example, if a patient starts a new medication, changes in their test scores could show if it’s helping improve their cognitive function.

Research: Using common measures across patients and studies makes it easier to combine and compare data. This can lead to better understanding of PKU and its treatments.

Implementing the assessments

The experts emphasize that these tools should be feasible to use in routine clinical practice. Most can be completed in 15-30 minutes. They recommend trying to do all relevant assessments on the same day, but keeping the total time under 75 minutes to avoid fatigue.

For young children, they suggest using tools like the Bayley Scales as early as possible. Early assessment allows for early intervention if any delays are detected.

While some of the assessments (like IQ tests) require a trained psychologist to administer, others are questionnaires that can be completed by patients or parents. This allows for efficient gathering of information even if a center has limited access to specialists.

Conclusions

• The recommended tools provide a comprehensive assessment of quality of life, cognitive function, and ADHD symptoms in PKU patients across different age groups
• Using these standardized measures can improve the quality and consistency of care for Brazilian PKU patients
• Regular assessment allows doctors to monitor patients’ functioning over time and adjust treatment as needed
• Further work is still needed to validate PKU-specific quality of life measures for use in Brazil

By providing these recommendations, the authors hope to encourage more routine use of these validated tools in PKU care across Brazil. This can lead to better monitoring of patient outcomes and ultimately improved care for individuals living with PKU.