Background: The impact on quality of life (QOL) caused by atopic dermatitis (AD) has been quantified in children and adults using established QOL measures. However, these are not suitable for use in infants under the age of 4 years, when AD usually develops.
Objectives: To validate a new parent-generated QOL questionnaire, the Infants' Dermatitis QOL Index (IDQOL), which measures the impact of AD on the infant, and to provide further validation of the Family Dermatitis Index (FDI), which measures the impact of a child's dermatitis on the family.
Methods: Parents of 102 predominately caucasian infants under 4 years with AD (34 postal and 68 outpatients) were asked to complete the IDQOL and the FDI on two separate occasions to test for repeat validity. The Infants' Behavioural Check List (BCL) was also given to the study group and to parents of 22 normal control infants. Post-treatment IDQOL and FDI questionnaires were obtained from 25 of the study group.
Results: The return rate for initial questionnaires was 87.3% (61 boys, 28 girls) and for retest 70.6%. The mean score for IDQOL was 7.89 and for FDI 8.87. Spearman rank correlation between the IDQOL and FDI was high (r = 0.87). Correlations of IDQOL and FDI with clinical severity assessment by parents were lower (r = 0.58 for IDQOL and r = 0.5 for FDI). Test-retest data for IDQOL and FDI confirmed repeatability, there being negligible differences between the pairs using the method of Bland and Altman. The three highest scoring questions for IDQOL referred to itching and scratching, mood change and sleep disturbance. For the FDI they were parental sleep disturbance, tiredness and exhaustion, and emotional distress. Post-treatment questionnaires from 25 patients indicated sensitivity to clinical change with both IDQOL and FDI. Parameters of behaviour measured using the BCL in 82 study infants and 22 controls showed greater problems with frequent night-time wakening (43% vs. 4.5%) and miserable mood changes (24.4% vs. 9%) in the study infants.
Conclusions: Initial validation of the IDQOL and further validation of the FDI show good test-retest repeatability and apparent sensitivity to change with treatment. The effect on health-related QOL as measured by these methods is poorly correlated with clinical severity, confirming that QOL measures should be used in conjunction with clinical measures for global assessments of disease impact. This work requires further validation but suggests that QOL measures may be useful as outcome measures in clinical practice and research. Their simple construction allows quick and easy use, which is particularly valuable in large-scale and postal studies.