About one in five minor children has at least one parent with a mental illness [
1]. Mental illness in primary caregivers can impair the psychosocial development of the offspring. The psychological burden of parental mental illness may not only lead to emotional and behavioral difficulties in children, but also has a more general influence on the children’s social relationships, interests, and academic environment, and thus may affect the children’s overall well-being and life satisfaction. Health-related quality of life (HRQoL) has been increasingly considered as an outcome criterion for children and adolescents to determine the burden of such demanding family conditions [
2]. It has been defined as a subjective, multidimensional construct that compromises physical, psychological and social well-being [
3]. Research has consistently shown that HRQoL of COPMI is reduced across different types of parental mental illness [
4,
5,
6,
7,
8]. To prevent adverse psychosocial consequences for COPMI and to improve their HRQoL, it is crucial to examine risk and protective factors that are linked to the children’s well-being. Results can help to develop more efficient clinical interventions. Although self-reports are valuable sources of information, parent proxy-reports are often used as a replacement [
9]. When parents suffer from mental disorders, they tend to assess their offspring’s HRQoL lower than the children do [
10]. Discrepancies between children’s self- and parents’ proxy-reports can also originate from the raters’ relationship and demographic characteristics (e.g., age, gender-identity), as well as from the observability of the HRQoL domain. Investigating the extent of child–parent agreement and to identify predictors of disagreement is crucial, especially when parents are responsible to make health care decisions for their children, and when their perspective on child HRQoL differs from the child’s own rating [
9,
11].
1.1. Predictors of HRQoL in COPMI
The dynamic interaction between both risk and protective factors determines the children’s ability to adapt and recover from adverse psychosocial outcomes associated with parental mental illness [
12,
13,
14]. Some of the most relevant risk and protective factors of HRQoL in COPMI include symptom severity of parental psychopathology and disease coping, emotional and behavioral difficulties in COPMI, the family’s mental health literacy, family functioning, social support, and child-related demographic variables. Parental psychopathology has implications for all family members. COPMI are more likely than their peers to experience unstable home environments, family conflicts, and a higher daily strain [
15]. Depending on the nature and severity of symptoms, parenting skills can be impaired due to psychopathology and may result in reduced involvement with the child, insensitivity, hostility, rejection, neglect, and potential abuse [
15,
16]. Difficulties in parenting can also lead to insecure attachment, emotional dysregulation, negative emotionality, and pathological coping strategies, as well as psychopathology in the offspring irrespective of the children’s age [
16,
17]. Difficulties in parenting have been observed across different types of mental disorders, although most research has been conducted on depression. Parental depression has been associated with a markedly diminished interest in most activities, lack of energy, irritability and depressed mood, which tend to manifest in less child–parent interactions characterized by reduced empathy, verbal communication, and emotional availability, as well as a negative family discord [
18,
19,
20,
21]. The way parents appraise and cope with stressors like mental illness has both an impact on their own [
22,
23] and their offspring’s mental health and quality of life [
24]. Research suggests that parents with a mental illness who practice adaptive coping strategies show better adaptions to their mental health condition [
22], mitigate the negative outcomes of family burden and stigmatization [
25], and improve HRQoL in their offspring [
24].
COPMI have a significantly higher psychiatric risk than children with healthy parents due to various genetic and psychological vulnerabilities [
26]. When children suffer from psychiatric symptoms, quality of life is poor and even lower compared to physical samples [
27,
28]. The World Health Organization (WHO) concluded based on a survey with over 51,507 participants that children with one parent with a mental illness have a 1.8 to 2.9 (odds ratio) times higher general psychiatric risk than the general population. When both parents were affected, the risk even raised from 2.2 to 4.6 (odds ratio) [
29]. COPMI have a seven-fold risk to somaticize [
30] and express psychiatric symptoms by physical complaints like headaches, fatigue, or stomachaches [
8], which lowers satisfaction with physical aspects of HRQoL [
8,
29,
30,
31,
32]. Caregivers’ depressive symptoms also reduce a child’s health-promoting behavior like healthy eating and exercise [
32], which may result in dissatisfaction with physical activities and health. High health literacy in parents, which is characterized by a high amount of knowledge about the recognition, management, and prevention of mental disorders, can serve as a protective factor for the children’s mental health and promote their resilience [
33].
Family functioning is an important determinant of quality of life in children and adolescents [
34,
35,
36]. Research has consistently shown that family burden is higher in families with parental psychopathology across various psychiatric diagnoses e.g., depression [
37], bipolar disorder [
38], psychosis [
39], and anxiety disorders [
40]. Parental psychopathology may be associated with family discord, lower levels of expressiveness and affective involvement, impaired communication [
37,
38,
39,
40], and adverse psychosocial outcomes like unemployment and financial difficulties that strain family relations [
15]. The extent of family burden has been determined by clinical characteristics such as symptom type and severity, a higher relapse frequency, and the severity of impaired functioning [
41].
In line with the stress-buffering hypothesis, social support has been positively associated with HRQoL and psychological well-being and in children and adolescents [
34,
42,
43]. Social support from extrafamilial sources may increase in importance, when family functioning is low. However, especially children from conflict-ridden families had difficulties to find and maintain friends and were viewed less favorably by their peers [
44]. About one third of families with parental psychopathology perceive the social support they receive as insufficient [
30].
The most consistent results regarding child-related demographic predictors of HRQoL exist regarding the children’s age and gender-identity. In a sample with 22,827 European participants, 8–11 years old children reported higher HRQoL than adolescents aged 12–18. Boys reported higher HRQoL than girls in most HRQoL aspects [
45]. Similar age-related decreases in life satisfaction and gender-identity-related differences, especially during adolescence, have been reported in other studies [
6,
8,
46].
1.2. Interrater Agreement on Child HRQoL Measures
Self-reports are generally the principle method with regard to the assessment of subjective experiences of health and well-being [
34]. Nonetheless, it is still common that parents provide proxy-reports on their children’s HRQoL, whereas the children’s perspective is either neglected or surveyed only in addition [
9]. This practice has been justified for younger age groups by the assumption that younger children lack sufficient cognitive and linguistic abilities to understand and interpret HRQoL questions by themselves [
9]. They may also lack the ability to adopt a long-term perspective of events and consequences and have a restricted attention span [
34]. Contrary to these assumptions, studies have demonstrated that even young children, who are given the opportunity to assess their own HRQoL with age-appropriate instruments, are able to understand questions and produce valid and reliable answers from the age of eight years onwards [
47].
Interrater agreement on standardized child HRQoL measures may vary due to child and parent characteristics as well as with the HRQoL domain of interest. Research indicates that the child’s mental and physical health is linked to interrater-agreement on HRQoL measures [
9,
48,
49]. Parents of healthy children over-report the children’s HRQoL compared to parents of children with physical or mental illness [
9,
48,
49]. Parents of children with chronic conditions under-report their offspring’s quality of life [
50]. When children suffer from physical rather than mental illness, child–parent agreement on HRQoL measures is higher [
51], probably due to the better observability of physical symptoms [
9,
49,
52]. Inconsistent results have been reported for child-related age and gender-identity effects on child–parent agreement [
53,
54,
55,
56]. It has been suggested that interrater agreement may vary for certain HRQoL domains like physical or emotional well-being in different developmental stages, thereby explaining the inconsistency [
49].
With regard to the parent’s characteristics, research indicates that the parent’s relationship with the child as well as own perceptions of mental health and HRQoL are more predictive of child–parent agreement than the parent’s sociodemographic attributes. High family functioning characterized by high levels of intimacy and a high amount of shared time increases concordance between children and their parents [
57,
58]. The higher parents assessed their mental health condition [
59,
60] and HRQoL [
11], the higher they rated their children’s well-being too, suggesting that parents project their own feelings on judgments about their children’s functioning [
53]. Parents make more accurate proxy ratings when they assess objective and observable aspects of their children’s well-being (e.g., physical functioning, externalizing behavior) and have more difficulties with subjective and invisible aspects (e.g., the children’s feelings, internalizing behavior) [
45]. The discrepancies reported in emotion-focused HRQoL items appear to become more discordant in adolescence compared to younger age groups [
61], probably because adolescents spend more time in extrafamilial settings and prefer to discuss emotional needs with peers [
49].
There are several research gaps that we aimed to overcome with this study. First, HRQoL has predominantly been investigated in adults with physical or mental disorders, or in normative samples [
8,
62]. Some studies have examined the HRQoL of COPMI but have either based their conclusions on bivariate correlational research, or focused solely on a few risk factors, thereby neglecting the multidimensionality of HRQoL. The inclusion of multiple predictors and regression analyses to draw conclusions on HRQoL in COPMI is still exceptional [
63]. Results from multiple regression analyses may raise awareness for COPMI and allow the development and improvement of appropriate psychological interventions. Second, no study has yet, as far as we know, systematically investigated child–parent agreement regarding the children’s HRQoL when the parents were formally diagnosed with mental disorders according to the ICD-10 classification criteria. Moreover, although research has increasingly considered the children’s perspective in the last two decades, studies have mainly assessed the children’s HRQoL with parent–proxy ratings [
11] and had several methodological limitations [
11,
50]. Small sample sizes have frequently prevented systematic analyses beyond bivariate correlational research, thereby limiting causal inference [
50]. Agreement has usually been assessed with Pearson’s product–moment correlation coefficient, although it is not a measure of agreement [
52,
64]. A more appropriate statistic of agreement would be the intraclass correlation coefficient (ICC) [
65]. In addition, predictors of agreement have rarely been investigated in multivariate analyses, which would enable researchers to glean a more realistic picture of child–parent agreement [
50].
The aims of this study were, therefore first, to compare the HRQoL of COPMI with a reference population, thereby considering the children’s and the parents’ perspective. The second objective is to examine predictors of global child-related HRQoL. The third objective was the investigation of the magnitude and direction of child–parent agreement on specific and global HRQoL. Lastly, we aimed at examining variables predicting (dis)agreement with multiple child- and family-related variables. We expected that children and their parents with a mental illness reported both lower global and specific HRQoL than the reference population. Moreover, we assumed that child and parent psychopathology, low social support, a female gender-identity, older age, family dysfunction, maladaptive coping behavior were associated with lower global HRQoL in COPMI. Furthermore, we hypothesized that child–parent agreement was only of moderate size, and that disagreement on global HRQoL was predicted by child and parental psychopathology, family functioning, parental HRQoL, and the child’s age and gender-identity.