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Table 3 Final scaling/scoring structure of the four PKU-QOL questionnaires

From: Development and psychometric validation of measures to assess the impact of phenylketonuria and its dietary treatment on patients’ and parents’ quality of life: the phenylketonuria – quality of life (PKU-QOL) questionnaires

Modules

Domain scores

PKU-QOL items (for multi-item scores)

Child PKU-QOL (40 items)

Adolescent PKU-QOL (58 items)

Adult PKU-QOL (65 items)

Parent PKU-QOL (54 items)

PKU symptoms

Self-health rated status

  

Headaches

 

Stomach aches

 

Tiredness

 

Lack of concentration

 

Slow thinking

 

Trembling hands

   

 

Irritability

 

Aggressiveness

 

Moodiness

 

Sadness

 

Anxiety

 

PKU in general

Emotional impact of PKU

Unfairness having PKU

Worries about the future

 

Worries about future children

 

Disease acceptance

Self-esteem

Practical impact of PKU

Burden of care for PKU

Burden of physician visits

Maintaining activity at work

 

Time in administrative tasks

  

Missing work

   

Difficulty to do other things due to the burden of care for PKU

   

Social impact of PKU

Explain situation to others

Discussing PKU within family

Difficulty making friends

Impact on relationship with partner

  

Maintaining friendship

   

Impact of PKU on child’s siblings

   

Overall impact of PKU*

Items from Emotional, practical and social impact of PKU

Anxiety – blood tests

Anxiety having blood test in the arm

Anxiety having blood test in the finger

Impact of child anxiety – blood tests

Impact of child anxiety of blood test in the arm on parent

   

Impact of child anxiety of blood test in the finger on parent

   

Anxiety – Phe levels

 

Anxiety – Phe levels during pregnancy

   

 

Financial impact of PKU

   

Information on PKU

   

Administration of Phe-free protein supplements

Adherence to Phe-free protein supplements

Frequency of supplement intake

 

Adherence/compliance to supplement

Missing supplements because of school

 

  

Missing supplements because of work constraints

 

 

Guilt if poor adherence to Phe-free protein supplements

 

Impact of Phe-free protein supplements on family

 

Practical impact of Phe-free protein supplements

Embarrassment/shame taking supplements

 

Lack of spontaneity/freedom due to supplements

 

Difficulty eating out due to supplements

 

Difficulty travelling, transporting supplements for special event situations

 

Taste - Phe-free protein supplements

 

 

Management of Phe-free protein supplements

    

Dietary protein restriction

Food temptations

Temptation/adherence

 

Temptation not emotionally

 

Adherence to diet

Adherence/compliance to the diet

Eat forbidden things secretly

 

Change in diet because of school/college/university constraints

 

 

Change in diet because of work constraints

 

 

Eat forbidden food intentionally

    

Management of diet

Difficulty monitoring dietary protein restriction

   

Difficulty monitoring the amount of calories

   

Sadness to forbid food to child

   

Worry that child eats things secretly

   

Hard when child has to follow diet in front of others

   

Impact of diet on relationship with child

   

Practical impact of diet

Burden of weighing/estimating quantity of protein in food

 

Lack of spontaneity/freedom due to PKU diet

 

Difficulty eating out due to PKU diet

 

Need to plan meals in advance

 

Time-consuming aspects of the diet

 

Complexity cooking

 

Difficulty travelling, transporting PKU food for special event situations

 

Social impact of diet

Feeling different because of diet

 

Relationship within family

 

Temptation emotionally

 

Embarrassment/shame following diet

 

Isolation because of diet

 

Cooking for others

  

 

Overall impact of diet*

Items from practical and social impact of dietary protein restriction

 

 

Overall difficulty following diet

 

 

Guilt if diet not followed

 

Taste of low-protein food

 

 

Food enjoyment

 

  1. In bold*: Overall multi-item scores including items from different domains.
  2. Phe: phenylalanine; PKU: phenylketonuria.