Table 7.
Reliability coefficients of the Child, Adolescent and Adult PKU-QOL questionnaires at baseline
| 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 |
ICC: Intraclass Correlation Coefficient; Phe: phenylalanine; PKU: phenylketonuria; QOL: quality of life. Reliability coefficients ≥0.70 are set in bold type.