Hospitalizations for mitochondrial disease across the lifespan in the U.S

A population-based cohort study of mitochondrial disease and mental health conditions in Ontario, Canada

BACKGROUND

Mitochondrial disease has been linked to mental health disorder in clinical cohorts and post-mortem studies. However, a lack of population-level studies examining the relationship between mitochondrial disease and mental health has resulted in an evidence gap and creates a challenge for identifying and addressing care needs for the mitochondrial disease population. Using multiple linked population health databases in a single-payer health system that covers the full population, this study aimed to investigate the prevalence of mood disorders and other mental health conditions in patients with mitochondrial disease and to examine the joint impact of mitochondrial disease and mental health conditions on healthcare use and health system costs. To contextualize these findings, a clinical comparator cohort of multiple sclerosis (MS) patients was analyzed.

RESULTS

Overall, co-prevalent mental health conditions are common in the mitochondrial population. Double the proportion of patients in the mitochondrial disease cohort had a co-prevalent mental health illness as compared to the MS population (18% vs 9%). Healthcare utilization was highest among patients with co-prevalent mitochondrial disease and mental illness, with 49% hospitalized within 1 year prior to cohort entry (compared to 12% of MS patients with no mental health condition). Costs were likewise highest among mitochondrial disease patients with mental health conditions.

CONCLUSIONS

This study presents the first comprehensive, population-wide cohort study of mitochondrial disease and co-prevalent mental health conditions. Our findings demonstrate a high burden of mental health conditions among mitochondrial disease patients, with high associated health care needs. We also find that patients with concurrent mental illness and mitochondrial disease represent a high-burden, high-cost population in a single-payer health insurance setting.

Preliminary investigation on the economic cost of mitochondrial disease in Chinese children

BACKGROUND

The prevalence of mitochondrial diseases is increasing, leading to a significant economic burden on families and society. However, nationwide cost data on their effects on China's economy remain limited. This study aimed to investigate the economic cost of mitochondrial diseases in Chinese children, analyse the relevant influencing factors, and provide a foundation for strategies to reduce the healthcare burden.

METHODS

In this single-centre, cross-sectional study, an online questionnaire was randomly administered to paediatric patients diagnosed with mitochondrial diseases between January 2012 and January 2022. The questionnaire included questions regarding demographic data, clinical information, and expenditure-related costs. Multivariate analysis of economic cost was performed using a generalised linear gamma conjugate model (A1).

RESULTS

The responses to 102 questionnaires were analysed. The median direct economic cost incurred for the diagnosis of mitochondrial disease was $8,520.19, with direct medical and non-medical costs of $6,769.06 and $2,092.98, respectively, and an indirect cost of $3,162.93. Healthcare insurance covers 27.29% of direct medical expenses. Multivariate analysis showed that the economic cost of diagnosing mitochondrial diseases was significantly correlated with the year of disease onset (P < 0.001). The median annual economic cost for treatment and symptom management after diagnosis was $12,292.79, with direct medical and non-medical costs of $10,887.53 and $1,360.44, respectively, and an indirect cost of $5,442.21. Healthcare insurance covered only 15.16% of direct medical expenses. No significant differences were observed between the subgroups after diagnosis and the annual economic costs of treatment or symptom management.

CONCLUSION

The study findings indicated that the economic burden of both the diagnosis and treatment of patients with mitochondrial diseases was substantial. Increased emphasis should be placed on primary and secondary prevention strategies to further reduce the overall economic burden of rare genetic diseases, such as mitochondrial diseases.

Improving acute care for Primary Mitochondrial Disease: Development of a publicly available clinical care pathway

Primary mitochondrial diseases (PMD) are an increasingly recognized cause of multi-system organ dysfunction. Children frequently require acute care in an inpatient setting, though many hospitals do not have access to metabolic specialists. We developed a publicly available, evidenced-based clinical pathway utilizing expert consensus guidelines to guide the care of PMD patients during an emergency department visit and/or hospitalization. Utilization of the pathway may help improve triage time, clarify therapeutic options, and help initiate disease-specific screening.

Demographic characteristics, diagnostic challenges, treatment patterns, and caregiver burden of mitochondrial diseases: a retrospective cross-sectional study

BACKGROUND

This study aimed to explore the demographic characteristics, diagnostic challenges, treatment patterns, and caregiver burden of mitochondrial diseases.

METHODS

This retrospective cross-sectional study enrolled patients diagnosed with mitochondrial diseases from the Department of Neurology at Peking University First Hospital between January 2010 and December 2021. A questionnaire covering demographic characteristics, diagnostic dilemma, treatment, economic aspects, and caregiver stress was administered, and disability was assessed using the modified Rankin Scale (mRS).

RESULTS

A total of 183 patients (mean age: 16 (IQR: 12-25), 49.72% males) were enrolled, including 124 pediatric patients and 59 adult patients. MELAS (106. 57.92%) and Leigh syndrome (37, 20.22%) were predominant among the mitochondrial disease subtypes. Among them, 132 (72.13%) patients were initially misdiagnosed with other diseases, 58 (31.69%) patients visited 2 hospitals before confirmed as mitochondrial disease, and 39 (21.31%) patients visited 3 hospitals before confirmed as mitochondrial disease. Metabolic modifiers were the most common type of drugs used, including several dietary supplements such as L-carnitine (117, 63.93%), Coenzyme Q10 (102, 55.74%), idebenone (82, 44.81%), and vitamins (99, 54.10%) for proper mitochondrial function. Mothers are the primary caregivers for both children (36.29%) and adults (38.98%). The mRS score ranged from 0 to 5, 92.35% of the patients had different degrees of disability due to mitochondrial disease. The average monthly treatment cost was 3000 RMB for children and 3100 RMB for adults.

CONCLUSIONS

This study provided valuable insights into the characteristics and challenges of mitochondrial diseases, which underscores the need for improved awareness, diagnostic efficiency, and comprehensive support for patients and caregivers.

Clinical drivers of hospitalisation in patients with mitochondrial diseases

Background

Mitochondrial diseases in adults are generally chronic conditions with a wide spectrum of severity contributing to disease burden and healthcare resource utilisation. Data on healthcare resource utilisation in mitochondrial diseases are limited.

Objectives

We performed a retrospective longitudinal study to investigate the clinical drivers of hospitalisation in adult patients with mitochondrial diseases to better understand healthcare resource utilisation.

Methods

We recruited participants from our specialised Mitochondrial Disease Clinic in Sydney, Australia between September 2018 and December 2021. We performed a retrospective chart review for the period 2013-2022 considering emergency department (ED) and/or hospital admission notes, as well as discharge summaries. We used multiple linear regression models to examine the association between the type of presenting symptom(s) and duration of hospital stay and frequency of admissions, while adjusting for relevant covariates.

Results

Of the 99 patients considered, the duration of hospitalisation ranged from 0 to 116 days per participant and the number of admissions ranged from 0 to 21 per participant. Participants with one or more mitochondrial disease-associated admissions constituted 52% of the study cohort. 13% of the participants presented to the ED without requiring an admission and 35% never attended the ED or required a hospital admission during this period. Neurological (p<0.0001), gastroenterological (p=0.01) and symptoms categorised as 'other' (p<0.0001) were the main presentations driving the total number of days admitted to hospital. A statistically significant association was evident for the number of admissions and all types of presenting symptoms (p<0.0001).

Conclusion

There are variable reasons for hospitalisation in adults with mitochondrial diseases, with neurological and gastroenterological presentations being associated with prolonged and complex hospitalisation. A better understanding of clinical drivers such as these allows for better informed and well-coordinated management aimed at optimising healthcare resource utilisation.

Epitope-level profiling in children with mitochondrial disease reveals limitations in the antibacterial antibody repertoire

INTRODUCTION

Immunometabolic studies in mice have suggested the importance of oxidative phosphorylation (OXPHOS) in humoral immunity. However, there are important distinctions between murine and human immunity. Furthermore, translational studies on the role of OXPHOS in humoral immunity are nearly absent from the biomedical literature. Children with primary OXPHOS deficiency (i.e., mitochondrial disease, MtD), are an important patient population for demonstrating the functional effects of this bioenergetic defect on humoral immunity.

METHODS

To define whether OXPHOS deficiency extended to human B cells, we performed extracellular flux analysis on lymphoblastoid B cell lines from children with MtD and controls (N = 4/group). To expand the immune phenotype of B cell OXPHOS deficiency, we conducted a cross-sectional multiplex serology study of the antibacterial antibody repertoire in children with MtD (N = 16) and controls (N = 16) using phage display and immunoprecipitation sequencing (PhIPseq). The PhIPseq library contained >3000 peptides (i.e., epitopes) covering >40 genera and > 150 species of bacteria that infect humans.

RESULTS

B cell lymphoblastoid cell lines from children with MtD displayed depressed baseline oxygen consumption, ATP production and reserve capacity, indicating that OXPHOS deficiency extended to these key cells in humoral immunity. Characterization of the bacterial exposome revealed comparable bacterial species between the two groups, mostly Streptococcus and Staphylococcus. The most common species of bacteria was S. pneumoniae. By interrogating the antibacterial antibody repertoire, we found that children with MtD had less robust antibody fold changes to common epitopes. Furthermore, we also found that children with MtD failed to show a direct relationship between the number of bacterial epitopes recognized and age, unlike controls. OXPHOS deficiency extends to B cells in children with MtD, leading to limitations in the antibacterial antibody repertoire. Furthermore, the timing of bacterial exposures was asynchronous, suggesting different periods of increased exposure or susceptibility.

CONCLUSIONS

Overall, the antibacterial humoral response is distinctive in children with MtD, suggesting an important role for OXPHOS in B cell function.

Pathogenic BCS1L Mutation Resulting in Hypertrophic Cardiomyopathy: A Unique Presentation of Nuclear Mitochondrial Disease

A 21-year-old man with sensorineural hearing loss and glaucoma presented with severely limited exercise capacity since childhood. He was found to have biventricular concentric hypertrophy with greatest wall thickening at the posterior and lateral walls of the left ventricle apex (1.7 cm) and the free wall of the right ventricle (1.1 cm). There was no inducible left ventricular outflow tract obstruction. Metabolic testing revealed marked lactic aciduria (1,650.1 μmol/mmol creatinine) and plasma lactate (3.9 mmol/L). A sarcomeric hypertrophic cardiomyopathy gene panel was unremarkable, but mitochondrial gene analysis revealed a homozygous c.385G&gt;A (p.Gly129Arg) pathogenic mutation in the BCS1L gene. This gene is responsible for an assembly subunit of cytochrome complex III in the respiratory transport chain and is the rarest respiratory chain defect. This gene has not frequently been implicated in cardiomyopathy. Mitochondrial hypertrophic cardiomyopathy is more rare than hypertrophic cardiomyopathy resulting from sarcomeric mutations and is more likely to be symmetric, less frequently results in left ventricular outflow tract obstruction, and is more likely to progress to dilated cardiomyopathy. Evidence-based screening protocols have not been established; treatment follows guideline-directed medical therapy for congestive heart failure, including evaluation for heart transplantation. This report expands the phenotype of the BCS1L mutation and suggests that affected patients may need screening for underlying cardiomyopathy.

Individual and Family Determinants for Quality of Life in Parents of Children with Inborn Errors of Metabolism Requiring a Restricted Diet: A Multilevel Analysis Approach

OBJECTIVE

The objective of this study was to compare the quality of life (QoL) for parents of children with inborn errors of metabolism (IEMs) requiring a restricted diet with French population norms and investigate parental QoL determinants.

STUDY DESIGN

This cross-sectional study included mothers and/or fathers of children < 18 years of age affected by IEMs requiring a restricted diet (except phenylketonuria) from January 2015 to December 2017. Parents' QoL was assessed using the World Health Organization Quality of Life BREF questionnaire and compared with age- and sex-matched reference values from the French general population. Linear mixed models were used to examine the effects of demographic, socioeconomic, disease-related, and psychocognitive factors on parental QoL, according to a 2-level regression model considering individuals (parents) nested within families.

RESULTS

Of the 1156 parents invited to participate, 785 (68%) were included. Compared with the general population, parents of children with IEMs requiring a restricted diet reported a lower QoL in physical and social relationship domains but a higher QoL in the psychological domain. In the multivariate analysis, characteristics associated with poorer parental QoL included both parent-related factors (being a father, older age, more educated parent, nonworking parent, greater anxiety, seeking more social support, and using less positive thinking and problem-solving coping strategies) and family-related factors (disease complications, increased number of hospital medical providers, child's younger age, single-parent family, and lower family material wealth).

CONCLUSION

Parents of children with IEMs requiring a restricted diet reported poorer QoL in physical and social relationship domains than population norms. Psychocognitive factors, beyond disease-specific and family-related characteristics, were the most important determinants influencing parental QoL and may represent essential aspects for interventions.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov: NCT02552784.

Estimation of the Number of Patients With Mitochondrial Diseases: A Descriptive Study Using a Nationwide Database in Japan

BACKGROUND

To provide a better healthcare system for patients with mitochondrial diseases, it is important to understand the basic epidemiology of these conditions, including the number of patients affected. However, little information about them has appeared in Japan to date.

METHODS

To gather data of patients with mitochondrial diseases, we estimated the number of patients with mitochondrial diseases from April 2018 through March 2019 using a national Japanese health care claims database, the National Database (NDB). Further, we calculated the prevalence of patients, and sex ratio, age class, and geographical distribution.

RESULTS

From April 2018 through March 2019, the number of patients with mitochondrial diseases was 3,629, and the prevalence was 2.9 (95% confidence interval [CI], 2.8-3.0) per 100,000 general population. The ratio of females and males was 53 to 47, and the most frequent age class was 40-49 years old. Tokyo had the greatest number of patients with mitochondrial diseases, at 477, whereas Yamanashi had the fewest, at 13. Kagoshima had the highest prevalence of patients with mitochondrial diseases, 8.4 (95% CI, 7.1-10.0) per 100,000 population, whereas Yamanashi had the lowest, 1.6 (95% CI, 0.8-2.7).

CONCLUSION

The number of patients with mitochondrial diseases estimated by this study, 3,269, was more than double that indicated by the Japanese government. This result may imply that about half of all patients are overlooked for reasons such as low severity of illness, suggesting that the Japanese healthcare system needs to provide additional support for these patients.

Lactate metabolism is essential in early-onset mitochondrial myopathy

Myopathies secondary to mitochondrial electron transport chain (ETC) dysfunction can result in devastating disease. While the consequences of ETC defects have been extensively studied in culture, little in vivo data are available. Using a mouse model of severe, early-onset mitochondrial myopathy, we characterized the proteomic, transcriptomic, and metabolic characteristics of disease progression. Unexpectedly, ETC dysfunction in muscle results in reduced expression of glycolytic enzymes in our animal model and patient muscle biopsies. The decrease in glycolysis was mediated by loss of constitutive Hif1α signaling, down-regulation of the purine nucleotide cycle enzyme AMPD1, and activation of AMPK. In vivo isotope tracing experiments indicated that myopathic muscle relies on lactate import to supply central carbon metabolites. Inhibition of lactate import reduced steady-state levels of tricarboxylic acid cycle intermediates and compromised the life span of myopathic mice. These data indicate an unexpected mode of metabolic reprogramming in severe mitochondrial myopathy that regulates disease progression.

Targeting adaptive cellular responses to mitochondrial bioenergetic deficiencies in human disease

Mitochondrial dysfunction is increasingly appreciated as a central contributor to human disease. Oxidative metabolism at the mitochondrial respiratory chain produces ATP and is intricately tied to redox homeostasis and biosynthetic pathways. Metabolic stress arising from genetic mutations in mitochondrial genes and environmental factors such as malnutrition or overnutrition is perceived by the cell and leads to adaptive and maladaptive responses that can underlie pathology. Here, we will outline cellular sensors that react to alterations in energy production, organellar redox, and metabolites stemming from mitochondrial disease (MD) mutations. MD is a heterogeneous group of disorders primarily defined by defects in mitochondrial oxidative phosphorylation from nuclear or mitochondrial-encoded gene mutations. Preclinical therapies that improve fitness of MD mouse models have been recently identified. Targeting metabolic/energetic deficiencies, maladaptive signaling processes, and hyper-oxygenation of tissues are all strategies aside from direct genetic approaches that hold therapeutic promise. A further mechanistic understanding of these curative processes as well as the identification of novel targets will significantly impact mitochondrial biology and disease research.

Prevalence and health care costs of mitochondrial disease in Ontario, Canada: A population-based cohort study

Background

Mitochondrial disease prevalence has been estimated at 1 in 4000 in the United States, and 1 in 5000 worldwide. Prevalence in Canada has not been established, though multi-linked health administrative data resources present a unique opportunity to establish robust population-based estimates in a single-payer health system. This study used administrative data for the Ontario, Canada population between April 1988 and March 2019 to measure mitochondrial disease prevalence and describe patient characteristics and health care costs.

Results

3069 unique individuals were hospitalized with mitochondrial disease in Ontario and eligible for the study cohort, representing a period prevalence of 2.51 per 10,000 or 1 in 3989. First hospitalization was most common between ages 0–9 or 50–69. The mitochondrial disease population experiences a high need for health care and incurred high costs (mean = CAD$24,023 in 12 months before first hospitalization) within the single-payer Ontario health care system.

Conclusions

This study provides needed insight into mitochondrial disease in Canada, and demonstrates the high health burden on patients. The methodology used can be adapted across jurisdictions with similar routine collection of health data, such as in other Canadian provinces. Future work should seek to validate this approach via record linkage of existing disease cohorts in Ontario, and identify specific comorbidities with mitochondrial disease that may contribute to high health resource utilization.

Early developmental delay in Leigh syndrome spectrum disorders is associated with poor clinical prognosis

BACKGROUND

Leigh spectrum syndrome (LSS) is a primary mitochondrial disorder characterized by neurodevelopmental regression and metabolic stroke typically in early life. Developmental delay (DD) is known to follow episodes of neurologic regression in LSS, although primary developmental delay (pDD) has been rarely reported. We hypothesized that pDD precedes regression in a broader subset of LSS individuals and may associate with worse long-term educational outcomes.

METHODS

From a retrospective cohort, subjects with pathogenic variant(s) in a nuclear or mitochondrial gene associated with LSS and consistent clinical manifestations and neuroradiological findings. Detailed developmental histories and neurologic outcomes were extracted.

RESULTS

Of 69 LSS subjects, 47 (68.1%) had a history of pDD and 53 (76.8%) had neurodevelopmental regression. We identified 3 distinct developmental phenotypes: [1] pDD followed by regression (N = 31/69, 44.9%), [2] pDD without subsequent regression (16/69, 23.2%), [3] regression without pDD (N = 22/69, 31.9%). A history of pDD was associated with earlier disease onset (p = 0.0003) and worse educational outcomes (OR 22.14).

CONCLUSION

LSS is associated with multiple developmental phenotypes and pDD is associated with negative educational outcomes. pDD occurring prior to neurologic regression suggests that mitochondrial energetics impact developmental trajectories prior to acute metabolic failure and regression, providing an opportunity for earlier diagnosis and/or therapeutic intervention.

Cardiovascular Outcomes in Patients With Mitochondrial Disease in the United States: A Propensity Score Analysis

Mitochondrial disease comprises a wide range of genetic disorders caused by mitochondrial dysfunction. Its rarity, however, has limited the ability to assess its effects on clinical outcomes. To evaluate this relationship, we collected data from the 2016 National Inpatient Sample, which includes data from >7 million hospital stays. We identified 705 patients (mean age, 22 ± 20.7 yr; 54.2% female; 67.4% white) whose records included the ICD-10-CM code E88.4. We also identified a propensity-matched cohort of 705 patients without mitochondrial disease to examine the effect of mitochondrial disease on major adverse cardiovascular events, including all-cause in-hospital death, cardiac arrest, and acute congestive heart failure. Patients with mitochondrial disease were at significantly greater risk of major adverse cardiovascular events (odds ratio [OR]=2.42; 95% CI, 1.29-4.57; P=0.005), systolic heart failure (OR=2.37; 95% CI, 1.08-5.22; P=0.027), and all-cause in-hospital death (OR=14.22; 95% CI, 1.87-108.45; P<0.001). These findings suggest that mitochondrial disease significantly increases the risk of inpatient major adverse cardiovascular events.

Diagnosing newborns with suspected mitochondrial disorders: an economic evaluation comparing early exome sequencing to current typical care

PURPOSE

To determine the value of early exome sequencing (eES) relative to the current typical care (TC) in the diagnosis of newborns with suspected severe mitochondrial disorders (MitD).

METHODS

We used a decision tree-Markov hybrid to model neonatal intensive care unit (NICU)-related outcomes and costs, lifetime costs and quality-adjusted life-years among patients with MitD. Probabilities, costs, and utilities were populated using published literature, expert opinion, and the Pediatric Health Information System database. Incremental cost-effectiveness ratios (ICER) and net monetary benefits (NMB) were calculated from lifetime costs and quality-adjusted life-years for singleton and trio eES, and TC. Robustness was assessed using univariate and probabilistic sensitivity analyses (PSA). Scenario analyses were also conducted.

RESULTS

Findings indicate trio eES is a cost-minimizing and cost-effective alternative to current TC. Diagnostic probabilities and NICU length-of-stay were the most sensitive model parameters. Base case analysis demonstrates trio eES has the highest incremental NMB, and PSA demonstrates trio eES had the highest likelihood of being cost-effective at a willingness-to-pay (WTP) of $200,000 relative to TC, singleton eES, and no ES.

CONCLUSION

Trio and singleton eES are cost-effective and cost-minimizing alternatives to current TC in diagnosing newborns suspected of having a severe MitD.

Susceptibility to COVID-19 in populations with health disparities: Posited involvement of mitochondrial disorder, socioeconomic stress, and pollutants

SARS-CoV-2 is a novel betacoronavirus that has caused the global health crisis known as COVID-19. The implications of mitochondrial dysfunction with COVID-19 are discussed as well as deregulated mitochondria and inter-organelle functions as a posited comorbidity enhancing detrimental outcomes. Many environmental chemicals (ECs) and endocrine-disrupting chemicals can do damage to mitochondria and cause mitochondrial dysfunction. During infection, SARS-CoV-2 via its binding target ACE2 and TMPRSS2 can disrupt mitochondrial function. Viral genomic RNA and structural proteins may also affect the normal function of the mitochondria-endoplasmic reticulum-Golgi apparatus. Drugs considered for treatment of COVID-19 should consider effects on organelles including mitochondria functions. Mitochondrial self-balance and clearance via mitophagy are important in SARS-CoV-2 infection, which indicate monitoring and protection of mitochondria against SARS-CoV-2 are important. Mitochondrial metabolomic analysis may provide new indicators of COVID-19 prognosis. A better understanding of the role of mitochondria during SARS-CoV-2 infection may help to improve intervention therapies and better protect mitochondrial disease patients from pathogens as well as people living with poor nutrition and elevated levels of socioeconomic stress and ECs.

α-ketobutyrate links alterations in cystine metabolism to glucose oxidation in mtDNA mutant cells

Pathogenic mutations in the mitochondrial genome (mtDNA) impair organellar ATP production, requiring mutant cells to activate metabolic adaptations for survival. Understanding how metabolism adapts to clinically relevant mtDNA mutations may provide insight into cellular strategies for metabolic flexibility. In this study, we use ¹³C isotope tracing and metabolic flux analysis to investigate central carbon and amino acid metabolic reprogramming in isogenic cells containing mtDNA mutations. We identify alterations in glutamine and cystine transport which indirectly regulate mitochondrial metabolism and electron transport chain function. Metabolism of cystine can promote glucose oxidation through the transsulfuration pathway and the production of α-ketobutyrate. Intriguingly, activating or inhibiting α-ketobutyrate production is sufficient to modulate both glucose oxidation and mitochondrial respiration in mtDNA mutant cells. Thus, cystine-stimulated transsulfuration serves as an adaptive mechanism linking glucose oxidation and amino acid metabolism in the setting of mtDNA mutations.

A retrospective analysis of health care utilization for patients with mitochondrial disease in the United States: 2008-2015

BACKGROUND

Mitochondrial disease (MD) is a heterogeneous group of disorders characterized by impaired energy production caused by abnormal oxidative phosphorylation. Diagnosis of MD is challenging given the variability in how the disease can affect an individual's neurologic, cardiovascular, ophthalmologic, or gastroenterological systems. This study describes the health care utilization and cost in patients diagnosed with MD.

METHODS

This study was a retrospective claims analysis based on data from the Truven Health Analytics MarketScan Database and Milliman's Consolidated Health Cost Guidelines Sources Database. For the purpose of this study the diagnosis of MD was defined by ICD-9-CM (prior to October 2015), and ICD-10-CM (October 2015 or later), and included patients identified between January 1, 2008 to December 31, 2015. ICD-9-CM code of 277.87 (disorders of mitochondrial metabolism) and the ICD-10-CM codes of E88.40, E88.41, E88.42 and E88.49 (mitochondrial metabolism disorders) were used as inclusive criteria. Patients were included if they had at least six months of exposure after the first MD-related claim occurrence, and either one MD claim in the inpatient setting OR two MD claims in an outpatient setting. Claims of MD patients are compared to those of a general insured total member population, as well as to those from multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS) patients.

RESULTS

During the study period, 3825 patients between the ages of 0 and 15 (pediatric) and 4358 patients 16 years of age and greater (adult) were identified. Total allowed per member per month (PMPM) cost for pediatric patients was $4829 and $3100 for adults, compared with an average of $202 and $486, respectively, for the total member population. The greatest drivers of costs based on allowed claims came from inpatient, surgery, and prescription medications. In the adult population, MD imposes a PMPM cost burden that was comparable to that observed for multiple sclerosis ($3518) and ALS ($3460) patients.

CONCLUSIONS

This retrospective claim study highlights the significant differences in the cost of medical care for MD patients compared to those of a general population. Mitochondrial disorders are associated with multisystem disease manifestations and a greater care and cost burden similar to other devastating neuromuscular diseases.

Mitochondrial Disease in Children: The Nephrologist's Perspective

Mitochondrial diseases (MD) are a heterogeneous group of clinical syndromes characterized by the involvement of different organ systems. They constitute the most prevalent hereditary metabolic disease group.

OBJECTIVE

To review the importance of the kidney in MD from the nephrologist's perspective within the setting of a pediatric tertiary reference center.

STUDY DESIGN

Retrospective study of children (<18 years) with MD followed between 2000 and 2016 at a tertiary Spanish center.

RESULTS

52 patients were included. The mean age at the time of the study was 10 years (SD ± 5.1). The mean follow-up time was 6.1 years (SD ± 4.7). The median age at diagnosis was 2.5 years (0.3-13.5).The median number of affected systems was two (range 1-6). The nervous system was the most affected system, with 51 patients (~98%) presenting with neurological involvement. 20 patients (~40%) presented with endocrinological manifestations, 18 (~35%) with vision problems, 16 (~30%) with gastrointestinal symptoms, 5 (~10%) patients developed hearing impairment, and 6 (~10%) cardiac disease.We detected renal involvement in 13 patients (25%). Eight patients had tubular disease, most frequently hypercalciuria with hypouricemia and five patients had glomerular involvement, with proteinuria and/or decreased glomerular filtration rate as the most frequent symptoms. Only 21 patients (~40%) had been seen by a pediatric nephrologist.

CONCLUSIONS

Renal disease was a common occurrence in patients with mitochondrial disease, present in our study in 25% of patients. A regular screening of renal function parameters and the involvement of a nephrologist as part of the multidisciplinary approach to mitochondrial disease appears warranted.