Neuropsychiatric Function Improvement in Pediatric Patients with Phenylketonuria

OBJECTIVE

To evaluate effects of sapropterin dihydrochloride on blood phenylalanine (Phe) and symptoms of neuropsychiatric impairment in children and adolescents with phenylketonuria (PKU).

STUDY DESIGN

PKU subjects 8-17 years of age (n = 86) were randomized to double-blind treatment with sapropterin (n = 43) or placebo (n = 43) for 13 weeks, then all received open-label sapropterin therapy for an additional 13 weeks. Blood Phe and symptoms of inattention, hyperactivity/impulsivity (Attention-Deficit/Hyperactivity Disorder Rating Scale IV [ADHD RS-IV]), executive functioning (Behavior Rating Inventory of Executive Function), depression (Hamilton Rating Scale for Depression), and anxiety (Hamilton Rating Scale for Anxiety) were assessed.

RESULTS

Following the 13-week randomization phase, the sapropterin and placebo groups had mean changes in blood Phe of -20.9% and +2.9%, respectively. Corresponding least square mean differences in ADHD RS-IV scores were significantly greater for the sapropterin vs the placebo group: Total (-3.2 points, P = .02), Inattention subscale (-1.8 points, P = .04), and Hyperactivity/Impulsivity subscale (-1.6 points, P = .02). Forest plots favored sapropterin treatment over placebo for all ADHD RS-IV and Behavior Rating Inventory of Executive Function indices. There were no significant differences in reported problems with attention or executive function between the 2 groups at baseline or at week 26 following the 13-week open-label treatment period. Anxiety and depression scores did not differ significantly between cohorts at any time. Sapropterin was well tolerated, with a favorable safety profile.

CONCLUSIONS

Sapropterin reduced blood Phe and was associated with significant improvement in parent-reported symptoms of inattention, hyperactivity/impulsivity, and executive functioning in children and adolescents with PKU.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01114737. Registered 27 April 2010, https://clinicaltrials.gov/ct2/show/NCT01114737.

Neuropsychiatric comorbidities in adults with phenylketonuria: A retrospective cohort study

Adults with phenylketonuria (PKU) may experience neurologic and psychiatric disorders, including intellectual disability, anxiety, depression, and neurocognitive dysfunction. Identifying the prevalence and prevalence ratios of these conditions will inform clinical treatment. This nested, case-controlled study used International Classification of Diseases, Ninth Revision (ICD-9) codes from the MarketScan® insurance claims databases from 2006 to 2012 and healthcare claims data for US-based employer and government-sponsored health plans. Prevalence and prevalence ratio calculations of neuropsychiatric comorbidities for adults (≥20years old) with PKU were compared with two groups [diabetes mellitus (DM) and general population (GP)] matched by age, gender, geographic location, and insurance type. Age cohorts (i.e., 20-29, 30-39, 40-49, 50-59, 60-69, and 70+years, and a combined subset of 20-39) were used to stratify data. The PKU cohort experienced significantly higher rates of several comorbid neurologic, psychiatric and developmental conditions. Compared to GP, PKU was associated with significantly higher prevalence for numerous neuropsychiatric conditions, most notably for intellectual disability (PR=7.9, 95% CI: 6.4-9.9), autism spectrum disorder (PR=6.1, 95% CI: 3.6-10.4), Tourette/tic disorders (PR=5.4, 95% CI: 2.1-14.1), and eating disorders (4.0, 95% CI: 3.2-5.0). Rates of fatigue/malaise, epilepsy/convulsions, sleep disturbance, personality disorders, phobias, psychosis, and migraines among those with PKU exceeded rates for the GP but were comparable to those with DM, with significantly lower rates of concomitant disorders occurring in younger, compared to older, adults with PKU. Lifelong monitoring and treatment of co-occurring neuropsychiatric conditions are important for effective PKU management.

Adherence to clinic recommendations among patients with phenylketonuria in the United States

OBJECTIVE

Assess current management practices of phenylketonuria (PKU) clinics across the United States (US) based on the key treatment metrics of blood phenylalanine (Phe) concentrations and blood Phe testing frequency, as well as patient adherence to their clinic's management practice recommendations.

METHODS

An online survey was conducted with medical professionals from PKU clinics across the US from July to September 2015. Forty-four clinics participated in the survey and account for approximately half of PKU patients currently followed in clinics in the US (Berry et al., 2013).

RESULTS

The majority of PKU clinics recommended target blood Phe concentrations to be between 120 and 360μM for all patients; the upper threshold was relaxed by some clinics for adult patients (from 360 to 600μM) and tightened for patients who are pregnant/planning to become pregnant (to 240μM). Patient adherence to these recommendations (percentage of patients with blood Phe below the upper recommended threshold) was age-dependent, decreasing from 88% in the 0-4years age group to 33% in adults 30+ years. Patient adherence to recommendations for blood testing frequency followed a similar trend. Higher staffing intensity (specialists per 100 PKU patients) was associated with better patient adherence to clinics' blood Phe concentrations recommendations.

CONCLUSION

Clinic recommendations of target blood Phe concentrations in the US are now stricter compared to prior years, and largely reflect recent guidelines by the American College of Medical Genetics and Genomics (Vockley et al., 2014). Adherence to recommended Phe concentrations remains suboptimal, especially in older patients. However, despite remaining above the guidelines, actual blood Phe concentrations in adolescents and adults are lower than those reported in the past (Walter et al., 2002; Freehauf et al., 2013). Continued education and support for PKU patients by healthcare professionals, including adequate clinic staffing, are needed to improve adherence. Future research is needed to understand how to improve adherence to reduce the number of patients lost to follow-up, as the findings of this and similar surveys do not address how to keep patients in clinic.

In Vitro Stability of Sapropterin Dihydrochloride From Crushed Tablets Mixed in Applesauce, Pudding, and Infant Formula

Sapropterin is approved to reduce blood phenylalanine levels in patients with hyperphenylalaninemia due to tetrahydrobiopterin-responsive phenylketonuria. The current Food and Drug Administration—approved labeling states that sapropterin tablets should be dissolved in 4 to 8 oz of water or apple juice; however, numerous requests for information regarding the feasibility of administering crushed sapropterin tablets in infant formula or soft foods such as applesauce and pudding suggest that the current recommendations for administration may not be suitable for many infants and small children. To determine the safety of administering the medication in formula or soft foods, powdered tablets representing 200 mg of sapropterin were thoroughly mixed with applesauce, lemon pudding, and 3 brands of phenylalanine-free infant formula, incubated for up to 60 minutes at room temperature and then analyzed for sapropterin content. The results indicate there was no significant change in the amount of sapropterin present in any mixture after 60 minutes.

Compliance with childhood cholesterol screening among members of a prepaid health plan

OBJECTIVE

To assess compliance with cholesterol screening and intervention by children who were members of a prepaid health plan in which there was no financial barrier to intervention.

RESEARCH DESIGN

Children with family histories of hypercholesterolemia, coronary heart disease, and stroke were advised to have a random cholesterol test. Those with total cholesterol levels of 4.80 mmol/L (185 mg/dL) or higher were asked to return for a fasting blood test; of this group, compliant subjects with low-density lipoprotein values of 3.25 mmol/L (125 mg/dL) or higher were offered a nutrition program.

SETTING

Kaiser Permanente Medical Center, Oakland, Calif.

SUBJECTS AND PARTICIPANTS

The parents of 1160 children aged 2 to 18 years who had routine pediatric appointments at Kaiser Permanente Medical Center were asked to complete screening forms on family history.

SELECTION PROCEDURES

Children with family histories of hypercholesterolemia, coronary heart disease, and stroke were advised to have a random cholesterol test. Subjects with total cholesterol levels of 4.80 mmol/L or higher were asked to return for a fasting test, and subjects with low-density lipoprotein levels of 3.25 mmol/L or higher were offered a nutrition program.

INTERVENTIONS

Telephone call, letter, low-cholesterol diet, and nutrition program.

MAIN OUTCOME MEASURES

Of the 1,160 subjects contacted, 529 (46%) had positive family histories. Of these subjects, random blood cholesterol levels were determined for 369 (70%); 160 (30%) did not comply. Ninety-three subjects had total cholesterol levels of 4.80 mmol/L or higher; of these, 35 (38%) did not comply with follow-up testing. Of the 58 compliant subjects, 25 (43%) had low-density lipoprotein values of 3.25 mmol/L or higher and were offered either a 3-week or a 6-week nutrition program. Only nine subjects (36%) enrolled; 16 (64%) did not comply.

CONCLUSIONS

Parents do not comply well with a childhood cholesterol screening program that involves two blood tests and moderately intensive educational intervention. Compliance is an important component of cholesterol screening and intervention.