Background
Methods
Development of the questionnaires
France
|
Germany
|
Italy
|
Netherlands
|
Spain
|
Turkey
|
UK
|
Total
| |
---|---|---|---|---|---|---|---|---|
Exploratory interviews
| ||||||||
Nutritionists |
4
|
3
|
-
|
-
|
4
|
-
|
6
|
17
|
Pediatricians |
3
|
4
|
-
|
-
|
3
|
-
|
3
|
13
|
Adolescents 13–17 years with PKU |
4
|
4
|
-
|
-
|
4
|
-
|
4
|
16
|
Adults with PKU |
4
|
4
|
-
|
-
|
4
|
-
|
4
|
16
|
Parents of children 4–12 years with PKU |
4
|
4
|
-
|
-
|
4
|
-
|
4
|
16
|
Parents of adolescents 13–17 years with PKU |
0
|
0
|
-
|
-
|
3
|
-
|
0
|
3
|
Comprehension testing
| ||||||||
Children 6–11 years with PKU |
3
|
3
|
3
|
3
|
3
|
-
|
3
|
18
|
Adolescents 12–17 years with PKU |
4
|
4
|
4
|
4
|
4
|
-
|
4
|
24
|
Adults with PKU |
5
|
4
|
4
|
3
|
4
|
-
|
4
|
24
|
Parents of children with PKU |
5
|
5
|
5
|
5
|
5
|
-
|
6
|
31
|
Linguistic validation
| ||||||||
Children 6–11 years with PKU |
-
|
-
|
-
|
-
|
-
|
3
|
-
|
3
|
Adolescent 12–17 years with PKU |
-
|
-
|
-
|
-
|
-
|
3
|
-
|
3
|
Adults with PKU |
-
|
-
|
-
|
-
|
-
|
3
|
-
|
3
|
Parents of children with PKU |
-
|
-
|
-
|
-
|
-
|
3
|
-
|
3
|
Psychometric Validation study
| ||||||||
Children 9–11 year with PKU |
13
|
19
|
15
|
7
|
20
|
14
|
4
|
92
|
Adolescents 12–17 years with PKU |
10
|
20
|
26
|
10
|
20
|
20
|
4
|
110
|
Adults with PKU |
18
|
21
|
22
|
7
|
21
|
8
|
7
|
104
|
Parents of children ≤8 years with PKU |
10
|
8
|
8
|
6
|
8
|
6
|
6
|
52
|
Parents of children 9–11 years with PKU |
13
|
19
|
15
|
7
|
20
|
4
|
14
|
92
|
Parents of adolescents with PKU |
10
|
19
|
26
|
10
|
20
|
4
|
20
|
109
|
Validation study design
Statistical analyses
Scaling structure and the scoring rules of the four PKU-QOL questionnaires
Assessment of psychometric properties
Results
Population characteristics in the validation study
Evaluable population
Demographics
Child (9–11 yo) evaluable population
|
Adolescent (12–17 yo) evaluable population
|
Adult (>18 yo) evaluable population
|
Parent evaluable population
|
Children (0–18 yo) of the parent population
| ||
---|---|---|---|---|---|---|
(n = 92)
|
(n = 110)
|
(n = 104)
|
(n = 253)
|
(n = 253)
| ||
Age (years)
|
n (missing)
| 90 (2) | 110 (0) | 101 (3) | 244 (9) | 251 (2) |
Mean (SD)
| 9.8 (0.8) | 14.5 (1.6) | 25.8 (6.6) | 41.6 (6.5) | 10.7 (4.2) | |
Min – Max
| 9.0 – 11.0 | 12.0 – 17.0 | 18.0 – 45.0 | 24.0 – 66.0 | 0.0 – 17.0 | |
Sex
|
Male, n (%)
| 43 (46.7) | 56 (50.9) | 38 (36.5) | 69 (27.3) | 126 (49.8) |
PKU severity
|
Classical PKU*, n (%)
| 66 (71.7) | 75 (68.2) | 67 (64.4) | - | 172 (68.0) |
Scaling structure and scoring rules
Return rate
Quality of completion
Distribution of responses
Scaling structure
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 |
√
|
√
|
√
|
√
|
Scoring rules
-
for symptom scores, a higher score is associated with more frequent symptoms,
-
for adherence scores, a higher score is associated with a poorer adherence,
-
for other scores, a higher score is associated with a greater impact.
Psychometric properties
Validity
PKU-QOL scores
|
Child evaluable population (n = 92)
|
Adolescent evaluable population (n = 110)
| ||||||
---|---|---|---|---|---|---|---|---|
EF
|
PF
|
SoF
|
ScF
|
EF
|
PF
|
SoF
|
ScF
| |
Self-rated health status
| - | - | - | - | −0.26 | −0.23 | −0.22 | −0.16 |
Headaches
| −0.07 | −0.25 | −0.05 | −0.22 | −0.23 | −0.28 | −0.22 | −0.26 |
Stomach aches
| −0.33 | −0.06 | −0.06 | −0.17 | −0.16 | −0.23 | −0.25 | −0.11 |
Tiredness
| −0.13 | −0.34 | −0.21 | −0.30 | −0.23 | −0.22 | −0.15 | −0.18 |
Angry
| −0.38 | −0.36 | −0.24 | −0.30 | −0.30 | −0.08 | −0.27 | −0.08 |
Aggressiveness
| −0.08 | −0.13 | −0.00 | −0.10 | −0.31 | −0.20 | −0.21 | −0.31 |
Moodiness
| −0.13 | −0.26 | −0.11 | −0.25 | −0.28 | −0.10 | −0.10 | −0.27 |
Sadness
|
−0.41
| −0.33 | −0.33 | −0.23 | −0.31 | −0.17 | −0.23 | −0.16 |
Anxiety
| −0.26 | −0.05 | −0.31 | −0.12 | −0.27 | −0.18 | −0.27 | −0.10 |
Lack of concentration
| −0.15 | −0.32 | −0.33 | −0.36 | −0.21 | −0.19 | −0.27 |
−0.48
|
Slow thinking
| −0.24 |
−0.45
| −0.37 |
−0.43
| −0.32 |
−0.42
|
−0.42
| −0.36 |
Emotional impact of PKU
|
−0.45
| −0.22 | −0.28 | −0.33 |
−0.47
| −0.19 | −0.31 | −0.28 |
Practical impact of PKU
| −0.40 | −0.24 | −0.25 | −0.09 | −0.29 | −0.19 | −0.30 | −0.28 |
Social impact of PKU
| −0.39 | −0.38 |
−0.41
| −0.20 | −0.35 | −0.10 | −0.20 | −0.15 |
Overall impact of PKU
|
−0.54
| −0.35 |
−0.41
| −0.30 |
−0.49
| −0.21 | −0.31 | −0.31 |
Anxiety – blood test
| −0.13 | −0.05 | −0.04 | 0.05 | −0.11 | −0.16 | −0.05 | −0.03 |
Anxiety – blood Phe levels
|
−0.42
| −0.25 | −0.13 | −0.37 | −0.37 | −0.14 | −0.18 | −0.25 |
Adherence to Phe-free protein supplements
| −0.12 | −0.11 | 0.00 | −0.11 | −0.13 | −0.23 | −0.24 | −0.26 |
Practical impact of Phe-free protein supplements
| −0.23 | −0.18 | −0.21 | −0.16 |
−0.43
| −0.31 | −0.36 | −0.25 |
Guilt if poor adherence to Phe-free protein supplements
| 0.14 | 0.09 | 0.01 | 0.18 | −0.11 | 0.11 | 0.04 | 0.08 |
Relationships within family because of Phe-free protein supplements
| −0.30 | −0.18 | −0.18 | −0.11 | −0.16 | −0.11 | −0.14 | −0.37 |
Taste – Phe-free protein supplements
| −0.28 | −0.06 | −0.10 | −0.23 | −0.06 | 0.00 | 0.08 | −0.17 |
Food temptations
| −0.32 | −0.29 | −0.35 | −0.14 | −0.36 | −0.10 | −0.24 | −0.18 |
Adherence to dietary protein – restriction
| −0.03 | −0.14 | −0.01 | −0.11 | −0.39 | −0.09 | −0.29 | −0.18 |
Social impact of dietary protein restriction
| −0.40 |
−0.45
| −0.40 |
−0.47
| −0.37 | −0.19 | −0.34 | −0.34 |
Practical impact of dietary protein restriction
| - |
-
| - |
-
|
−0.44
| −0.24 | −0.30 | −0.40 |
Overall impact of dietary protein restriction
| - |
-
| - |
-
|
−0.45
| −0.27 | −0.33 | −0.35 |
Taste – specialty low-protein food
| −0.12 | 0.08 | 0.13 | −0.01 | −0.19 | −0.03 | −0.09 | −0.15 |
Food enjoyment
| −0.19 | −0.23 | −0.26 | −0.11 | 0.04 | 0.03 | −0.08 | −0.08 |
Guilt if dietary protein restriction not followed
| 0.01 | −0.08 | −0.10 | −0.03 | −0.24 | −0.03 | −0.16 | −0.03 |
Overall difficulty following dietary protein restriction
| −0.32 | −0.23 | −0.24 | −0.21 | −0.37 | −0.16 | −0.19 | −0.32 |
CHQ-PF28 scores
| |||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
PKU-QOL scores
|
PF
|
RP
|
GH
|
BP
|
PiT
|
PiE
|
RE
|
SE
|
MH
|
Be
|
FA
|
FC
|
CH
|
Child health status
| −0.24 | −0.24 |
−0.43
| −0.26 | −0.34 | −0.39 | −0.09 | −0.37 | −0.23 | −0.37 | −0.37 | −0.26 | 0.15 |
Headaches
| −0.06 | −0.10 | −0.29 | −0.32 | −0.18 | −0.21 | −0.12 | −0.25 | −0.29 | −0.25 | −0.22 | −0.16 | 0.16 |
Stomach aches
| −0.11 | −0.06 | −0.18 | −0.40 | −0.11 | −0.23 | −0.02 | −0.08 | −0.27 | −0.15 | −0.17 | −0.03 | 0.17 |
Tiredness
| −0.24 | −0.21 | −0.28 | −0.28 | −0.34 | −0.36 | −0.19 | −0.26 | −0.35 | −0.28 | −0.23 | −0.11 | −0.00 |
Lack of concentration
| −0.10 | −0.07 | −0.23 | −0.23 | −0.20 | −0.22 | −0.28 | −0.36 | −0.33 |
−0.57
| −0.22 | −0.17 | −0.06 |
Slow thinking
| −0.16 | −0.10 | −0.29 | −0.20 | −0.20 | −0.23 | −0.40 | −0.37 | −0.36 |
−0.47
| −0.26 | −0.17 | 0.03 |
Irritability
| −0.12 | −0.09 | −0.28 | −0.16 | −0.28 | −0.36 | −0.23 |
−0.42
|
−0.45
|
−0.54
| −0.27 | −0.29 | 0.03 |
Aggressiveness
| −0.16 | −0.22 | −0.19 | −0.12 | −0.26 | −0.28 | −0.31 | −0.31 | −0.37 |
−0.49
| −0.28 | −0.24 | −0.09 |
Moodiness
| −0.14 | −0.18 | −0.21 | −0.26 | −0.32 |
−0.43
| −0.31 | −0.40 |
−0.43
|
−0.53
| −0.37 | −0.24 | −0.07 |
Sadness
| −0.16 | −0.10 | −0.25 | −0.32 | −0.36 | −0.30 | −0.36 | −0.38 |
−0.43
| −0.35 | −0.28 | −0.16 | 0.03 |
Anxiety
| −0.18 | −0.15 | −0.24 | −0.18 | −0.24 | −0.16 | −0.34 | −0.39 |
−0.41
| −0.20 | −0.21 | −0.21 | 0.01 |
Emotional impact of PKU
| −0.14 | −0.15 | −0.33 | −0.21 | −0.23 | −0.40 | −0.04 | −0.22 | −0.29 | −0.26 | −0.29 | −0.27 | −0.03 |
Practical impact of PKU
| −0.20 | −0.18 | −0.35 | −0.21 | −0.33 | −0.39 | −0.15 | −0.24 | −0.37 | −0.34 |
−0.42
| −0.25 | 0.07 |
Social impact of PKU
| −0.20 | −0.18 | −0.29 | −0.24 | −0.26 | −0.35 | −0.20 | −0.25 | −0.33 | −0.31 | −0.37 | −0.36 | −0.03 |
Overall impact of PKU
| −0.21 | −0.20 | −0.39 | −0.26 | −0.31 |
−0.46
| −0.12 | −0.29 | −0.37 | −0.35 |
−0.44
| −0.34 | −0.02 |
Anxiety – blood test
| −0.15 | −0.13 | −0.14 | −0.05 | −0.21 | −0.22 | −0.03 | −0.01 | −0.15 | −0.08 | −0.27 | −0.06 | 0.08 |
Impact of anxiety – blood test
| −0.19 | −0.20 | −0.24 | −0.10 | −0.26 | −0.26 | −0.09 | 0.02 | −0.14 | −0.05 | −0.29 | −0.03 | 0.26 |
Anxiety – blood Phe levels
| −0.06 | −0.06 | −0.25 | −0.13 | −0.13 |
−0.42
| −0.09 | −0.06 | −0.28 | −0.24 | −0.19 | −0.09 | 0.05 |
Financial impact of PKU
| −0.12 | −0.05 | −0.20 | −0.19 | −0.19 | −0.29 | −0.06 | −0.05 | −0.15 | −0.26 | −0.24 | −0.20 | 0.03 |
Information on PKU
| −0.14 | −0.19 | −0.25 | −0.26 | −0.14 | −0.24 | −0.14 | −0.30 | −0.16 | −0.24 | −0.19 | −0.27 | 0.00 |
Adherence to Phe-free protein supplements
| −0.09 | −0.16 | −0.10 | −0.13 | −0.11 | −0.08 | −0.22 | −0.24 | −0.21 | −0.28 | −0.12 | −0.07 | 0.03 |
Management of Phe-free protein supplements
| −0.03 | −0.12 | −0.09 | −0.10 | −0.28 | −0.21 | −0.05 | −0.07 | −0.18 | −0.28 | −0.22 | −0.14 | −0.06 |
Practical impact of Phe-free protein supplements
| −0.15 | −0.23 | −0.19 | −0.12 | −0.17 | −0.18 | −0.04 | −0.06 | −0.25 | −0.10 | −0.38 | −0.26 | −0.03 |
Guilt if poor adherence to Phe-free protein supplements
| −0.14 | −0.07 | −0.27 | −0.09 | −0.10 | −0.27 | −0.11 | 0.08 | −0.20 | −0.10 | −0.14 | −0.05 | 0.15 |
Relationships within family because of Phe-free protein supplements
| −0.17 | −0.21 | −0.15 | −0.26 | −0.33 | −0.22 | −0.15 | −0.16 | −0.24 | −0.34 | −0.32 | −0.23 | −0.02 |
Adherence to dietary protein restriction
| −0.04 | −0.09 | −0.17 | −0.08 | −0.19 | −0.11 | −0.14 | −0.15 | −0.09 | −0.24 | −0.16 | −0.10 | 0.07 |
Management of dietary protein restriction
| −0.12 | −0.16 | −0.26 | −0.25 | −0.30 | −0.40 | −0.24 | −0.34 | −0.35 |
−0.49
|
−0.41
| −0.29 | −0.04 |
Practical impact of dietary protein restriction
| −0.15 | −0.24 | −0.24 | −0.28 | −0.30 | −0.33 | −0.10 | −0.30 | −0.32 | −0.33 |
−0.46
| −0.39 | −0.14 |
Food enjoyment
| −0.11 | −0.06 | −0.19 | −0.28 | −0.21 | −0.14 | −0.07 | −0.26 | −0.27 | −0.24 | −0.28 | −0.28 | 0.07 |
Guilt if dietary protein restriction not followed
| −0.15 | −0.04 | −0.15 | −0.07 | −0.05 | −0.31 | −0.12 | −0.00 | −0.15 | −0.07 | −0.12 | −0.04 | 0.04 |
PKU-QOL scores
|
SF-36 scores
| |||||||
---|---|---|---|---|---|---|---|---|
PF
|
RP
|
BP
|
GH
|
VT
|
SF
|
RE
|
MH
| |
Self-rated health status
| −0.37 | −0.22 | −0.30 |
−0.58
|
−0.57
| −0.36 | −0.29 |
−0.50
|
Headaches
| −0.20 | −0.26 | −0.39 | −0.31 | −0.29 |
−0.41
| −0.30 | −0.35 |
Stomach aches
| −0.17 | −0.19 | −0.40 | −0.30 | −0.34 | −0.26 | −0.33 | −0.37 |
Tiredness
| −0.28 | −0.34 | −0.30 | −0.40 |
−0.52
| −0.40 | −0.32 | −0.39 |
Lack of concentration
| −0.25 |
−0.59
| −0.37 | −0.40 |
−0.52
|
−0.51
|
−0.56
|
−0.60
|
Slow thinking
| −0.27 | −0.36 | −0.29 | −0.36 | −0.32 |
−0.44
|
−0.47
|
−0.43
|
Trembling hands
| −0.16 | −0.21 | −0.19 | −0.31 | −0.31 | −0.19 | −0.25 | −0.28 |
Irritability
| −0.23 |
−0.44
| −0.32 | −0.29 | −0.20 | −0.31 |
−0.40
| −0.39 |
Aggressiveness
| −0.22 | −0.36 | −0.21 | −0.24 | −0.22 | −0.31 | −0.31 | −0.24 |
Moodiness
| −0.21 | −0.40 |
−0.45
| −0.38 |
−0.41
|
−0.54
|
−0.50
|
−0.53
|
Sadness
| −0.21 |
−0.44
|
−0.48
|
−0.49
| −0.39 |
−0.61
|
−0.56
|
−0.66
|
Anxiety
| −0.16 | −0.31 | −0.26 | −0.31 | −0.29 | −0.37 |
−0.43
|
−0.47
|
Emotional impact of PKU
|
−0.41
| −0.31 | −0.35 |
−0.43
| −0.34 | −0.35 | −0.31 | −0.39 |
Practical impact of PKU
| −0.05 | −0.38 | −0.18 | −0.38 | −0.38 | −0.38 |
−0.47
| −0.38 |
Social impact of PKU
| −0.34 | −0.32 | −0.30 | −0.40 | −0.30 |
−0.48
| −0.35 | −0.39 |
Overall impact of PKU
| −0.27 |
−0.42
|
−0.42
|
−0.53
| −0.32 |
−0.53
|
−0.45
|
−0.48
|
Anxiety – blood test
| 0.05 | −0.03 | −0.27 | −0.16 | −0.12 | −0.32 | −0.22 | −0.25 |
Anxiety – Phe levels
| −0.19 | −0.11 | −0.21 | −0.28 | −0.19 | −0.25 | −0.17 | −0.15 |
Anxiety – Phe levels during pregnancy
| −0.11 | 0.11 | −0.03 | −0.02 | −0.00 | −0.05 | 0.06 | −0.13 |
Financial impact of PKU
| −0.11 | −0.05 | −0.05 | 0.14 | 0.03 | 0.01 | 0.03 | 0.08 |
Information on PKU
| −0.08 | −0.11 | −0.15 | −0.12 | −0.08 | −0.17 | −0.22 | −0.19 |
Adherence to Phe-free protein supplements
| −0.10 | −0.28 | −0.25 | −0.14 | −0.29 | −0.35 | −0.38 | −0.18 |
Practical impact of Phe-free protein supplements
| −0.13 | −0.13 | −0.11 |
−0.41
|
−0.43
| −0.33 | −0.25 | −0.37 |
Guilt if poor adherence to Phe-free protein supplements
| −0.12 | −0.16 | −0.23 | −0.22 | −0.13 | −0.30 | −0.13 | −0.23 |
Relationships within family because of Phe-free protein supplements
| −0.02 | −0.01 | −0.20 | −0.15 | −0.13 | −0.13 | 0.01 | −0.09 |
Taste – Phe-free protein supplements
| 0.07 | 0.12 | 0.04 | −0.24 | −0.25 | −0.18 | −0.00 | 0.00 |
Food temptations
| −0.14 | −0.40 | −0.19 | −0.21 | −0.25 | −0.37 | −0.31 | −0.33 |
Adherence to dietary protein restriction
| −0.03 | −0.29 | −0.13 | −0.06 | −0.17 | −0.24 | −0.29 | −0.29 |
Social impact of dietary protein restriction
| −0.12 | −0.40 | −0.20 |
−0.43
|
−0.44
|
−0.50
|
−0.50
|
−0.49
|
Practical impact of dietary protein restriction
| −0.21 | −0.25 | −0.11 | −0.38 |
−0.59
|
−0.44
| −0.39 |
−0.46
|
Overall impact of dietary protein restriction
| −0.23 | −0.33 | −0.17 |
−0.45
|
−0.57
|
−0.54
|
−0.44
|
−0.49
|
Taste – specialty low-protein food
| −0.09 | −0.31 | −0.27 | −0.33 | −0.25 | −0.34 |
−0.41
| −0.33 |
Food enjoyment
| −0.19 | −0.28 | −0.16 | −0.36 | −0.34 |
−0.41
| −0.38 | −0.29 |
Guilt if dietary protein restriction not followed
| −0.17 | −0.15 | −0.21 | −0.30 | −0.10 | −0.33 | −0.12 | −0.16 |
Overall difficulty following dietary protein restriction
| −0.33 |
−0.47
| −0.21 | −0.38 |
−0.46
|
−0.46
| −0.34 | −0.33 |
Reliability
Internal consistency reliability
Child PKU-QOL (n = 92)
|
Adolescent PKU-QOL (n = 110)
|
Adult PKU-QOL (n = 104)
| ||||
---|---|---|---|---|---|---|
Cronbach α |
ICC
|
Cronbach α |
ICC
|
Cronbach α |
ICC
| |
Self-rated health status
| - | - | - | 0.49 | - | 0.67 |
Headaches
| - | 0.37 | - | 0.52 | - | 0.59 |
Stomach aches
| - | 0.33 | - | 0.34 | - | 0.61 |
Tiredness
| - | 0.27 | - | 0.51 | - | 0.62 |
Irritability/Anger
| - | 0.45 | - | 0.53 | - | 0.42 |
Aggressiveness
| - | 0.44 | - | 0.64 | - | 0.53 |
Moodiness
| - | 0.47 | - | 0.59 | - | 0.66 |
Sadness
| - | 0.35 | - | 0.52 | - | 0.57 |
Anxiety
| - | 0.44 | - |
0.70
| - | 0.60 |
Lack of concentration
| - | 0.47 | - | 0.60 | - | 0.69 |
Slow thinking
| - | 0.55 | - | 0.61 | - | 0.63 |
Trembling hands
| - | - | - | - | - |
0.75
|
Emotional impact of PKU
| 0.37 | 0.60 |
0.70
|
0.83
|
0.71
|
0.84
|
Practical impact of PKU
| 0.43 | 0.45 | 0.47 |
0.75
| 0.50 |
0.70
|
Social impact of PKU
| 0.59 |
0.70
| 0.45 |
0.83
| 0.63 |
0.77
|
Overall impact of PKU
| 0.69 | 0.67 |
0.80
|
0.88
|
0.79
|
0.84
|
Anxiety – blood test
| 0.26 | 0.64 | 0.61 |
0.95
|
0.77
|
0.87
|
Anxiety – blood Phe levels
| - | 0.64 | - |
0.76
| - | 0.63 |
Anxiety – blood Phe levels during pregnancy
| - | - | - | - | - |
0.71
|
Financial impact of PKU
| - | - | - | - | - | 0.65 |
Information on PKU
| - | - | - | - | - | 0.60 |
Adherence to Phe-free protein supplements
| 0.46 | 0.48 |
0.70
| 0.64 | 0.67 |
0.84
|
Practical impact of Phe-free protein supplements
| - | 0.29 |
0.82
|
0.87
| 0.67 | 0.67 |
Guilt if poor adherence to Phe-free protein supplements
| - | 0.60 | - | 0.59 | - | 0.67 |
Relationships within family because of Phe-free protein supplements
| - |
0.72
| - | 0.69 | - | 0.57 |
Taste – Phe-free protein supplements
| - |
0.81
| - |
0.88
| - |
0.76
|
Food temptations
| 0.63 | 0.55 |
0.77
|
0.74
|
0.78
| 0.68 |
Adherence to dietary protein restriction
| 0.25 | 0.43 | 0.59 |
0.80
|
0.81
|
0.77
|
Social impact of dietary protein restriction
|
0.74
| 0.58 |
0.88
|
0.86
|
0.77
|
0.83
|
Practical impact of dietary protein restriction
| - | - |
0.74
|
0.71
|
0.78
|
0.70
|
Overall impact of dietary protein restriction
| - | - |
0.74
|
0.80
|
0.88
|
0.79
|
Taste – specialty low-protein food
| - | 0.47 | - | 0.57 | - |
0.73
|
Food enjoyment
| - | 0.21 | - | 0.31 | - |
0.77
|
Guilt if dietary protein restriction not followed
| - | 0.60 | - | 0.61 | - |
0.74
|
Overall difficulty following dietary protein restriction
| - | 0.55 | - | 0.59 | - | 0.54 |
Parent PKU-QOL scores
|
Cronbach’s α
|
ICC
|
---|---|---|
Child health status
| - | 0.59 |
Headaches
| - | 0.47 |
Stomach aches
| - | 0.41 |
Tiredness
| - | 0.58 |
Irritability
| - | 0.65 |
Aggressiveness
| - | 0.69 |
Moodiness
| - | 0.61 |
Sadness
| - | 0.48 |
Anxiety
| - | 0.60 |
Lack of concentration
| - | 0.63 |
Slow thinking
| - | 0.60 |
Emotional impact of PKU
| 0.63 |
0.78
|
Practical impact of PKU
|
0.74
|
0.76
|
Social impact of PKU
|
0.72
|
0.80
|
Overall impact of PKU
|
0.84
|
0.84
|
Anxiety – blood test
|
0.73
|
0.85
|
Impact of anxiety – blood test
|
0.76
|
0.78
|
Anxiety – blood Phe levels
| - |
0.79
|
Financial impact of PKU
| - |
0.78
|
Information on PKU
| - | 0.63 |
Adherence to Phe-free protein supplements
| - | 0.42 |
Management of Phe-free protein supplements
| - | 0.61 |
Practical impact of Phe-free protein supplements
|
0.77
| 0.66 |
Guilt if poor adherence to Phe-free protein supplements
| - | 0.59 |
Relationships within family because of Phe-free protein supplements
| - | 0.59 |
Adherence to dietary protein restriction
| - | 0.29 |
Management of dietary protein restriction
|
0.85
|
0.78
|
Practical impact of dietary protein restriction
|
0.82
|
0.79
|
Food enjoyment
| - | 0.35 |
Guilt if dietary protein restriction not followed
| - |
0.70
|