Clinical characteristics and management of Spanish adult patients with phenylketonuria

Objectives

To describe the sociodemographic and clinical characteristics and management of patients with phenylketonuria (PKU) followed in centres, services, and reference units (CSUR) or clinical excellence units specialised in inborn errors of metabolism (IEM). Additionally, to determine patients’ health-related quality of life (HRQoL).

Methods

Observational, cross-sectional, descriptive study conducted with Spanish PKU patients attending CSUR centres or clinical excellence units specialised in IEM during the study period.

Results

The study included 55 patients (54 adults and one teenager) with different PKU phenotypes. The mean (SD) age was 32.1 (9.7) years, with 69.1% women.

The most frequent phenotype at diagnosis was classical PKU (67.3%). Mean (SD) plasma Phe levels at diagnosis were 901.9 (606.1) µmol/L and 422.8 (288.9) µmol/L in the last year.

Neurological symptoms were present in 23.6% of patients, the most frequent being intellectual disability (21.8%). Psychological symptoms were present in 34.5% of patients, the most frequent being anxiety (14.5%) and depression (12.7%).

Of the patients, 85.5% responded to the EQ-5D-5L questionnaire. Of these, 44.7% of patients reported no anxiety or depression, while 34.0% had mild anxiety or depression. The mean (SD) EQ-VAS value was 80.9 (15.2).

Forty-one (74.5%) patients responded to the PKU-QoL questionnaire. The results indicated that PKU patients perceived the impact of their disease to be moderate across all domains included in the questionnaire.

Conclusions

Adults with PKU may experience neurological or psychological symptoms including intellectual disability, anxiety, and depression. However, their HRQoL was found to be good and comparable to that of the general population.