Change in children's functional gastrointestinal disorders diagnostic status measured by Rome IV Diagnostic Questionnaire on Pediatric Functional Gastrointestinal Disorders (R4PDQ) - Child: Non-numerical self-report form for Children and Adolescents (10 years and older) measured from baseline to three months and from baseline to six months for analysis of effect as a self-rating scale from baseline to three months and from baseline to six months for analysis of effect.

Change in pain intensity measured with a self-rating scale daily during two weeks at baseline, daily during two weeks after 3 months and daily during two weeks after 6 months for analysis of effect. The Faces Pain Scale is a self-report measure used to assess the intensity of children's pain. Faces have four faces representing least pain and most pain on equal intervals on a scale from 0 (no pain)-10 (worst pain). Its validity is supported by a strong positive correlation (r=0.93, N=76) with a visual analogue scale (VAS) measure in children aged 5-12 years. The metric for scoring (0-10) conforms closely to a linear interval scale.Higher scores indicates higher levels of pain.

Change in quality of life from baseline to three months and from baseline to six months measured with a self-report scale that measures quality of life in adolescents. PedsQL Generic Core scales is a 23-item scale ranging from 0 (never) to 4 (almost always). Improvements yield increased values. The PedsQL is shown to distinguish between healthy children and adolescents and pediatric patients with acute or chronic health conditions and demonstrate acceptable reliability and validity.

Change in Gastrointestinal symptom-specific behaviors measured with a self-rating scale from baseline to three months and from baseline to 6 months, for analysis of effect. The BRQ-C comprise 11 items on a 7 point-scale, with only endpoints defined: never (0) and always (7). Higher scores indicates higher levels of gastrointestinal symptoms.

A questionnaire that assesses the perceived severity of 24 nonspecific somatic symptoms. Items are based off of the symptom criteria for somatization disorders as defined by the Diagnostic and Statistical Manual of Mental Disorders (DSM). We will use the subscale for gastrointestinal symptoms (CSI gastro) with questions concerning presence of gastrointestinal symptoms measured with a 7-item scale ranging from 0 (not at all) to 4 (very much) measured from baseline to three months and from baseline to six months. Higher scores indicates higher levels of somatization.

The SCAS-S assesses anxiety in children. The frequency of anxiety symptoms is rated on a 4-point scale, with answers ranging from never (0) to always (3). Higher scores indicates higher levels of anxiety. The SCAS-S will be assessed from baseline to three months and from baseline to six months.

Child Depression Inventory (CDI) is a self-measure of child depression symptoms. The short version of the CDI (CDI-S) consists of 10 items graded from 0 (no symptoms) to 2 (severe symptoms). The questionnaire covers depressive symptoms such as self-blame, loss of appetite and insomnia. The CDI-S has shown high correlation to other measures of depression and should be considered a valid measure of depression symptoms. Symptoms measured from baseline to three months and from baseline to six months. Higher scores indicates higher levels of depression.