X-Linked HypophosphatemiaNCT05181839
A Study to Describe the Lived Experience of XLH for Adolescents at End of Skeletal Growth
An observational study of X-Linked Hypophosphatemia, run by Kyowa Kirin Pharmaceutical Development Ltd at 14 sites in 5 countries.
Trial summary
An observational, prospective, mixed-methods study involving the integration of quantitative and qualitative data exploring the lived experience of burosumab-treated adolescents with XLH at the end of skeletal growth. Read more about this study
- Who is it for?
- Ages 12 to 17 years
- Conditions the study is for
- X-Linked Hypophosphatemia
- What is being tested?
- Burosumab
- How many people
- 25 participants
- Where
- 14 sitesin 5 countries
- Study dates
- 24 Nov 2021to 22 May 2024
- How long will I take part?
- 52 Weeks
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 12 to 17 years
- All sexes
- No healthy volunteers
- Child
Study population: The population for this study is adolescents with XLH approaching end of skeletal growth, who are being treated with burosumab for at least 12 months as part of routine clinical care at specialist paediatric centres within the UK, France, Germany, Spain and the Netherlands.
Who may be able to join
- Confirmed diagnosis of XLH (documented diagnosis of XLH in medical records, and evidence of at least one of the following: hypophosphataemia and/or impaired phosphate reabsorption due to elevated FGF23; PHEX mutation).
- Aged 12 to 17 years at start of study.
- Has open growth plates at enrolment and is estimated by their treating clinician to reach end of skeletal growth within the next 26 weeks (based on clinician's judgement in accordance with their normal approach used in routine practice).
- Has been receiving treatment with burosumab for at least study le (52 weeks).
- Provides informed consent to take part in the study (or provides assent, and carer provides consent, where applicable in accordance with specific country regulations).
- Carer Inclusion Criteria:
- A main carer of a study participant (i.e. a parent or guardian who provides day-today support or care for the adolescent with XLH who is taking part in this study).
- Provides informed consent to take part in the study (for self and/or on behalf of eligible adolescent, where applicable in accordance with specific country regulations).
Who cannot join
- Unwilling and unable to participate in all aspects of the study (i.e. interviews, app, EQ- 5D-Y, wearable data collection) and /or does not agree to the collection of data from medical records.
- Missed two or more injections of burosumab in the past 6 months.
- Is planned to have any surgery during the study period.
Trial locations and contacts
14 sites in 5 countries.
14 sites in 5 countries
United Kingdom5 sites
Birmingham Women's and Children's Hospital
Birmingham
Bristol Royal
Bristol
Alder Hey Children's Hospital
Liverpool
Great Ormond Street Hospital
London
Royal Manchester Childrens Hospital
Manchester, Greater Manchester, M13 9WL
Spain4 sites
Hospital Saint Joan de Deu
Barcelona, Catalona, 08907
Hospital Universitari Vall d'Hebron
Barcelona, Catalonia, 08035
Hospital General Universitario Santa Lucía
Cartagena, Murcia, 30202
Hospital Universitario Virgen a de las Nieves
Granada, Granada, 18014
France3 sites
Centre Hospitalier Universitair de Lille
Lille
Hospices Civils De Lyon
Lyon
APHP Paris - Assistance Publique Hopitaux de Paris
Paris
Germany1 site
Charité - Universitätsmedizin Berlin
Berlin, State of Berlin, 10117
Netherlands1 site
University Medical Center Groningen - Beatrix Children's Hospital
Groningen
About this study
Official title: An Observational, Prospective, European, Multicentre, Mixed Methods Study to Describe the Lived Experience of X-Linked Hypophosphatemia (XLH) for Adolescents at End of Skeletal Growth
An observational, prospective, mixed-methods study involving the integration of quantitative and qualitative data exploring the lived experience of burosumab-treated adolescents with XLH at the end of skeletal growth.
Read the detailed description
This an observational, prospective, European, multicentre, mixed methods study that will involve the integration of quantitative and qualitative data exploring the lived experience of burosumab-treated adolescents with XLH at the end of skeletal growth. The study will involve two observation periods around the confirmed date of end of skeletal growth (index date)
The purpose of this study is to describe the lived experience of XLH for adolescents who are being treated with burosumab at the end of skeletal growth, with a focus on adolescent reported symptoms, activity duration and intensity, and wider burden, and to describe change over time for those who continue and discontinue burosumab at the end of skeletal growth. The study will also explore the experiences of carers at the time the adolescent reaches the end of skeletal growth.
The key objectives of this study are to:
- Describe the lived experience of adolescents with XLH who are being treated with burosumab within the 12 weeks prior to reaching the end of skeletal growth.
- Describe the lived experience of adolescents with XLH during the 26 weeks immediately after the end of skeletal growth, overall and according to whether they continue or discontinue burosumab treatment.
- Describe within-person changes in the lived experience of adolescents with XLH after reaching end of skeletal growth, in relation to their own pre-end of skeletal growth period.
- Explore the supportive care needs and burden on carers at the time the adolescent with XLH reaches end of skeletal growth.
- Conditions
- X-Linked Hypophosphatemia
- Being tested
- Burosumab
- Medical subject headings
- Familial Hypophosphatemic Rickets
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
BurosumabDrug
To describe the lived experience of XLH for adolescents who are being treated with burosumab at the end of skeletal growth with a focus on adolescent-reported symptoms, activity duration and intensity, and wider burden, describing change over time for those who continue and discontinue burosumab after the end of skeletal growth.
What is being measured
The primary outcome is the main question the study is designed to answer.
Describe the lived experience of adolescents with XLH who are being treated with burosumab within the 12 weeks prior to reaching the end of skeletal growth.
Measured: 12 Weeks
Describe the lived experience of adolescents with XLH during the 26 weeks immediately after the end of skeletal growth, overall and according to whether they continue or discontinue burosumab treatment.
Measured: 26 weeks
Describe within-person changes in the lived experience of adolescents with XLH after reaching end of skeletal growth, in relation to their own pre-end of skeletal growth period.
Measured: Up to 52 weeks
Explore the supportive care needs and burden on carers at the time the adolescent with XLH reaches end of skeletal growth.
Measured: will be completed between weeks 21 and 25
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Jan 2022
- Study start24 Nov 2021
- Primary completion22 May 2024
- Study completion22 May 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (3)Papers the sponsor has linked to this study.
- Other trials for X-Linked HypophosphatemiaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 25 participants (actual)
- Target duration
- 52 Weeks
Sponsor and investigators
- Lead sponsor
- Kyowa Kirin Pharmaceutical Development Ltd
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05181839
- Sponsor's protocol ID
- 2020-70-EU-CRY
- Status last verified
- Sep 2024
- First submitted
- 15 Nov 2021
- Last updated
- 13 Jul 2026
- Results posted
- No
- Data monitoring committee
- No
- Individual data sharing
- No
Publications
Saraff V, Boot AM, Linglart A, Semler O, Harvengt P, Williams A, Bailey KMA, Glen F, Davies EH, Wood S, Greentree S, Rylands AJ. A patient-centred and multi-stakeholder co-designed observational prospective study protocol: Example of the adolescent experience of treatment for X-linked hypophosphataemia (XLH). PLoS One. 2024 Jan 19;19(1):e0295080. doi: 10.1371/journal.pone.0295080. eCollection 2024.
PubMed 38241270Saraff V, Sancho PA, Bacchetta J, Boot AM, Burren C, Chinoy A, Dharmaraj P, Llorente MAG, Rodriguez JDG, Gueorguieva I, Davies EH, Hayes W, Komarzynski S, Duro HR, Rylands AJ, Sandilands K, Williams A, Hardie E, Ishii H, Schnabel D, Selveindran SM, Linglart A. The lived experience of adolescents with X-linked hypophosphataemia treated with burosumab at end of skeletal growth: a mixed-methods analysis. PLoS One. 2026 Mar 20;21(3):e0344902. doi: 10.1371/journal.pone.0344902. eCollection 2026.
PubMed 41860923Saraff V, Arango-Sancho P, Bacchetta J, Boot AM, Burren CP, Chinoy A, Dharmaraj P, Gomez Llorente MA, Gonzalez Rodriguez JD, Gueorguieva I, Hayes W, Schnabel D, Duro HR, Davies EH, Komarzynski S, Rylands AJ, Sandilands K, Ishii H, Williams A, Selveindran S, Barlassina A, Bowden A, Linglart A. Adolescents' experience of living with X-linked hypophosphataemia (XLH): a mixed-methods analysis of those who continued and discontinued burosumab treatment after end of skeletal growth. Orphanet J Rare Dis. 2026 Feb 3;21(1):107. doi: 10.1186/s13023-026-04244-2.
PubMed 41634723
Study at a glance
From the registry record, last updated by the sponsor on 13 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- An Observational, Prospective, European, Multicentre, Mixed Methods Study to Describe the Lived Experience of X-Linked Hypophosphatemia (XLH) for Adolescents at End of Skeletal Growth
- ClinicalTrials.gov ID
- NCT05181839
- Acronym / sponsor ID
- 2020-70-EU-CRY
- Conditions
- X-Linked Hypophosphatemia
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 25 participants (actual)
- Lead sponsor
- Kyowa Kirin Pharmaceutical Development LtdIndustry (pharma, biotech, devices)
- Study start
- 24 Nov 2021 (actual)
- Primary completion
- 22 May 2024 (actual)
- Study completion
- 22 May 2024 (actual)
- First posted
- 6 Jan 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
An observational, prospective, mixed-methods study involving the integration of quantitative and qualitative data exploring the lived experience of burosumab-treated adolescents with XLH at the end of skeletal growth.
Detailed description
This an observational, prospective, European, multicentre, mixed methods study that will involve the integration of quantitative and qualitative data exploring the lived experience of burosumab-treated adolescents with XLH at the end of skeletal growth. The study will involve two observation periods around the confirmed date of end of skeletal growth (index date)
The purpose of this study is to describe the lived experience of XLH for adolescents who are being treated with burosumab at the end of skeletal growth, with a focus on adolescent reported symptoms, activity duration and intensity, and wider burden, and to describe change over time for those who continue and discontinue burosumab at the end of skeletal growth. The study will also explore the experiences of carers at the time the adolescent reaches the end of skeletal growth.
The key objectives of this study are to:
- Describe the lived experience of adolescents with XLH who are being treated with burosumab within the 12 weeks prior to reaching the end of skeletal growth.
- Describe the lived experience of adolescents with XLH during the 26 weeks immediately after the end of skeletal growth, overall and according to whether they continue or discontinue burosumab treatment.
- Describe within-person changes in the lived experience of adolescents with XLH after reaching end of skeletal growth, in relation to their own pre-end of skeletal growth period.
- Explore the supportive care needs and burden on carers at the time the adolescent with XLH reaches end of skeletal growth.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Target follow-up
- 52 Weeks
Who may qualify
- Ages
- 12 to 17 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child
- Study population
- The population for this study is adolescents with XLH approaching end of skeletal growth, who are being treated with burosumab for at least 12 months as part of routine clinical care at specialist paediatric centres within the UK, France, Germany, Spain and the Netherlands.
Key inclusion criteria (8 listed)
- Confirmed diagnosis of XLH (documented diagnosis of XLH in medical records, and evidence of at least one of the following: hypophosphataemia and/or impaired phosphate reabsorption due to elevated FGF23; PHEX mutation).
- Aged 12 to 17 years at start of study.
- Has open growth plates at enrolment and is estimated by their treating clinician to reach end of skeletal growth within the next 26 weeks (based on clinician's judgement in accordance with their normal approach used in routine practice).
- Has been receiving treatment with burosumab for at least study le (52 weeks).
- Provides informed consent to take part in the study (or provides assent, and carer provides consent, where applicable in accordance with specific country regulations).
Key exclusion criteria (3 listed)
- Unwilling and unable to participate in all aspects of the study (i.e. interviews, app, EQ- 5D-Y, wearable data collection) and /or does not agree to the collection of data from medical records.
- Missed two or more injections of burosumab in the past 6 months.
- Is planned to have any surgery during the study period.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| BurosumabTo describe the lived experience of XLH for adolescents who are being treated with burosumab at the end of skeletal growth with a focus on adolescent-reported symptoms, activity duration and intensity, and wider burden, describing change over time for those who continue and discontinue burosumab after the end of skeletal growth. | Drug | – |
Primary outcome
Describe the lived experience of adolescents with XLH who are being treated with burosumab within the 12 weeks prior to reaching the end of skeletal growth.
Time frame: 12 Weeks
Describe the lived experience of adolescents with XLH during the 26 weeks immediately after the end of skeletal growth, overall and according to whether they continue or discontinue burosumab treatment.
Time frame: 26 weeks
Describe within-person changes in the lived experience of adolescents with XLH after reaching end of skeletal growth, in relation to their own pre-end of skeletal growth period.
Time frame: Up to 52 weeks
Explore the supportive care needs and burden on carers at the time the adolescent with XLH reaches end of skeletal growth.
Time frame: will be completed between weeks 21 and 25
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 13 Jul 2026.
- Background: PubMed 38241270Saraff V, Boot AM, Linglart A, Semler O, Harvengt P, Williams A, Bailey KMA, Glen F, Davies EH, Wood S, Greentree S, Rylands AJ. A patient-centred and multi-stakeholder co-designed observational prospective study protocol: Example of the adolescent experience of treatment for X-linked hypophosphataemia (XLH). PLoS One. 2024 Jan 19;19(1):e0295080. doi: 10.1371/journal.pone.0295080. eCollection 2024.
- Results publication: PubMed 41860923Saraff V, Sancho PA, Bacchetta J, Boot AM, Burren C, Chinoy A, Dharmaraj P, Llorente MAG, Rodriguez JDG, Gueorguieva I, Davies EH, Hayes W, Komarzynski S, Duro HR, Rylands AJ, Sandilands K, Williams A, Hardie E, Ishii H, Schnabel D, Selveindran SM, Linglart A. The lived experience of adolescents with X-linked hypophosphataemia treated with burosumab at end of skeletal growth: a mixed-methods analysis. PLoS One. 2026 Mar 20;21(3):e0344902. doi: 10.1371/journal.pone.0344902. eCollection 2026.
- Results publication: PubMed 41634723Saraff V, Arango-Sancho P, Bacchetta J, Boot AM, Burren CP, Chinoy A, Dharmaraj P, Gomez Llorente MA, Gonzalez Rodriguez JD, Gueorguieva I, Hayes W, Schnabel D, Duro HR, Davies EH, Komarzynski S, Rylands AJ, Sandilands K, Ishii H, Williams A, Selveindran S, Barlassina A, Bowden A, Linglart A. Adolescents' experience of living with X-linked hypophosphataemia (XLH): a mixed-methods analysis of those who continued and discontinued burosumab treatment after end of skeletal growth. Orphanet J Rare Dis. 2026 Feb 3;21(1):107. doi: 10.1186/s13023-026-04244-2.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
14 sites in 5 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of X-Linked Hypophosphatemia, run by Kyowa Kirin Pharmaceutical Development Ltd at 14 sites in 5 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 8 inclusion and 3 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 13 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 14 sites in United Kingdom, Spain, France, Germany, Netherlands. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Describe the lived experience of adolescents with XLH who are being treated with burosumab within the 12 weeks prior to reaching the end of skeletal growth. (time frame: 12 Weeks). The study lists 4 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05181839, which also lists 3 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 13 Jul 2026; AzTrials last refreshed its copy on 7 Nov 2026.