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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   
Stomach aches  
Lack of concentration  
Slow thinking  
Trembling hands      
PKU in general Emotional impact of PKU Unfairness having PKU
Worries about the future  
Worries about future children  
Disease acceptance
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.