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Table 8 Reliability coefficients of the Parent PKU-QOL questionnaire at baseline in the parent evaluable population (n = 253)

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

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
  1. ICC: Intraclass Correlation Coefficient; Phe: phenylalanine; PKU: phenylketonuria; QOL: quality of life. Reliability coefficients ≥0.70 are set in bold type.