Sample
Data on the illness cognitions of the parents of a child with cancer were collected in two studies: sample 1 consisted of parents who participated in the period 2006–2009 and sample 2 consisted of parents who participated in the period 2012–2013. The two studies were similar in terms of including the parents of a child diagnosed with cancer and the time since diagnosis (around 1 month, see Table 1). Families in sample 1 completed paper-and-pencil questionnaires, whereas families in sample 2 filled in Web-based questionnaires.
Table 1 Demographic information of participating families
The first sample comprised the parents of children with acute lymphoblastic leukemia (ALL) recruited from six of the seven Dutch pediatric oncology centers (response rate 82 %) [24]. Reasons for non-response were too overwhelmed or medical complications. This study focused on the adjustment of children with ALL during treatment and predictors of child adjustment. Inclusion criteria were age 1.5–18 years, recent diagnosis of ALL, treatment according to the Dutch Childhood Oncology Group (DCOG) ALL 10 protocol [25], and parental fluency in Dutch. The study was approved by the medical ethics review boards of the participating institutions.
The second sample comprised the parents of children recently diagnosed with cancer from four of seven Dutch pediatric oncology centers (response rate 74 %). Reasons for non-response were too overwhelmed, not interested, or medical complications. This study focused on the validation of the Psychosocial Assessment Tool (PAT) and investigated the effects of psychosocial screening in pediatric oncology. Inclusion criteria were age 0–17 years, recent diagnosis of cancer, and parental fluency in Dutch; children with a life expectancy <6 months or a relapse were excluded. The study was approved by the medical ethics review boards of the participating institutions.
The samples were compared regarding child age and gender, and time since diagnosis. The patients in sample 1 were younger (T = −2.25, p = .03), and their parents completed the questionnaires longer after diagnosis (T = 4.30, p = .00) than the patients/parents in sample 2. Patient gender was not significantly different (χ
2 = .78, p = .38).
Measures
Sociodemographic information (diagnosis, family structure, socioeconomic status) was collected with a self-developed questionnaire.
Parental illness cognitions about the disease of their child were assessed with the ICQ-P (adapted from the ICQ with permission from the developers) [26]. See “Appendix” for the questionnaire. The ICQ measures illness cognitions that reflect different ways of evaluating the aversive character of a chronic condition of a patient, namely, helplessness (e.g., “My illness controls my life”), acceptance (e.g., “I can handle the problems related to my illness”), and disease benefits (e.g., “Dealing with my illness has made me a stronger person”). Items are scored on a 4-point Likert scale (1 = not at all, 2 = somewhat, 3 = to a large extent, 4 = completely), and each subscale consists of 6 items. Scale scores are calculated by summing the item scores, resulting in a subscale score ranging from 6 to 24 and a total score ranging from 18 to 72. The text of the questions was adapted to make it appropriate for the parents of ill children. For example, “my illness” in the original questionnaire was changed to “my child’s illness”. The internal consistency of the three scales of the original ICQ ranged from α = .84 to α = .91 [5].
Parental psychological distress (sample 1) was assessed with the Dutch shortened version of the Profile of Mood States (POMS) [27, 28]. The POMS is a self-report questionnaire investigating changeable mood states and consists of 32 items. It is designed to measure mood in five different domains: fatigue (6 items), irritation (7 items), vigor (5 items), tension (6 items), and depression (8 items). The answers are scored on a 5-point scale ranging from “not at all” (0) to “extremely” (4). The reliability and validity of this scale are good (α = .76–α = .95) [27]. In the current study, internal consistency for the different domains ranged from α = .79 to α = .91.
Parental psychological distress (sample 2) was assessed with the Hospital Anxiety and Depression Scale (HADS) [29, 30]. The HADS is a self-report questionnaire assessing the presence of anxious and depressive states in a medical setting. It consists of 14 items in two domains: anxiety (7 items) and depression (7 items). Answers are scored on a 4-point scale, ranging from 0 to 3. The total score is an indication of overall distress (range 0–42). In this study, a cutoff score of ≥13 for the total scale was used to distinguish clinically distressed parents from normally functioning parents [31]. The reliability and validity of this scale are good (α = .71–α = .90) [30]. In the current study, internal consistency for the different scales ranged from α = .82 to α = .91.
Statistical methods
First, the factor structure of the ICQ-P was examined using principal component analysis (PCA) with oblique rotation with a fixed number of three factors, using Statistical Package for Social Sciences (SPSS) version 20. Analyses were first performed separately for the two samples, but results are reported for the combined sample because of the high levels of agreement. Kaiser-Meyer-Olkin Measure of Sampling Adequacy (KMO) and Bartlett’s Test of Sphericity were checked before interpreting the rotated factor loadings. Kaiser recommends a minimum KMO of 0.5 [32]. Each item was assumed to load on one factor only. Factor loadings of 0.36 or higher were considered significant, based on a sample size of 200 [33]. To examine the psychometric properties of the ICQ-P, Cronbach’s alpha was calculated for each subscale; a value of 0.60 or higher was considered acceptable [34]. Pearson correlations were calculated between the three subscales to investigate their mutual relationship. A one-way ANOVA was used to compare scores on the ICQ-P between mothers and fathers and between the different diagnoses (hematological = leukemia and lymphoma; solid = Ewing’s sarcoma, neuroblastoma, rhabdomyosarcoma, Wilms’ tumor, osteosarcoma, and other solid tumors; neuro-oncological = brain/CNS tumor). To test the concurrent validity of the ICQ-P, Pearson correlations between ICQ-P scores and POMS (sample 1) and HADS (sample 2) scores were calculated. To test criterion-related validity, the ICQ-P scores of distressed parents (HADS total score ≥13) and non-distressed parents (HADS total score ≤12) were compared, using a one-way ANOVA. This analysis was performed only with the HADS, which has a validated cutoff point, unlike the POMS. Cohen’s d was calculated as a measure of effect size. P values ≤0.05 were considered statistically significant. Effect sizes .20 were considered small, .50 medium, and .80 large [35].