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



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).



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.



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.
Medical Affairs, BioMarin Pharmaceutical, Inc., Novato, CA, United States. Electronic address: ejurecki@bmrn.com.
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Jurecki
Department of Psychiatry, University of California, Los Angeles, CA, United States; Department of Pediatrics, and Human Genetics, University of California, Los Angeles, CA, United States.
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Cederbaum
Department of Clinical Nutrition, Children's Hospital of Wisconsin, Milwaukee, WI, United States; Department of Genetics, Children's Hospital of Wisconsin, Milwaukee, WI, United States.
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Kopesky
Trinity Partners, Waltham, MA, United States.
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Perry
Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, United States.
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Rohr
Division of Genetics and Metabolism, University of South Florida, Florida, United States.
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Sanchez-Valle
Department of Pediatrics, Division of Medical Genetics, University of Utah, Salt Lake City, UT, United States.
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Viau
Trinity Partners, Waltham, MA, United States.
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Sheinin
Medical Affairs, BioMarin Pharmaceutical, Inc., Novato, CA, United States.
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Cohen-Pfeffer
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000554:Ambulatory Care Facilities; D002648:Child; D002675:Child, Preschool; D004311:Double-Blind Method; D005260:Female; D006282:Health Personnel / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance / Q000706:statistics & numerical data*; D010649:Phenylalanine / Q000097:blood*; D010661:Phenylketonurias / Q000378:metabolism*; D017410:Practice Guidelines as Topic; D011795:Surveys and Questionnaires; D014481:United States; D055815:Young Adult
D010649:Phenylalanine
ACMG guidelines; Adherence; Adults; Blood phenylalanine; Phenylketonuria