Young Lifelines participants (13-17 years old) participating in general assessment 2A filled in a digital questionnaire about themselves.
The 2A Child Questionnaire was followed by 2A Visit 1, on average within xx days (+/- yy days).
The 2A Child Questionnaire is procedurally equivalent to the

N=xxx parents filled in a paper variant of the 2A Child Questionnaire, N=yyy parents filled in a digital variant of the 2A Child Questionnaire.

The 2A Child Questionnaire contained the following sections and subsections:

• Education
• Family composition
• Personal data

• Acne
• Allergies
• Allergies & Asthma (ISAAC)
• Cold/Flu
• Digestive symptoms
• Ear conditions
• Eye Conditions
• Fatigue (general)
• Fatigue (PROMIS)
• Insomnia
• Kidney & bladder diseases
• Mental illnesses
• Musculoskeletal symptoms
• Neurological disorders
• Respiratory problems (general)
• Skin conditions
• Symptoms (general)

• Electronic device use
• Exposure to smoking
• Hobbies & activities
• Mobile phone use (MOB)
• Pets & livestock
• Physical activity (sports)
• Sleep (general)

• Medication
• Treatment (general)

• Child behavior (CBCL)
• Familial bonds
• Learning difficulties
• Social functioning (general)
• Social functioning (PROMIS)
• Stress (general)

• Anthropometry (self-reported)
• Subjective health (general)

• Physical development
• Diet (general)