Background
Congenital heart disease (CHD) occurs in 4–12 per 1,000 live births [
1,
2]. More than one third of the affected children are born with "critical heart disease" denoting malformations, which acutely threaten life and necessitate palliative or corrective surgery in early life [
3]. Advances in surgical and postoperative support techniques have significantly reduced the mortality and have lead to acceptable mid- and long-term cardiac outcome even for children with complex CHD, premature or low-birth-weight children [
4‐
8]. Various risk factors for long-term morbidity have been identified. Particularly, cardiopulmonary bypass surgery is associated with inflammatory responses, renal, myocardial, and neurological injury [
9] and may consequently lead to neurodevelopmental impairments [
10,
11]. While open-heart surgery can correct or palliate CHD, it also represents the challenge of psychologically adjusting to the surgical event and associated side effects for the child and the parents. Moreover, the question arises as to how quality of life in these patients is affected by the surgical event.
There is an increasing body of literature addressing these questions. Many studies have examined neuropsychological functioning, behavior and quality of life in children and parents. However, methodological shortcomings make it difficult to compare studies. They vary greatly in study design, inclusion criteria, assessment of risk factors, duration of follow-up, attrition and in particular in outcome measures. Thus, a systematic review of the existing literature is needed to summarize the evidence on psychological outcome and quality of life and the pertinent risk factors.
To facilitate the understanding of this review, the relevant terminology is briefly introduced: The assessment of
psychological adjustment incorporates a range of outcome measures including behavioral, emotional or psychosocial constructs. A common approach differentiates between internalizing and externalizing behavior difficulties [
12]. The former are characterised by symptoms of anxiety, depression, and withdrawal, while the latter include delinquent, aggressive, and show off behavior.
Quality of life (QoL) is a multidimensional construct integrating an individual's subjective perceptions of physical, social, emotional and cognitive functioning [
13]. In the context of patient populations this is referred to as health-related quality of life. Traditionally, QoL in cardiac patients has been estimated by objective indices related to health outcomes such as cardiopulmonary exercise capacity [
14], exercise tolerance [
15], or the New York Heart Association classification. However, meanwhile there is a general agreement that these indices alone do not suffice to reflect QoL in cardiac patients in all its facets [
16].
Psychological adjustment and QoL can be assessed by means of self- or proxy-reports. Generic as well as disease-specific assessment instruments exist. The former are used with any patient population independent of their disease, while the latter assess disease-specific issues. Some instruments combine generic with disease-specific items.
This review aims to systematically assess studies on psychological adjustment and QoL in children and adolescents with CHD undergoing cardiopulmonary bypass surgery. Also, associations between medical, individual and familial risk factors and the long-term outcome were evaluated.
Discussion
This review is the first to systematically summarize the literature of the last 18 years on psychological adjustment and quality of life of children and adolescents with CHD following cardiopulmonary bypass surgery. Moreover, potential risk factors for psychological maladjustment and impaired quality of life are reported.
Proxy-reported long-term outcome
Studies assessing the incidence of psychiatric diagnoses, although few, as well as studies investigating the rates of clinically significant behavioral symptoms have demonstrated that a considerable proportion of these children experience psychological maladjustment according to their parents. The observed proportion of children with a psychiatric diagnosis [
18,
19] is comparable to children with other chronic illnesses, who have a two-fold higher risk than children in the general population [
51,
52]. Likewise, significantly more children with operated defects displayed behavior outside a normative range [
21,
22,
24,
30,
35]. In the same line, studies assessing mean levels of psychological functioning found significantly more psychological difficulties in operated children compared to controls [
21,
23,
24,
33,
35,
37,
40]. As an exception, parents of children with surgically corrected transposition of the great arteries consistently reported good or even better psychological adjustment [
31,
32,
41] than controls. This good outcome may be due to the excellent prospect of correcting this malformation by means of arterial switch operation. A lower rate of genetic disorders in this subgroup of patients may also contribute to this favorable outcome. As the latter findings originated from the same institution and are partly based on overlapping samples, they need to be confirmed by other groups.
Interestingly, teachers judged the behavior and functioning of children with CHD similar to that of control children [
21,
22]. Although these findings need replication, they point out the discrepancy between parental reports and teacher reports. The results indicate that the children's difficulties are less apparent within the schooling context. This may be due to the fact that children are reported to show predominantly internalizing problems, which are less likely to be detected by teachers than by parents. Alternatively, this result may highlight the importance of the negative influence of parental anxieties with regard to their subjective perception of their children.
Self-reported long-term outcome
To date, there are only few studies that assessed self-reported psychological adjustment in children after cardiopulmonary bypass surgery. Thus, available results do not allow for a final conclusion but provide further directions of research. Three studies did not find differences in self-reports of children with operated heart defects compared to a reference group, thus contrasting proxy reports [
18,
23,
34]. The divergence between parents and their children (and teachers), the so-called cross-informant variance, has frequently been reported across different clinical samples [
53]. It may reflect differing, yet equally important, realities [
54] and highlights the need for outcome assessments using multiple informants. Only two studies observed a significant degree of self-reported behavioral difficulties [
35,
36]. Since the study by Utens et al. comprised a large proportion of adolescent cases, this finding does not contradict other results that are based on self-reports in children. Yet, it may indicate a decline in psychological adjustment associated with the onset of puberty and the increasing academic demands. Clearly, more research is needed to confirm these findings.
Quality of life
Current data suggest that children with CHD undergoing cardiopulmonary bypass surgery may be faced with an impaired QoL at follow-up [
45‐
48]. Impairments are more frequently reported by parents than by the patients themselves. Notably, in 4 of the 12 reviewed studies, a normal QoL was found. Children with operated transposition of the great arteries may be overrepresented in the reviewed studies as most samples comprised children with this defect only [
24,
41,
44] or included a subsample of these children [
43,
48]. Thus, findings may not be applicable to the remaining population of children with CHD.
Risk factors for long-term outcome
To date, there is insufficient and conflicting data to attribute long-term outcome to the various risk factors assessed. As only few studies evaluated the same risk factors, findings are preliminary and demand replication. Moreover, the evaluation of risk factors often did not adhere to strict statistical standards, i.e., by adjusting for confounding variables by means of multivariate analysis.
The cardiac diagnosis does not seem to be a particular risk factor for psychological maladjustment after cardiopulmonary bypass surgery. This has been demonstrated in numerous studies across different ages [
26,
29,
35,
37‐
39,
41,
45]. Nevertheless, physical correlates of the heart defects (such as cardiac insufficiency mandating cardiac medications or arrhythmias during follow-up) or other physical problems such as pulmonary problems may lead to reduced
proxy-reported psychological adjustment and QoL [
19,
23,
45‐
47]. Such a relationship was not detected for child self-reports [
18,
23].
While surgery itself may pose a risk for long-term outcome, current research has attempted to assess the effects of various organ support techniques, duration of surgery [
24,
32,
39‐
41,
44,
45] and length of hospital stay [
45]. However, potential confounders such as depth of hypothermia or postoperative complications must be carefully controlled for before a conclusion can be derived. Likewise more data are needed addressing the conflicting current findings.
Developmental delay is a child-specific risk factor that has consistently been found to relate to
proxy-reported psychological maladjustment following heart surgery [
24,
32,
35,
37,
41]. Thus, parents of children with language difficulties or cognitive delay reported more psychological difficulties in their children. In contrast, this association was not found for self-reported psychological adjustment. Other risk factors such as sex, education or socioeconomic status have rarely been investigated.
Finally, the parents of children with operated heart defects themselves may play an important role with regard to the child's long-term psychological adjustment [
23,
31] and quality of life [
43,
45,
46]. However, more research is needed to further evaluate the role of parental adjustment for the long-term outcome and QoL in their children. Also, the causal rather than the correlational nature of this relationship warrants empirical support.
Limitations and implications for future research
With regard to the methodology of the reviewed studies, several limitations were identified. Only four out of 35 studies were found to be of high methodological quality according to a self-developed rating system. All but one study [
31] applied a cross-sectional or retrospective design. This approach does not allow to describe the dynamic course of psychological adjustment or QoL in relation to surgery. Neither does the use of normative data or healthy control groups suffice to causally attribute group differences to the surgical procedure itself; they may be associated with the chronic disease itself [
41,
47]. Thus, a control group design should account for
a) the effect of a high-risk surgical intervention, and
b) the effect of living with CHD. Even if these standards are met, results still need to be discussed in the light of potential confounding, i.e., less severe illness in controls.
In this systematic review, we did not include studies that only focused on children with chromosomal anomalies. However, we did not find a study that only addressed this subgroup. The reviewed studies typically excluded patients with chromosomal anomalies and non-cardiac comorbidities. Because cardiac defects frequently result from chromosomal disorders and because neurological disability is one of the major risk factors associated with cardiopulmonary bypass surgery, the exclusion of such patients may have biased findings towards better outcome. Thus, less restrictive exclusion criteria and the systematic use of subgroup analysis will allow to determine QoL and psychological adjustment in these children.
Other limitations relate to the operationalization of outcome variables. As most studies assessed psychological adjustment by means of the Child Behavior Checklist [
12] well-known shortcomings of the scale within the context of chronic disease must be addressed [
55]. While this instrument has been validated for a psychiatric population, its suitability for chronically ill children is unclear. The optimal assessment instrument should allow for a clear distinction between symptoms primarily associated with the disease and those associated with consequences of the disease validated for the target population. To the best of our knowledge, no such scale exists for the assessment of psychological adjustment in children with chronic diseases. In contrast, such progress has been made with regard to the psychometric assessment of quality of life. Recently, the PedsQL [
56] has been supplemented with a cardiac module [
57], and is currently under validation. In addition, a large US research group has published the Pediatric Quality of Life Inventory (PCQLI), which is a disease specific QoL measure for children with CHD [
50]. The PCQLI has patient and parent-proxy forms, covers a wide age range and showed very promising data in the multi-center validation study. Certainly, future studies on QoL in children with CHD should incorporate these new disease specific measures.
Conclusion
This review demonstrated that a significant proportion of children with CHD experience psychological maladjustment following cardiopulmonary bypass surgery. Children with more severe heart defects, or those in need of future surgical interventions and children with neurodevelopmental impairment are at particular risk for maladjustment. The QoL of these children appears also to be affected, particular with regard to parental reports. However, the literature on this important outcome is still emerging and disease-specific instruments have just been published. Importantly, parental well-being seems to be related to psychological adjustment in these children. This calls for an integrated approach to family support, taking the child's individual needs into account as well as the needs of the parents.
Competing interests
The authors declare that they have no competing interests.
Authors' contributions
BL and MAL participated in the selection and review of studies and the writing of the manuscript. SH participated in the selection and review of studies and drafted the manuscript. JEF and UB participated in the interpretation of findings and critically reviewed the manuscript. All authors read and approved the final manuscript.