A systematic review of psychological interventions in adults with pulmonary hypertension: Is the evidence‐base disproportionate to the problem?

Abstract Introduction Our understanding of the psychological impact of living with pulmonary hypertension (PH) is growing, particularly for how anxiety and depression present in this group. There is evidence for the use of psychological interventions in other chronic lung conditions; however, trials focusing on adults with PH have yet to be subject to a systematic review. Methods We systematically searched four databases for evidence examining the effectiveness of psychological interventions for adults with PH. A narrative approach has been used to present findings. Results Overall, 186 unique articles were identified of which four were suitable. Data was gathered from 143 individuals. Cognitive behavioural therapy (CBT), metacognitive therapy (MCT) or counselling were investigated. All three studies reported a significant reduction in anxiety and depression, and some secondary outcomes were also associated with change. Discussion The evidence supporting the use of psychological therapies for adults with PH is promising, although limited. There is an urgent need for more research in this area to better understand how we can support this clinical group.


| BRIEF REPORT
Pulmonary hypertension (PH) is a group of serious and life-limiting conditions. 1 Research into PH has primarily focused on reducing early mortality and morbidity rates, and it is only recently that the psychological, emotional and social impact of PH has been more extensively examined. Symptoms associated with anxiety and depression, which have also been shown to be correlated with health-related quality of life in people with PH, 2,3 appear to have received the greatest attention. Rates of mood disorders have been described as alarming, with observed figures being considerably high (rate of depression: 95% CI: 20.5%-36.8%; anxiety: 95% CI: 28.7%-46.4%). 4 Our understanding of how anxiety, depression and other psychological difficulties interact with PH-related symptoms is currently developing. The available studies indicate that disease specific factors alone are unable to fully account for the reported impact [5][6][7] with physiological measures of functioning tending to be non-significant risk factors for depression or anxiety. 4 There is also a need for studies to identify the underlying psychological mechanisms implicated in adjustment to living with the condition. This would enable the development of targeted psychosocial interventions that are likely to be effective in reducing the impact of living with PH.
There is some evidence for the use of psychological therapies for anxiety and depression in people with other chronic lung conditions. 8 Unfortunately, the availability of such interventions in people with PH appears to be limited. 9 Further, whilst several studies exist, they have not been subject to a systematic review, with previous attempts to review psychological interventions failing to utilise appropriate review methods 10,11 or including nonpsychological interventions. 4 We report on our systematic review of the evidence examining the effectiveness of psychological interventions for adults with PH.
We performed a systematic search in February 2023 of four databases: PsycINFO, MEDLINE, Cochrane library and CINAHL. Search terms were informed by relevant articles known to the authors 12,13 (Table 1). Inclusion and exclusion criteria are reported in Table 2. Studies were included if they examined any patientreport outcome measure in response to a psychological intervention. Participants must have been adults (>18 years) and diagnosed with any form of PH.
Title and abstract of articles identified were first screened. Most studies were excluded at this stage as they did not investigate PH or were not evaluating a psychological intervention. If relevant, articles were then subject to a full-text review. Forward and backward searchers of included articles were performed, including searches for articles in previous reviews, 4,10 which generated one additional study ( Figure 1).
Relevant data based on participant, intervention, comparison group and outcome (PICO) were extracted from each article (see Table 3). Given the small number of studies and heterogeneity in research methods, a narrative approach was deemed as most suitable to present the findings.
Four studies were identified as suitable ( other included all forms of PH. Participants were judged to be representative of the target population; three samples were recruited from hospital settings in Europe, and the other was an international study recruiting adults from the community. Cognitive behavioural therapy (CBT), 12,14 metacognitive therapy (MCT) 15 and unspecified counselling 13 were evaluated using a pre-and post-intervention design; two studies provided a follow-up (4 and 6 weeks). Interventions focused on self-reported outcomes including, anxiety (CBT), anxiety and depression (unspecified counselling), and adjustment disorder (MCT). However, one intervention reported their primary endpoint was change in peak oxygen consumption (peak VO 2 ); suggesting changes in mental health were a secondary aim. 14 Three studies used interventions delivered by a healthcare professional, the other was a self-help programme. Only one study reported how treatment adherence was assessed in patients; no study reported on therapists' adherence to treatment modality.
Two studies included a control group; the other studies were an observational trial or a case study. All studies measured anxiety and depression; other health-related measures and psychological processes were also assessed. Although for the most part measures were appropriate given the research aims, it is important to recognise that they were typically screening tools and did not aim to diagnose individuals.
A significant reduction in anxiety and depression was observed in all samples. There was some evidence to suggest anxiety and depression did not improve in people with PH who did not receive a psychological intervention. 12,13 Change in self-perceived health status including quality of life was also observed. 13,14 Improvement in psychological mechanisms that are considered to underlie difficulties with mental health was observed in two studies-cognitive and behavioural process 5 and metacognitions. 15 This appears to be consistent with findings reported elsewhere, 2,5,7 which have demonstrated psychological processes that are related to subjective F I G U R E 1 Prisma flow diagram.
T A B L E 3 Summary of studies examining patient-reported outcomes in adults with PH in response to psychological interventions.  measures of wellbeing and therefore a possible target for intervention. This has included coping styles, cognitions, behaviours and self-compassion. Any changes in patient reported outcomes were also maintained at follow-up.

Author
Although not all self-reported outcome measures were associated with significant change, including dyspnoea, which is a cardinal symptom of PH, they should only be viewed as secondary outcomes as interventions did not target them specifically. Individuals who scored a greater severity of symptoms were more likely to engage in therapy 13 and less likely to drop out. 12 It may be that this group have more of a need for psychological intervention and motivated to engage. Two studies reported on attrition demonstrating a relatively low rate of 18.9% 12 and 6% 14 in those receiving CBT. Indeed, there is limited evidence on the acceptability of mental health support in people with PH; a qualitative study interviewing 24 individuals with PAH found some were not open to receiving support. However, counselling or therapy was wanted by those reporting difficulties with coping with their worries and emotions, as well as individuals who received limited support from others or experiencing additional life challenges. 16 The importance of integrating treatments for physical and mental health has long been recognised. 17 A large body of evidence exists highlighting the reciprocal relationship between physical and mental health, acknowledging that living with a long-term health condition is associated with higher prevalence of mental health problems. Similarly, those with psychological problems, including anxiety and depression, are more likely to experience difficulties managing their health conditions; however, this has yet to be examined in people with PH. Provision of targeted psychological support integrated within health care services is therefore essential for improving outcomes.
Advancements in how PH is diagnosed and treated have resulted in people living longer with the condition. There is now a need to extend treatment beyond the physical symptoms, as research has shown this group are significantly impacted by the condition. 3,18 Although the increased risk of mood disorders in this clinical group is well recognised, the evidence for treating such psychological distress using therapy is limited. It is clear that more research is needed to help address the gap between the problem and evidence-base. Although data gathered from research trials are important, evidence collected from routine clinical practice are essential in helping to build the evidence. In addition to using patient reported outcomes, research should focus on patient's experiences of engaging in psychological treatments. This information can be used to glean insight into the acceptability and feasibility of interventions and improve many aspects of treatment. This is the first systematic review examining psychological interventions for emotional difficulties in people with PH. It is a limitation that a narrative approach was used to synthesise the results; however, at this time, due to the limited data and heterogeneity in methods, samples, interventions and measures, a meta-analysis would not be appropriate. Articles were screened and data were extracted by one researcher whereas steps could have been taken to protect against bias and human error. Despite this, the evidence is promising for the use of such therapies, but importantly, also highlights the urgent need for more research and better patient involvement and access.
AUTHOR CONTRIBUTIONS Gregg H. Rawlings developed the concept of the review. He developed the protocol, performed the systematic review, data extraction and analysis and write up. He approved the final manuscript for submission. Barbora Novakova was involved in the concept of the review. She provided feedback on an earlier version of the review and approved the final manuscript for submission. Iain Armstrong was involved in the concept of the review. He provided feedback on an earlier version of the review and approved the final manuscript for submission. Andrew R. Thompson was involved in the concept of the review. He provided feedback on an earlier version of the review and approved the final manuscript for submission.

DATA AVAILABILITY STATEMENT
Data sharing is not applicable to this article as no new data were created or analyzed in this study.

ETHICS STATEMENT
Ethical approval was not required for this article and therefore was not obtained.