Patient-Reported Complications, Symptoms, and Experiences of Living With X-Linked Hypophosphatemia Across the Life-Course

Health-related quality of life of children with X-linked hypophosphatemia in Germany

BACKGROUND

X-linked hypophosphatemia (XLH) is a rare inherited phosphate-wasting disorder associated with bone and dental complications. Health-related quality of life (HRQoL) is reduced in XLH patients on conventional treatment with phosphate supplements and active vitamin D, while information on patients treated with burosumab is rare.

METHODS

HRQoL was assessed in 63 pediatric XLH patients participating in a prospective, observational study and patient registry in Germany using the KIDSCREEN-52 survey instrument and standardized qualitative interviews.

RESULTS

The median age of the XLH patients was 13.2 years (interquartile range 10.6 - 14.6). At the time of the survey, 55 (87%) patients received burosumab and 8 (13%) conventional treatment. Forty-six patients (84%) currently being treated with burosumab previously received conventional treatment. Overall, HRQoL was average compared to German reference values (mean ± SD: self-report, 53.36 ± 6.47; caregivers' proxy, 51.33 ± 7.15) and even slightly above average in some dimensions, including physical, mental, and social well-being. In general, XLH patients rated their own HRQoL higher than their caregivers. In qualitative interviews, patients and caregivers reported that, compared with conventional therapy, treatment with burosumab reduced stress, bone pain, and fatigue, improved physical health, and increased social acceptance by peers and the school environment.

CONCLUSIONS

In this real-world study in pediatric XLH patients, HRQoL was average or even slightly above that of the general population, likely due to the fact that the vast majority of patients had their treatment modality switched from conventional treatment to burosumab resulting in improved physical health and well-being.

A patient-centred and multi-stakeholder co-designed observational prospective study protocol: Example of the adolescent experience of treatment for X-linked hypophosphataemia (XLH)

The importance of patient centricity and keeping the patient at the heart of research design is now well recognised within the healthcare community. The involvement of patient, caregiver and clinician representatives in the study design process may help researchers to achieve this goal and to ensure robust and meaningful data generation. Real-world data collection allows for a more flexible and patient-centred research approach for gaining important insights into the experience of disease and treatments, which is acutely relevant for rare diseases where knowledge about the disease is more likely to be limited. Here, we describe a practical example of a patient-centric, multi-stakeholder approach that led to the co-design of a prospective observational study investigating the lived experience of adolescents with the rare disease, X-linked hypophosphataemia. Specifically, we describe how the knowledge and expertise of a diverse research team, which included expert physicians, research and technology specialists, patients and caregivers, were applied in order to identify the relevant research questions and to ensure the robustness of the study design and its appropriateness to the population of interest within the context of the current clinical landscape. We also demonstrate how a structured patient engagement exercise was key to informing the selection of appropriate outcome measures, data sources, timing of data collection, and to assessing the feasibility and acceptability of the proposed data collection approach.

The International X-Linked Hypophosphatemia (XLH) Registry: first interim analysis of baseline demographic, genetic and clinical data

BACKGROUND

X-linked hypophosphatemia (XLH) is a rare, hereditary, progressive, renal phosphate-wasting disorder characterized by a pathological increase in FGF23 concentration and activity. Due to its rarity, diagnosis may be delayed, which can adversely affect outcomes. As a chronic disease resulting in progressive accumulation of musculoskeletal manifestations, it is important to understand the natural history of XLH over the patient's lifetime and the impact of drug treatments and other interventions. This multicentre, international patient registry (International XLH Registry) was established to address the paucity of these data. Here we present the findings of the first interim analysis of the registry.

RESULTS

The International XLH Registry was initiated in August 2017 and includes participants of all ages diagnosed with XLH, regardless of their treatment and management. At the database lock for this first interim analysis (29 March 2021), 579 participants had entered the registry before 30 November 2020 and are included in the analysis (360 children [62.2%], 217 adults [37.5%] and 2 whose ages were not recorded [0.3%]; 64.2% were female). Family history data were available for 319/345 (92.5%) children and 145/187 (77.5%) adults; 62.1% had biological parents affected by XLH. Genetic testing data were available for 341 (94.7%) children and 203 (93.5%) adults; 370/546 (67.8%) had genetic test results; 331/370 (89.5%) had a confirmed PHEX mutation. A notably longer time to diagnosis was observed in adults ≥ 50 years of age (mean [median] duration 9.4 [2.0] years) versus all adults (3.7 [0.1] years) and children (1.0 [0.2] years). Participants presented with normal weight, shorter length or height and elevated body mass index (approximately - 2 and + 2 Z-scores, respectively) versus the general population. Clinical histories were collected for 349 participants (239 children and 110 adults). General data trends for prevalence of bone, dental, renal and joint conditions in all participants were aligned with expectations for a typical population of people with XLH.

CONCLUSION

The data collected within the International XLH Registry, the largest XLH registry to date, provide substantial information to address the paucity of natural history data, starting with demographic, family history, genetic testing, diagnosis, auxology and baseline data on clinical presentation.

Transition of young adults with metabolic bone diseases to adult care

As more accurate diagnostic tools and targeted therapies become increasingly available for pediatric metabolic bone diseases, affected children have a better prognosis and significantly longer lifespan. With this potential for fulfilling lives as adults comes the need for dedicated transition and intentional care of these patients as adults. Much work has gone into improving the transitions of medically fragile children into adulthood, encompassing endocrinologic conditions like type 1 diabetes mellitus and congenital adrenal hyperplasia. However, there are gaps in the literature regarding similar guidance concerning metabolic bone conditions. This article intends to provide a brief review of research and guidelines for transitions of care more generally, followed by a more detailed treatment of bone disorders specifically. Considerations for such transitions include final adult height, fertility, fetal risk, heritability, and access to appropriately identified specialists. A nutrient-dense diet, optimal mobility, and adequate vitamin D stores are protective factors for these conditions. Primary bone disorders include hypophosphatasia, X-linked hypophosphatemic rickets, and osteogenesis imperfecta. Metabolic bone disease can also develop secondarily as a sequela of such diverse exposures as hypogonadism, a history of eating disorder, and cancer treatment. This article synthesizes research by experts of these specific disorders to describe what is known in this field of transition medicine for metabolic bone diseases as well as unanswered questions. The long-term objective is to develop and implement strategies for successful transitions for all patients affected by these various conditions.

"Your Life Turns Upside Down": A Qualitative Study of the Experiences of Parents with Children Diagnosed with Phelan-McDermid Syndrome

(1) Background: Parents of children with rare diseases experience great uncertainty and employ different strategies to care for their children and cope with the disease. The purpose of the present study was to describe the perspective of parents with children with Phelan McDermid Syndrome (PMS). (2) Methods: A non-probabilistic purposeful sampling was used to perform this qualitative descriptive study. Thirty-two parents with children with PMS were interviewed. In-depth interviews and research field notes were analyzed using an inductive thematic analysis. (3) Results: Four themes emerged from the data. "Understanding and accepting the disease" described how parents experienced their child's diagnosis and the lack of information. The second theme, called "Living day by day", highlighted the daily difficulties faced when caring for a child with PMS. The third theme, "Expectations versus reality", was based on the parents' expectations of parenthood and the reality they face. Expectations for the future are also included. Finally, "Pain and happiness" describes how parents alternate feelings of distress and suffering but also joy with what they learn from these experiences. (4) Conclusions: Health professionals can use these results to support parents.

Experiences surrounding the diagnostic process and care among parents of children diagnosed with Phelan-McDermid syndrome: A qualitative study

AIM

To explore the experience of parents of children diagnosed with Phelan-McDermid syndrome (PMS) with regard to the diagnostic process, treatment, and medical care.

METHOD

A qualitative descriptive study was conducted. Participants were recruited using non-probabilistic purposeful sampling. In total, 32 parents with children with PMS were included. In-depth interviews and researcher field notes were used. An inductive thematic analysis was performed.

RESULTS

Five themes were identified: (1) the 'diagnostic process' describes the diagnostic process and how it is communicated to the parents; (2) 'treatment and expectations' describes the expectations and hopes placed on future treatment; (3) 'family planning' describes how parents deal with genetic counselling when planning to have more children after a diagnosis of PMS; (4) 'the world of disability' describes the entry of parents into an environment of dependency and disability after the diagnosis; (5) 'family's financial situation' highlights the financial difficulties due to the high cost of therapies and daily care products.

INTERPRETATION

Our results provide insight on how a diagnosis of PMS and its consequences are experienced by parents of children with PMS. These results can be used by health professionals to help and support parents.

Orthopedic Complications and Management in Children with X-Linked Hypophosphatemia

X-linked hypophosphatemia is an inheritable disease of renal phosphate wasting that results in clinically manifestations associated with rickets or osteomalacia. The various symptoms in the skeletal system are well recognized, such as short stature; lower limb deformities; and bone, joint, or muscle pain, and it is often difficult to control these symptoms, despite the use of medication therapy in growing children. In addition, lower limb deformities can lead to degenerative osteoarthritis and dysfunction of lower limbs at the skeletal maturity. To prevent from future manifestation of those symptoms, orthopedic surgeries are applicable to growing patients with severe skeletal deformities or without response to conventional medication. Bone deformities are treated by acute or gradual corrective osteotomies and temporally hemiepiphysiodesis using guided growth method. The clinicians should choose the right procedure based on age, symptoms and state of deformities of the patient.

Health-related quality of life of X-linked hypophosphatemia in Spain

BACKGROUND

Health-related quality of life (HRQoL) of patients with X-linked hypophosphatemia (XLH) is lower than that of both the general population and the patients with other chronic diseases, mainly due to diagnostic delay, treatment difficulties, poor psychosocial support, and problems with social integration. Early diagnosis and optimal treatment are paramount to control the disease in patients with XLH, avoid complications, and maintain or improve their HRQoL. We, therefore, analyzed the HRQoL of pediatric and adult patients with XLH treated with conventional therapy in Spain.

RESULTS

We used several versions of the EuroQol-5 dimensions (EQ-5D) instrument according to the age of patients with XLH. Then we compared the HRQoL of patients to that of the general Spanish population. Children with XLH (n = 21) had moderate problems in walking about (61.9%), washing or dressing themselves (9.52%), and performing their usual activities (33.33%). They also felt moderate pain or discomfort (61.9%) and were moderately anxious or depressed (23.81%). Adults with XLH (n = 29) had lower HRQoL, with problems in walking (93%, with 3.45% unable to walk independently), some level of pain (86%, with 3.45% experiencing extreme pain), problems with their usual activities (80%) and self-care (> 50%), and reported symptoms of anxiety and/or depression (65%). There were important differences with the general Spanish population.

CONCLUSIONS

XLH impacts negatively on physical functioning and HRQoL of patients. In Spanish patients with XLH, the HRQoL was reduced despite conventional treatment, clearly indicating the need to improve the therapeutic approach to this disorder.

X-Linked Hypophosphatemia Transition and Team Management

X-linked hypophosphatemia (XLH) is the most common form of inherited disorders that are characterized by renal phosphate wasting, but it is a rare chronic disease. XLH presents in multisystemic organs, not only in childhood, but also in adulthood. Multidisciplinary team management is necessary for the care of patients with XLH. Although XLH has often been perceived as a childhood disease, recent studies have demonstrated that it is a long-term and progressive disease throughout adulthood. In the past 20 years, the importance of the transition from pediatric care to adult care for patient outcomes in adulthood in many pediatric onset diseases has been increasingly recognized. This review describes transitional care and team management for patients with XLH.

Whole Body, Whole Life, Whole Family: Patients’ Perspectives on X-Linked Hypophosphatemia

The rare genetic disorder X-linked hypophosphatemia (XLH) is often exclusively considered to impact children, and as such, adult patients with XLH may receive inadequate care because their symptoms are not associated with XLH. However, studies have shown that XLH has long-term adverse health consequences that continue throughout adulthood requiring comprehensive lifelong care. Indeed, XLH impacts patients’ whole body, whole life, and whole family. XLH does not just affect the bones; symptoms are chronic and progressive, worsening throughout adulthood, and the burden of XLH overflows into the lives of patients’ family, friends, peers, and colleagues. To ensure early recognition, comprehensive care, and adequate management of XLH, there are key steps that clinicians can incorporate into their daily practice. These include education, a multidisciplinary approach, open communication, and support. Clinician education on rare disorders such as XLH is critical, and healthcare professionals (HCPs) should ensure that patients and their caregivers have access to XLH-related information. As a whole-body disorder, XLH requires a coordinated approach to treatment across specialties. Frequent open communication among members of the healthcare team is needed to increase HCPs’ knowledge about XLH, and open communication must extend to the patient as well to ensure the patient’s concerns and needs are addressed and treatment tailored to their specific individual needs. Multiple networks of support, including social and psychological support, should be offered to patients and their families. A basic understanding that XLH affects patients’ whole bodies, whole lives, and whole families is the first step toward accomplishing improved patient care.

Clinical practice guidelines for paediatric X-linked hypophosphataemia in the era of burosumab

X-linked hypophosphataemia (XLH), the most common inherited form of rickets, is caused by a PHEX gene mutation that leads to excessive serum levels of fibroblast growth factor 23 (FGF23). This leads to clinical manifestations such as rickets, osteomalacia, pain, lower limb deformity and overall diminished quality of life. The overarching aims in the management of children with XLH are to improve quality of life by reducing overall burden of disease, optimise an individual's participation in daily activities and promote normal physical and psychological development. Burosumab, a monoclonal antibody targeting FGF23, has been shown to improve biochemistry, pain, function and radiological features of rickets in children with XLH and has transformed management of XLH around the world. Burosumab has been recently approved for clinical use in children with XLH in Australia. This manuscript outlines a clinical practice guideline for the use of burosumab in children with XLH to assist local clinicians, encourage consistency of management across Australia and suggest future directions for management and research. This guideline also strongly advocates for all patients with XLH to have multidisciplinary team involvement to ensure optimal care outcomes and highlights the need to consider other aspects of care for XLH in the era of burosumab, including transition to adult care and the effective coordination of care between local health-care providers and specialist services.