Development of Health-related Quality of Life Instrument for Patients With Cystinosis

Semi-structured interviews are conducted to create a pilot test version of the preliminary disease-specific HrQoL tool (QUALIFY). The results of the qualitative analysis will be used to derive an initial item list and response categories of the preliminary questionnaire.

A pilot-testing of the preliminary version of the QUALIFY questionnaire, including a cognitive debriefing, are performed, so that young patients and parents report on the comprehensibility, completeness, and cultural applicability of the questionnaire from their perspective.

A field- and re-test for psychometric assessment of the final version of the QUALIFY questionnaire is performed.

The 12-item short form of the DISABKIDS Questionnaire is used to assess the HrQoL of children and adolescents with chronic medical conditions from their own as well as their parents' perspectives. The questionnaire consists of three domains: Mental (4 items), social (4 items) and physical (4 items). One composite score can be calculated.

Higher scores indicate better HrQoL.

For the age group 2-4 years, the generic HrQoL of toddlers is assessed via parent report. It consists of 21 items and describes 4 dimensions (Physical Functioning (8 items) Emotional Functioning (5 items) Social Functioning, (5 items), School Functioning (3 items)). The following Scores can be computed: Total Scale Score (21 items); Physical Health Summary Score (8 items); Psychosocial Health Summary Score (15 items).

The 23-item PedsQL™ Generic Core Scales measure generic HrQoL in children, adolescents, and young adults in self-report as well as proxy report. There are four multidimensional scales (Physical Functioning (8 items) Emotional Functioning (5 items) Social Functioning, (5 items), School Functioning (5 items)) and three summary scores: Total Scale Score (23 items); Physical Health Summary Score (8 items); Psychosocial Health Summary Score (15 items).

In both versions, scores are transformed to a 0 to 100 scale and higher scores indicate better HrQoL.

The PedsQL™ Infant Scales measure generic HrQoL in infants aged 1-12 and 13-24 months in proxy report.

The version for infants ages 1-12 months consists of 36 items. There are five multidimensional scales (Physical Functioning (6 items), Physical Symptoms (10 items), Emotional Functioning (12 items) Social Functioning, (4 items), Cognitive Functioning (4 items)).

The version for infants ages 13-24 months consists of 45 items. There are five multidimensional scales (Physical Functioning (9 items), Physical Symptoms (10 items), Emotional Functioning (12 items) Social Functioning, (5 items), Cognitive Functioning (9 items)).

In both versions, scores are transformed to a 0 to 100 scale and higher scores indicate better HrQoL. Three summary scores can be calculated: Total Scale Score (all items); Physical Health Summary Score (using items of Physical Functioning and Physical Symptoms); Psychosocial Health Summary Score (Emotional, Social, and Cognitive Functioning items).

The 36-item PedsQL™ Family Impact Module describes 8 dimensions: parent self-reported physical functioning (6 items), emotional functioning (5 items), social functioning (4 items), and cognitive functioning (5 items), communication (3 items), worry (5 items), as well as parent-reported family daily activities (3 items) and family relationships (5 items).

Scores are transformed to a 0 to 100 scale. Higher scores indicate better functioning.

Three summary scores can be calculated: Total Scale Score (36 items); Parent HrQoL Summary Score (20 items); Family Functioning Score (8 items).

The newly developed QUALIFY questionnaire will assess disease-specific HrQoL of young people living wiht cystinosis.

Higher scores will indicate better HrQoL.