Natural history of urine and plasma oxalate in children with primary hyperoxaluria type 1.

BACKGROUND: Primary hyperoxaluria type 1 (PH1) is a rare, severe genetic disease causing increased hepatic oxalate production resulting in urinary stone disease, nephrocalcinosis, and often progressive chronic kidney disease. Little is known about the natural history of urine and plasma oxalate values over time in children with PH1. METHODS: For this retrospective observational study, we analyzed data from genetically confirmed PH1 patients enrolled in the Rare Kidney Stone Consortium PH Registry between 2003 and 2018 who had at least 2 measurements before age 18 years of urine oxalate-to-creatinine ratio (Uox:cr), 24-h urine oxalate excretion normalized to body surface area (24-h Uox), or plasma oxalate concentration (Pox). We compared values among 3 groups: homozygous G170R, heterozygous G170R, and non-G170R AGXT variants both before and after initiating pyridoxine (B6). RESULTS: Of 403 patients with PH1 in the registry, 83 met the inclusion criteria. Uox:cr decreased rapidly over the first 5 years of life. Both before and after B6 initiation, patients with non-G170R had the highest Uox:cr, 24-h Uox, and Pox. Patients with heterozygous G170R had similar Uox:cr to homozygous G170R prior to B6. Patients with homozygous G170R had the lowest 24-h Uox and Uox:cr after B6. Urinary oxalate excretion and Pox tend to decrease over time during childhood. eGFR over time was not different among groups. CONCLUSIONS: Children with PH1 under 5 years old have relatively higher urinary oxalate excretion which may put them at greater risk for nephrocalcinosis and kidney failure than older PH1 patients. Those with homozygous G170R variants may have milder disease. A higher resolution version of the Graphical abstract is available as Supplementary information.

Qualitative assessment of the patient experience of primary hyperoxaluria type 1: an observational study.

BACKGROUND: Without effective intervention, primary hyperoxaluria type 1 (PH1) causes oxalate-induced kidney damage, leading to end-stage kidney disease and serious complications throughout the body. Although PH1 carries a heavy burden that impacts quality of life, literature on the experiences of those living with PH1 and caring for patients with PH1 is limited. This study aimed to describe the diagnostic journey in PH1 and characterize patients' and caregivers' self-reported experiences throughout the disease course. METHODS: This was an observational study involving in-depth, semi-structured telephone interviews. Dominant trends were assessed using constant comparative analysis to identify themes in interviewees' descriptions of their experiences. Individuals aged ≥ 12 years and caregivers of children aged 6-17 years with genetically confirmed PH1 were eligible. Informed consent/assent and ability to read and speak English were required. RESULTS: Interviewees (16 patients, 12 caregivers) reported a prolonged diagnostic journey due to low disease awareness, among other factors. Upon diagnosis, PH1 was frequently symptomatic, typically involving kidney stone-related symptoms but also potentially symptoms arising beyond the kidneys. PH1 most commonly led to worry and social impairment in adolescents, impaired physical function in adults, and a range of impacts on caregivers. In late-stage disease, dialysis was the most burdensome aspect of living with PH1 (due to time requirements, limitations from living with a catheter, etc.), and this burden was exacerbated by the COVID-19 pandemic. Benefits desired from PH1 management included reductions in laboratory measures of oxalate burden, kidney stone and urination frequency, and oxalate-related skin ulcers. CONCLUSIONS: PH1 greatly impacts patients' and caregivers' lives, primarily due to burdensome disease manifestations and associated emotional, physical, and practical impacts, as well as disease management challenges - particularly those related to dialysis in late-stage disease.

Impact of Vutrisiran on Quality of Life and Physical Function in Patients with Hereditary Transthyretin-Mediated Amyloidosis with Polyneuropathy.

INTRODUCTION: Hereditary transthyretin (ATTRv; v for variant) amyloidosis, also known as hATTR amyloidosis, is a progressive and fatal disease associated with rapid deterioration of physical function and patients' quality of life (QOL). Vutrisiran, a subcutaneously administered RNA interference (RNAi) therapeutic that reduces hepatic production of transthyretin, was assessed in patients with ATTRv amyloidosis with polyneuropathy in the pivotal HELIOS-A study. METHODS: The phase 3 open-label HELIOS-A study investigated the efficacy and safety of vutrisiran in patients with ATTRv amyloidosis with polyneuropathy, compared with an external placebo group from the APOLLO study of the RNAi therapeutic patisiran. Measures of QOL and physical function were assessed. RESULTS: At month 18, vutrisiran improved Norfolk Quality of Life-Diabetic Neuropathy (Norfolk QOL-DN) total score (least squares mean difference [LSMD] in change from baseline [CFB]: -21.0; p = 1.84 × 10-10) and Norfolk QOL-DN domain scores, compared with external placebo. This benefit relative to external placebo was evident across all baseline polyneuropathy disability (PND) scores and most pronounced in patients with baseline PND scores I-II. Compared with external placebo, vutrisiran also demonstrated benefit in EuroQoL-Visual Analog Scale (EQ-VAS) score (LSMD in CFB: 13.7; nominal p = 2.21 × 10-7), 10-m walk test (LSMD in CFB: 0.239 m/s; p = 1.21 × 10-7), Rasch-built Overall Disability Score (LSMD in CFB: 8.4; p = 3.54 × 10-15), and modified body mass index (mBMI) (LSMD in CFB: 140.7; p = 4.16 × 10-15) at month 18. Overall, Norfolk QOL-DN, EQ-VAS, and mBMI improved from pretreatment baseline with vutrisiran, whereas all measures worsened from baseline in the external placebo group. At month 18, Karnofsky Performance Status was stable/improved from baseline in 58.2/13.1% with vutrisiran versus 34.7/8.1% with external placebo. CONCLUSION: Vutrisiran treatment provided significant clinical benefits in multiple measures of QOL and physical function in patients with ATTRv amyloidosis with polyneuropathy. Benefits were most pronounced in patients with earlier-stage disease, highlighting the importance of early diagnosis and treatment. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov: NCT03759379.

Indirect treatment comparison (ITC) of the efficacy of vutrisiran and tafamidis for hereditary transthyretin-mediated amyloidosis with polyneuropathy.

BACKGROUND: Vutrisiran and tafamidis are approved therapies for treating hereditary transthyretin-mediated (ATTRv/hATTR) amyloidosis with polyneuropathy, a rapidly progressive and fatal disease. To assist healthcare decision-makers, an indirect treatment comparison (ITC) was undertaken to explore the comparative efficacy of vutrisiran and tafamidis. RESEARCH DESIGN AND METHODS: Individual patient data (vutrisiran vs. placebo) and published results (tafamidis vs. placebo) from phase 3 randomized controlled trials were used in a Bucher analysis to assess differences in treatment effects between vutrisiran and tafamidis on: Neuropathy Impairment Score-Lower Limbs (NIS-LL), Norfolk Quality of Life-Diabetic Neuropathy (Norfolk QOL-DN) score, NIS-LL Response, and modified Body Mass Index (mBMI). RESULTS: Greater treatment effects were observed at 18 months with vutrisiran vs. tafamidis for all endpoints, with statistically significant improvements in polyneuropathy (relative mean change in NIS-LL: -5.3 [95% confidence interval (CI): -9.4, -1.2; p = 0.011]), health-related quality of life (HRQOL, relative mean change in Norfolk QOL-DN: -18.3 [95% CI: -28.6, -8.0; p < 0.001]), and nutritional status (relative mean change in mBMI: 63.9 [95% CI: 10.1, 117.7; p = 0.020]). CONCLUSIONS: This analysis suggests vutrisiran has greater efficacy on multiple measures of polyneuropathy impairment and HRQOL compared to tafamidis in patients with ATTRv amyloidosis with polyneuropathy.

Hereditary transthyretin-mediated (ATTRv/hATTR) amyloidosis is a rare genetic disease that runs in families, affecting about 50,000 people worldwide. This condition results in abnormal protein deposits building up, causing damage to multiple nerves (polyneuropathy) and other organs, which can shorten lifespan and have other harmful effects. Polyneuropathy symptoms include weakness, numbness, pain, dizziness, and diarrhea. Over time, everyday activities become more difficult as patients become increasingly disabled and dependent on others. Several treatments have been approved for the polyneuropathy of ATTRv amyloidosis. Many of these work in different ways to impact the disease process. An indirect treatment comparison is a well-established statistical method used by healthcare decision-makers to compare treatments when head-to-head trials are unavailable. Indirect treatment comparisons using a common approach, the Bucher method, yield similar conclusions to head-to-head studies over 90% of the time. This method was used to compare clinical trial data for tafamidis and vutrisiran, two approved treatments for ATTRv amyloidosis with polyneuropathy. The findings show that vutrisiran is more effective than tafamidis at addressing the polyneuropathy of ATTRv amyloidosis as measured by changes to sensory or motor nervous system functioning and nutritional status. Also, vutrisiran showed greater maintenance of health-related quality of life compared to tafamidis. The expected benefits of vutrisiran over tafamidis are large enough to be noticeable and clinically meaningful to a patient or clinician. This highlights the potential advantages of vutrisiran compared to tafamidis with regard to preservation of physical function and quality of life when treating ATTRv amyloidosis with polyneuropathy.

Estimating health state utilities in primary hyperoxaluria type 1: a valuation study.

AIMS: Quantitative data on health state utilities in primary hyperoxaluria type 1 (PH1) are lacking. This study was conducted to estimate utility values in PH1 using 3 standard valuation techniques. MATERIALS AND METHODS: Health state vignettes were developed with input from expert clinicians to describe different stages of chronic kidney disease (CKD) within the setting of PH1, along with a post-combined liver and kidney transplant (CLKT) health state ≥12 months following transplantation. The utility associated with living in each PH1 health state, as described by the vignettes, was evaluated by members of the UK general public using standard utility assessment techniques, including EQ-5D-5L, Visual Analog Scale, and Time Trade-Off. RESULTS: A similar pattern across the three valuation methods was observed. Utility values were roughly constant from CKD stage 1-3b and then dropped sharply from these states to CKD stage 4. Decreases in utility in the later stages of CKD (stages 4-5) were followed by a recovery in quality of life in the post-CLKT health state. LIMITATIONS: Vignettes may not fully capture the burden of living with PH1. CONCLUSIONS: This study serves as an informative source of data on how the burden of PH1 varies across disease stages of CKD and post-CLKT in patients with PH1. The study findings highlight the unique clinical features of PH1 compared with non-PH1-related CKD, such as the need for earlier and more intensive hemodialysis, the risk of systemic oxalosis, and the potential need for CLKT (as opposed to kidney-only transplant). The impact of PH1 on health-related quality of life, which worsens once hemodialysis is required and systemic disease manifestations occur, is captured in this study using quantitative health state utilities. These data provide an understanding of the impact of PH1 on health-related quality of life and will facilitate health economic evaluation of future treatments.

Primary hyperoxaluria type 1 (PH1) is a rare genetic disease in which the body produces too much oxalate, leading to kidney damage. Over time it can affect other organs such as the bones, the heart, and the eyes. As kidney damage progresses, patients with PH1 eventually need to receive kidney dialysis. New and emerging treatments aim to reduce oxalate production. To assess the economic value of treatments, data are needed on the quality of life of patients in different stages of PH1. This study collected these data using standard valuation methods. First, we developed written descriptions of different stages of PH1 using expert clinical input and information from published studies. Then, members of the UK general public valued the descriptions in three ways: via a survey called EQ-5D-5L (which asks participants about their mobility, self-care, usual activities, pain/discomfort, and anxiety/depression), via EQ-VAS (a visual scale, resembling a ruler, used to rate quality of life), and via time trade-off (in which participants were asked how many years of perfect health they would give up to avoid living in each disease stage described). The results show that PH1 is likely to have a considerable impact on patients' quality of life, especially in advanced stages, when dialysis is needed and multiple organs are impacted. The study provides measurable estimates of quality of life in people with PH1, which helps healthcare providers, policy makers, and payers understand the disease burden of PH1. The results can also be used in economic evaluation of new treatments.

Primary Hyperoxaluria Type 1 Disease Manifestations and Healthcare Utilization: A Multi-Country, Online, Chart Review Study.

Background: Primary hyperoxaluria type 1 (PH1) is a rare genetic disease that can result in irreversible damage to the kidneys and, eventually, extrarenal organs. While kidney failure is a known consequence of PH1, few studies to date have characterized clinical consequences of PH1 prior to kidney failure, and data on healthcare resource use outcomes across different stages of disease severity in PH1 are also limited. To help fill this knowledge gap, this study characterized the clinical and healthcare resource use (HRU) burden in patients with PH1 with varying stages of kidney disease. Methods: Nephrologists in the United States, Canada, United Kingdom, France, Germany, and Italy abstracted chart data from patients with PH1 under their care via an online questionnaire. Eligible patients had confirmed PH1 and ≥2 office visits from 2016 to 2019. Results: A total of 120 patients were analyzed (median age at diagnosis, 17.4 years old, median age at index 19.5 years old, median eGFR at index 45 ml/min/1.73 m2; median follow-up 1.7 years). During follow-up, the most common PH1 manifestations were kidney stones and urinary tract infections (UTIs, both 56.8%), and the most common symptoms were fatigue/weakness (71.7%) and pain (64.6%). With regard to HRU during follow-up, 37.4% required lithotripsy, 31.3% required ureteroscopy, and 9.6% required nephrolithotomy. PH1-related hospitalizations and emergency/urgent care visits were noted for 84.0 and 81.6% of patients, respectively. Conclusions: The current study demonstrated that patients with PH1 across various stages of kidney disease exhibited a substantial clinical burden, including kidney stones, UTIs, fatigue/weakness, and pain, and required frequent HRU, including kidney stone procedures, hospitalizations, and emergency visits. These findings highlight the significant morbidity and HRU burden in patients with PH1.