Original article Retrospective, observational data collection of the treatment of phenylketonuria in the UK, and associated clinical and health outcomes

Objective: To determine the percentage of phenylketonuria (PKU) subjects using current treatment strategies whose phenylalanine (Phe) concentrations diverge from the UK target guidelines for PKU. Research design and methods: This retrospective, observational, chart review was conducted between 2004 and 2008 at three specialist PKU treatment centres in the UK, and included 125 eligible subjects: 20 adults (18þ years, with � 4 Phe concentrations measured per year) and 105 children (up to age 17, with � 6 Phe concentrations measured per year). Results: The mean percentage of subjects with at least 70% of Phe concentrations within the target range for 0–5year olds, 6–10 year olds and 11–17 year olds was similar across the period 2004–2008 (57.0%, 56.5% and 57.1%, respectively) and lower (39.4%) in the 18þ year age group. For all ages, across the period the mean was 54.4%. Further analysis of the adult population showed that some subjects were very good at complying with treatment and reporting Phe concentrations. Overall, the percentage of 100% compliance was 15.7% in females and 13.7% in males. The mean duration that subjects were ‘out of range’ of target Phe concentrations over the study period was approximately 1 year and 3 months and the mean duration for ‘significantly out of range’ values was approximately 9 months. The most common type of contact made with subjects was by telephone, with a mean number of 16 calls per subject per year.