Table 2 The five dimensions of adherence and topics related to PKU treatment according to literature

Social/Economic-related factors

Poor social or family support; family skills and dynamics [15, 40, 44]

Health care team and system-related factors

Poor access to the health system [15]

Failure in receiving medication from public sources [12]

Feeling of detachment in relation to the medical staff [42]

Condition-related factors

Lack of perceived disease symptoms [15, 40]

Dealing with diagnosis as a potential risk and not as an established disease [37, 38]

Therapy-related factors

Time constraints to prepare meals [15, 35, 41]

Difficult in preparing adequate, varied and nutritious meals [15, 34]

Difficulties about what to order from the menu when eating out [15, 39]

Low palatability of medical food [14, 36, 39, 40]

High level of dietary restrictions [12]

Patient-related factors

Lack of ability to cope with food temptation [36, 40, 41]

Fear of being treated differently by others, fear of stigma [15, 36, 38, 40]

Feeling ashamed to talk about diagnosis with others [41]

Restriction on social life [35, 36]

Poor knowledge about the disease [15, 39]

Poor knowledge about the treatment [15]

Lack of motivation to follow the treatment [15]

Denial of condition [15]

Lack of conviction that poor compliance will have adverse effects [15]