Research Project

Project Title:

QUALIFY- Development of a patient-reported outcome to measure the health-related quality of life of children and adolescents with cystinosis

Project Type:

Clinical Trial, Enrolment ongoing

Disease group(s):


Project Summary:

Cystinosis is a rare congenital, inherited metabolic disorder that results in the accumulation of cystine in the cells of many organs of the body. In the infantile nephropathic form of the disease, the kidney is initially affected by a loss of function, which progresses if left untreated, culminating in terminal renal failure by early school age. With the prolonged survival of patients due to medication and renal replacement therapy, further loss of function may occur as the disease progresses, especially in the eyes, muscles, endocrine organs and central nervous system.
The transition from pediatric and adolescent medicine to adult medicine has become a central issue due to extended survival.

The quality of life of children with cystinosis has been a poorly studied topic. The results of the studies available to date show that the young patients and their families report a reduced quality of life and, in some cases, behavioral problems.
To date, there are no specific patient reported outcome measures (PROMs) to assess the quality of life of patients with cystinosis. The aim of this study is to develop a PROM for this target group in several languages (German, English, Spanish, French) from different countries (Germany, United States, Spain, France). The focus of the PROM here is on quality of life and will be developed for children, adolescents and young adults aged 0 to 26 years.

First, a literature review will be conducted to identify relevant quality of life topics for the focus interviews (Phase 1). Development of the cystinosis-specific PROM will include three phases with patient recruitment: (1) focus interviews, (2) pilot-test and cognitive debriefing, and (3) field and re-test. In all study phases, patient recruitment follows these inclusion criteria: Children, adolescents and young adults aged 8-26 years and at least one parent for patients aged 8-18 years and only parents of affected children aged 0-7 years; confirmed diagnosis of cystinosis in the child; sufficient language skills; written informed consent.
Stratification by age group is necessary for successful measurement and interpretation of HrQoL measures. Stratification by age groups includes children, adolescents, and young adults aged 8-12, 13-18, 19-26 years for a self-reported version and children and adolescents aged 0-4, 5-7, 8-12, 13-18 years for a parent-reported version.

The final product will be a psychometrically validated, easy-to-use, and conceptually appropriate quality of life instrument available in German, English, Spanish, and French for use in research and patient care.

Lead principal investigator(s):

J Quittmann, Rosenheim
S Witt, Rosenheim
S Suck , Rosenheim


Katharina Hohenfellner, Rosenheim
Aude Servais, Paris
Gema Ariceta, Barcelona

Project Period:

10/2022   -   12/2025


Non-profit foundation

Project web page:

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