Access to Low Protein-Modified Food Associated with Clinical Biomarkers in Patients with Phenylketonuria Open Access

Abstract

Background: Low protein-modified foods (LPMF) are thought to provide satiety and variety to patients diagnosed with Phenylketonuria (PKU) who have more severe phenylalanine (Phe) restrictions. We aim to understand whether there is an association between access to LPMF and metabolic control in patients with PKU. Additionally, we hope to evaluate whether there are differences in control by frequency of one’s interaction with the Metabolic Nutrition Therapy 4 Prevention (MNT4P) LPMF bridge program.

Methods: We used invoice data from MNT4P’s novel LPMF bridge program to identify a cohort of patients with PKU and quantify the number of times each patient accessed LPMF in their first year participating in the program. A retrospective chart review of biomarker data and anthropometrics was then completed for eligible patients. The association between LPMF orders and log-transformed median blood Phe levels was quantified through multivariable fixed-effects linear regression, as was that between frequency of interaction with the program and blood Phe levels.

Results: A total of 37 patients were included in the analysis. The median age of the study population was 3.8 years (IQR 0.8 – 15.1), 9 (24%) were receiving concurrent treatment with sapropterin dihydrochloride, and the median number of LPMF orders during the follow-up period was four (range 1 – 12). When adjusting for filter paper submission adherence and age, participation in the LPMF program was associated with median blood Phe levels 0.70 times those recorded in the baseline year (95% CI 0.38 – 1.31; adjusted R² 0.67, p < 0.001). Frequency of LPMF ordering also was associated with differences in median blood Phe levels (adjusted R² 0.66, p <0.001). Among patients ordering 1-4 times, there was a 29% reduction compared baseline (95% CI 0.38 – 1.33); those ordering 5-12 times saw a 34% reduction (95% CI 0.33 – 1.32). 

Conclusion: Access to LPMF was associated with reduced median blood Phe levels in patients with PKU. This indicates that improving access to LPMF may have clinical utility and public health salience in the management of PKU.

Table of Contents

Introduction. 1

Methods. 3

Study population. 3

Data Collection. 4

Data Analysis. 5

Results. 6

Table 1. 9

Figure 1. 9

Table 2. 10

Discussion. 10

Limitations. 12

Conclusion. 13

Acknowledgements. 13

References 14

About this Master's Thesis

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School	Rollins School of Public Health
Department	Epidemiology
Subfield / Discipline	Epidemiology - MPH & MSPH
Degree	M.P.H.
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Public Health Health Sciences, Epidemiology
Keyword	low protein-modified food dietary management Phenylketonuria healthcare access
Committee Chair / Thesis Advisor	Terryl J. Hartman, Emory University Rani Singh, Emory University

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