PARENTAL PSYCHOLOGICAL ISSUES, QUALITY OF LIFE AND CORRELATIONS WITH PATIENTS' DIETARY COMPLIANCE IN PHENYLKETONURIA

Background. Phenylketonuria (PKU) is an inherited metabolic disease that can be diagnosed and successfully treated early from birth with a phenylalanine-restricted dietary regimen. Nevertheless, PKU parents are found to be at risk for psychological and quality of life (QoL) maladjustments. In chronic illness, parental disturbances are found to influence adherence to treatments of their children. Objectives. The study aimed to: 1) evaluate the psychological issues and the quality of life of parents of PKU patients distinguishing the disease load from the treatment load; 2) assess if parental psychological functioning is related to blood phenylalanine (Phe) levels of their children, as indicators of metabolic control in relation to dietary compliance. Methods. The study is a cross-sectional study involving 146 parents of both patients with PKU (who need a phe-restricted dietary regimen) and patients with a mild form (mild hyperphenylalaninemia - MHP) who do not require a dietary treatment. Socio-demographic data of both parents and patients together with patients’ clinical data (patient’s phenotype and patient’s Phe level) were retrieved. Self-report measures of psychological distress and symptoms (SCL-90-R), anxiety (STAI-Y), depression (BDI-2), anger (STAXI-2) and quality of life (SF-36) were collected. For aim 1, the means scores of all scales were compared to the appropriate normative samples; then, differences in SCL90-R, STAI, BDI-II, STAXI-II subscales and SF-36 dimensions mean scores between parents of PKU vs parents of MHP patients were tested through MANCOVA analyses, with socio-demographic variable as covariates in order to control for potential confounders. For aim 2, to assess if the parental psychological issues and quality of life can predict the dietary compliance, logistic regressions with a block entry method were performed. Results. Globally, parents showed psychological characteristics and quality of life comparable to the normative sample; nevertheless, out of the normative cut off were the following (in brackets, percentage of parents): psychological distress (11,5%), state (25,3%) and trait (29,1%) anxiety, depressive symptoms (16,0%), hyper-control of anger expression (16,1%) and, as concern quality of life, Bodily pain (32,6%), General health (17,4%), Vitality (14,2%), Social functioning (27,7%), Emotional functioning (14,9%), and Mental health (20,6%). Mothers (vs fathers) and parents with a low (vs high) educational level showed statistically significant poor emotional outcomes. Parents of PKU (vs MHP) patients reported statistically higher values of depressive symptoms on the somatic-affective side and lower values of Physical activity and General health QoL scales. Patients optimal Phe levels were found to be predicted (R2=0,34, p=0.031) by the following parental psychological characteristics: high levels of depressive complaints on the somatic-affective side (B=1.52, p=0.011) and low levels on the cognitive side (B=0.59, p=0.050), high level of anger control (B=0.77, p=0.043) and low level of anger expression outward (B=1.35, p=0.032). Optimal Phe levels were predicted also by the following parental quality of life dimensions (R2=0,25, p=0.05): a lower Vitality (B=0.93, p=0.035), a lower Social functioning (B=0.94, p=0.027) and a higher Mental health (B=1.07, p=0.043). Conclusions. Parenting patients with phenylketonuria do not generally affect psychological well-being and quality of life. Specific socio-demographic conditions are more at risk of disturbances; maladjustments are also related to the dietary management load and to the effort of maintaining an optimal adherence to diet of their children. Help children to remain adherent to the diet seems to affect the parents’ social functioning. Results are useful to help clinicians to identify specific situations at risk for non adherence and may have implications for setting up interventions to improve compliance to diet, together with parental and family well-being.