Infant mortality in Brazil attributable to inborn errors of metabolism associated with sudden death: a time-series study (2002-2014).

BACKGROUND: The literature suggests that 0.9 to 6% of infants who die unexpectedly may have had a metabolic disorder. At least 43 different inborn errors of metabolism (IEMs) have been associated with sudden death (SUDI). To date, the frequency of IEM-associated SUDI has not been studied in Brazil. The present study sought to characterize infant mortality related to IEMs known to cause SUDI disaggregated by each of the regions of Brazil. METHODS: This was a descriptive, cross-sectional, population-based study of data obtained from the Brazilian Ministry of Health Mortality Information System (SIM). Death records were obtained for all infants (age < 1 year) who died in Brazil in 2002-2014 in whom the underlying cause of death was listed as ICD-10 codes E70 (Disorders of aromatic amino-acid metabolism), E71 (Disorders of branched-chain amino-acid metabolism and fatty-acid metabolism), E72 (Other disorders of amino-acid metabolism), or E74 (Other disorders of carbohydrate metabolism), which are known to be associated with SUDI. RESULTS: From 2002 to 2014, 199 deaths of infants aged < 1 year were recorded in the SIM with an underlying cause corresponding to one of the IEMs of interest. The prevalence of IEM-related deaths was 0.67 per 10,000 live births (0.58-0.77). Of these 199 deaths, 18 (9.0%) occurred in the North of Brazil, 43 (21.6%) in the Northeast, 80 (40.2%) in the Southeast, 46 (23.1%) in the South, and 12 (6.0%) in the Center-West region. Across all regions of the country, ICD10-E74 was predominant. CONCLUSIONS: This 13-year time-series study provides the first analysis of the number of infant deaths in Brazil attributable to IEMs known to be associated with sudden death.

Acute liver failure in under two year-olds--are there markers of metabolic disease on admission?

INTRODUCTION: The early establishment of an etiology for acute liver failure (ALF) in infants is essential for the start of adequate treatment in the shortest timeframe possible. AIM: To identify markers of inherited metabolic disease on admission in children under two years of age with ALF. MATERIAL AND METHODS: A retrospective review of the medical records of all children (< 2 years old) with ALF admitted to the pediatric hepatology or intensive care units of a tertiary center over a twenty-three year period (January 1989 to December 2011) was done. Patients were divided into two groups: with (group A) or without (group B) a metabolic etiology. Clinical and laboratory parameters on admission were compared. RESULTS: Twenty-three children met inclusion criteria. Twelve had ALF of metabolic origin (group A). The median age in this group was 2.25 (Q1-Q3: 0.63-4.65) months and in group B 8.0 (Q1-Q3: 1.5-15) months. History of failure to thrive and/or vomiting was more frequent in group A (p = 0.022). Age, gender, encephalopathy and left ventricular hypertrophy were similar in both groups (p = 0.147, p = 1.000, p = 0.637, p = 1.000, respectively). Laboratory tests on admission (plasma lactate, ammonia, cholesterol, phosphate, INR, glucose, bilirubin, ALT, base excess and the presence of reducing substances in urine) showed no statistically significant differences between groups. CONCLUSION: This study showed that although infants with inborn errors of metabolism showed a trend towards lower age at presentation, the only marker of inherited metabolic disease found on admission was history of vomiting and/or failure to thrive.

Renal replacement therapy in the treatment of confirmed or suspected inborn errors of metabolism.

OBJECTIVE: Analysis of mortality and risk factors for mortality in the use of renal replacement therapy to correct metabolic disturbances associated with confirmed or suspected inborn errors of metabolism. STUDY DESIGN: A retrospective review of an institutional review board-approved pediatric acute renal failure data base at the University of Michigan. Eighteen patients underwent 21 renal replacement therapy treatments for metabolic disturbances caused by urea cycle defects (n = 14), organic acidemias (n = 5), idiopathic hyperammonemia (n = 1), and Reye syndrome (n = 1). RESULTS: There were 14 boys (74%) and 4 girls (26%), with a mean age and weight of 56.2 +/- 71.0 months and 18.5 +/- 19.2 kg, respectively, at the initiation of renal replacement therapy. Overall treatment mortality rate was 57.2% (12 of 21 treatments), with 11 of the 18 patients (61.1%) dying before hospital discharge. Two-year follow-up on those patients demonstrated that 5 patients (71.4%) remained alive. Initial therapy with hemodialysis was associated with improved survival. Ten treatments (47.6%) required transition to another form of renal replacement therapy to maintain ongoing metabolic control, with a mean duration of 6.1 +/- 9.8 days. Time to renal replacement therapy >24 hours was associated with an increased risk of mortality, whereas a blood pressure >5th percentile for age at the initiation of therapy and the use of anticoagulation were associated with a decreased risk of mortality. CONCLUSIONS: Renal replacement therapy can correct the metabolic disturbances that accompany suspected or confirmed inborn errors of metabolism. Our experience demonstrates an approximately 60% mortality rate associated with renal replacement treatment, with more than 70% of survivors living longer than 2 years.

Newborn screening with tandem mass spectrometry: examining its cost-effectiveness in the Wisconsin Newborn Screening Panel.

OBJECTIVE: To examine the cost-effectiveness of tandem mass spectrometry (MS/MS) in a neonatal screening panel for 14 fatty acid oxidation and organic acidemia disorders in the Wisconsin Newborn Screening Program. STUDY DESIGN: An incremental cost-effectiveness analysis with a hypothetical cohort of 100,000 infants was performed. A threshold of $50,000/QALY (quality-adjusted life-year) was used to determine whether screening for medium-chain acyl-CoA dehydrogenase deficiency (MCAD) alone is cost-effective or whether additional disorders would need to be incorporated into the analysis to arrive at a conclusion regarding the overall cost-effectiveness of MS/MS. RESULTS: Under conservative assumptions, screening for MCAD alone yields an incremental cost-effectiveness ratio of $41,862/QALY. With the use of more realistic assumptions, screening becomes more cost-effective ($6008/QALY) and remains cost-effective so long as the incremental cost of screening remains under $13.05 per test. Adding the incremental costs of detecting the 13 other disorders on the screening panel still yields a result well within accepted norms for cost-effectiveness ($15,252/QALY). CONCLUSIONS: In Wisconsin, MS/MS screening for MCAD alone appears to be cost-effective. Future analyses should examine the cost-effectiveness of alternative follow-up and treatment regimens for MCAD and other panel disorders.

Recurrent apparent life-threatening events during infancy: a manifestation of inborn errors of metabolism.

To determine how often inborn errors of metabolism may cause unexplained apnea or recurrent apparent life-threatening events in infants, we retrospectively reviewed the records of 166 infants who were referred for apnea evaluation. A metabolic disorder was identified in 7 infants (4.2%), all of whom had recurrent apparent life-threatening events.