Psychosocial Situation of Children With Rare Solid Abdominal Tumors and Their Families

Quality of Life (QoL) of the parents, assessed from the perspective of the parents by the instrument "European Quality of Life Five Dimension" (EQ-5D; Hinz et al., 2006). The instrument consists of 5 dimensions, which are answered on a three-point scale. Higher scores indicate greater QoL.

Health-related Quality of Life (HRQoL) of the parents, assessed from the perspective of the parents by the "Short-Form-12" (SF-12; Morfeld, Kirchberger & Bullinger, 2011). The instrument consists of 12 items. Higher scores indicate greater HRQoL.

Severity of depression, will be assessed with the 9-question Patient Health Questionnaire (PHQ-9; Löwe et al., 2015). The instrument consists of 9 items. Higher scores indicate greater depression levels.

Generalizied Anxiety Disorder Scale-7 (GAD-7; Spitzer, Kroenke & Löwe, 2006). The instrument consists of 7 items. Higher score indicate greater anxiety levels.

Mental health of the parents, assessed from the perspective of the parents by the "Brief Symptom Inventory-18" (BSI-18; Spitzer et al., 2011). The instrument consists of 18 items, which are answered on a five-point Likert scale (0 to 4). Higher BSI scores indicate greater psychological distress.

Health-related quality of life of the chronically-ill children/adolescents, assessed from the perspective of the child/adolescent (from 10 years of age) and from the perspective of the parents by the "Pediatric Quality of Life Inventory 4.0" (Peds-QL 4.0; (Varni, Seid, & Kurtin, 2001). Items will be linearly transformed to a scale of 0 to 100, with higher scores indicating better HRQoL.

Psychiatric disorders of the chronically-ill children/adolescents assessed perspective of the child/adolescent and from the perspective of the parents by the "Strengths and Difficulties Questionnaire" (SDQ; Klasen, Woerner, Rothenberger, & Goodman, 2003). Items are rated on a three-point Likert scale (0 to 2). Higher scores represent greater psychopathology or greater prosocial behavior.

Social support of the parents, of the chronically-ill children/adolescents and of the siblings, assessed from the perspective of the parents, of the chronically-ill children/adolescents and from the sibling, respectively, by the "Oslo Social Support Scale" (OSSS; Dalgard, 2006). The sum score ranges from 3 to 14. The higher the sum score, the stronger the social support

Coping of the parents, assessed from the perspective of the parents by the German version of the "Coping Health Inventory for Parents" (CHIP-D; McCubbin, McCubbin, Cauble & Goldbeck, 2001). Items are rated on a four-point Likert scale (0 to 3). Higher scores represent greater use of the respective coping pattern.

Family relationships, family dynamics and functionality, assessed from the perspective of the parents, of the chronically-ill children/adolescents and from the sibling, respectively by "Familienbögen" (FB-A; Cierpka & Frevert, 1994). Items are rated on a four-point Likert scale (0 to 3)

familial predispositions assessed from the perspective of the parents by the "Familien-Belastungs-Fragebogen" (FaBel; Ravens-Sieberer, 2001). Items are rated on a four-point Likert scale ranging from 1 (is not right at all) to 4 (is completely right).

Satisfaction with the relationship and parenting relationship of the parents, assessed from the perspective of the parents by the "Partnerschaftsfragebogen" (PFB; Hahlweg, 2016).

Parent-child communication was assessed from the perspective of the child/adolescent and from the perspective of the parents by the "Parent-Adolescent Communication Scale" (PACS; Barnes & Olsen, 1982). Items are rated on a five-point Likert scale.