Lung transplantation (LTx) is a life-saving surgical treatment option in terminal-stage respiratory failure (Scheffert and Raza, 2014). Post-LTx survival rates have been reported as 89.1% in the first 3 months, 80% up to a year, 65% in 3 years, 54% in 5 years, and 32% in 10 years (Yusen et al., 2016). Additionally, the median survival duration of LTx recipients (LTRs) was determined to be a little longer than 6 years (Chambers et al., 2018; Yusen et al., 2014). It is clear that LTx provides significant benefits for LTRs in terms of survival. However, the development of chronic lung allograft dysfunction (CLAD) cannot be prevented today in approximately 50% of LTRs (Thabut and Mal, 2017), and the reason for this outcome is still unknown. The cessation of immunosuppressive treatment by LTRs who may think they have completely recovered can be effective in CLAD development. In the literature, there are several studies in which immunosuppressive treatment drug regimen compliance in LTRs has been examined. Organ recipients are supposed to use immunosuppressive drugs at high dosages in the first 2 years and at lower dosages in the following years throughout their lives (Cajanding, 2018a, 2018b).

Despite a distinct improvement in pulmonary functions following LTx (Bartels et al., 2011), a restriction was determined in exercise capacity due to peripheral muscle dysfunction (Braccioni et al., 2020). In contrast, a 1.5- to 2-fold increase is expected in exercise capacity after LTx. In LTRs, postoperative increased forced vital capacity (FVC) and increased forced expiratory volume in the 1st second (FEV1) play an active role in the improvement of pulmonary functions. Nevertheless, increased oxygen consumption and high carbon dioxide production constitute a risk for the exacerbation of pulmonary functions (Bartels et al., 2011). All these problems prepare the ground for LTRs to encounter dyspnea.

Dyspnea develops as a complication in LTRs, and it has various physiological and psychological effects. Anxiety and depression are prominent psychological disorders in chronic lung diseases (Dew et al., 2012; Dew et al., 2023). In a limited number of articles, depression and anxiety have been reported to be the most frequently experienced psychiatric problems (approximately in 30% of recipients) after LTx (Corbett et al., 2013; Corruble et al., 2011; Dew et al., 2012). Depression was associated with mortality and graft loss (Rosenberger et al., 2016). In previous studies, researchers have mostly followed up patients for the first few years following LTx. Therefore, long-term results are quite limited, and the evidence is poor. One of the most important symptoms indicating the exacerbation of pulmonary functions is dyspnea, and as the severity of dyspnea increases, the likelihood of negative emotions may emerge in LTRs. Additionally, this situation may disrupt treatment compliance in LTRs. The objective of this study is (i) to measure the severity of dyspnea experienced by LTRs, (ii) determine the anxiety and depression levels of LTRs, and (iii) investigate immunosuppressive treatment compliance in LTRs.

This study was conducted with a descriptive, correlational, and cross-sectional design to investigate dyspnea, anxiety, and depression levels and immunosuppressive treatment compliance in LTRs.

Table 1 presents the individual characteristics of the participants. The mean age of the participants was 52.60 ± 9.44 years, 56.9% of them were male, 67.7% had moderate economic status, 52.3% were high school graduates, and 80% were married. The results showed that 36.9% of the participants had a history of smoking for 5–10 years, and 4.6% continued to smoke after their LTx. Oxygen support dependency was found in 40% of the participants, and 64.6% used the TriFlo^® II Incentive Spirometer. Hypertension was seen in 32.2% of the participants, and 21.5% had diabetes mellitus (DM). In this study 35.4% of LTRs used Tacrolimus + Mycophenolic Acid (MFA) + Corticosteroid treatment. According to the responses of the participants, 7.7% had stopped using their immunosuppressive drugs without consulting a doctor.

Table 2 presents the mean scale scores of the participants. The mean IDUCS, BAI, BDI, and MBS scores of the participants were determined to be 26.73 ± 8.68, 25.64 ± 9.36, 35.92 ± 9.75, and 2.45 ± 2.12, respectively.

Table 3 shows the results of the comparisons of the IDUCS, BAI, BDI, and MBS scores of the participants based on some of their characteristics. A negative, weak, and significant relationship was found between age and immunosuppressive treatment compliance (p = 0.047). There was a positive, moderate, and significant relationship between age and depression levels (p = 0.006). The female participants had significantly higher BAI, BDI, and MBS scores than the male participants (p < 0.05). In comparison to the participants who had undergone LTx more than 2 years ago, those who had undergone LTx less than 2 years ago had significantly higher IDUCS, BAI, BDI, and MBS scores (p < 0.05). The participants who were smokers and those who were using the TriFlo^® II Incentive Spirometer had significantly higher BDI and MBS scores (p < 0.05). The participants who were dependent on oxygen support had significantly higher BAI, BDI, and MBS scores (p < 0.05).

The results of the correlation analyses of the IDUCS, BAI, BDI, and MBS scores of the participants are presented in Table 4. No statistically significant relationship was found between dyspnea severity and compliance with immunosuppressive treatment (p > 0.05). There was also no significant relationship between compliance with immunosuppressive treatment and anxiety levels (p > 0.05). A negative, moderate, and significant relationship was identified between compliance with immunosuppressive treatment and depression levels (p = 0.007). Positive, strong, and significant relationships were observed between dyspnea severity and anxiety levels (p = 0.016) and between dyspnea severity and depression levels (0.017).

LTRs face psychiatric problems for the first time in the postoperative period. Facing the risk of death, being unable to find a donor, and the possibility of surgical failure in case of finding a donor may cause candidates of LTx to be exposed to high levels of stress, which can result in deterioration in their mental health. The results showed that LTRs experienced moderate levels of anxiety and high levels of depression. The previous studies reported that significant neuropsychiatric symptoms, including depression and anxiety, were observed in LTx candidates (Limbos et al., 2000; Parekh et al., 2003), and the incidence of psychiatric disorders in LTx candidates was 25% (Parekh et al., 2003). Frequently observed psychiatric problems observed in some LTx candidates continue to be experienced after LTx (Wessels-Bakker et al., 2022).

In a previous study, depressive symptoms that persist after LTx in LTRs were associated with mortality (Smith et al., 2014). Similarly, as postoperative anxiety levels in LTRs increased, their rates of physiological problems also increased (Dabbs et al., 2003). Several studies in the literature have shown that depressive symptoms and high levels of feelings of anger-hostility increase the risk of graft rejection in the first 3 years following a heart transplant (Rogal et al., 2013), and depressive symptoms trigger mortality in liver transplant recipients (Dew et al., 1999). Considering the physiological problems resulting from psychiatric problems reported in the literature, the importance of the treatment of depression and anxiety experienced by LTRs in the shortest time possible is clear.

Psychiatric problems experienced by LTx candidates and LTRs and the physiological outcomes of these problems have been analyzed in a limited number of studies in the literature. Although dyspnea appears to be an inevitable symptom in patients with asthma and chronic obstructive pulmonary disease (COPD) (Livermore et al., 2008), it is believed that both state anxiety and trait anxiety are associated with dyspnea development in healthy individuals (Herzog et al., 2018; Sharma et al., 2016). What is worth noting is that high levels of anxiety and depression are seen frequently in dyspneic individuals (Willgoss and Yohannes, 2013), or in contrast, the fear of suffocation and the feeling of breathlessness may lead to depression and anxiety. In this study, dyspnea severity was determined to have separate positive, strong, and statistically significant relationships to anxiety and depression. According to these relationships, as the severity of dyspnea in the participants increased, the severity of their depression and that of their anxiety also increased. In the study conducted by Ricotti et al. (2006) with the participation of 129 LTRs (in postoperative 9th month), the prevalence of dyspnea was reported to be 39%. In this study, 65 LTRs had dyspnea. Of the LTRs included in the sample, 66.1% had undergone LTx more than 5 years ago. Comparing the data of the study by Ricotti et al. (2006) and the data obtained in this study, a longer time after LTx may have increased the severity of dyspnea in LTRs, and they may have quit care practices for healing respiratory functions thinking that they have completely recovered or experienced burnout over time.

Dyspnea is a subjective feeling of restriction and discomfort that occurs as a result of the disruption of the harmony between the afferent information obtained through receptors and the respiratory center and respiratory muscles (Parshall et al., 2012). In the intensive care unit, the prevalence of dyspnea in mechanically ventilated patients was 47% (Schmidt et al., 2011), in recipients was reported as 63% in the early post-LTx period (Sato et al., 2022). In a multicenter study conducted in Italy, the prevalence of dyspnea was recorded as 39% at 9 months after LTx (Ricotti et al., 2006). In our study, 70.8% of LTRs were in the post-LTx period of 1–5 years. The prevalence of dyspnea for the entire sample was 56.9%. None of the recipients in our study reported CLAD. In this study, the mean MBS score of the participants was determined to be 2.45 ± 2.12, indicating that they had mild-to-moderate levels of dyspnea. Dyspnea in LTRs may be related to gradually decreasing functional pulmonary capacity in long-term. In a study conducted with the participation of 21 COPD patients, the same scale as the one used in this study (MBS) was used, and the mean score of the patients was found to be 3.5 ± 2 [moderately to mildly severe] (İnce et al., 2011). Although dyspnea levels in LTRs are usually lower than those in COPD patients, these levels are still worth consideration. This is because in a study previously conducted on COPD patients, it was reported that as dyspnea severity increased, the fear of death also increased (Bülbüloğlu and Kaplan Serin, 2023). In this study, there were LTRs who received the maximum score on MBS, and the rate of those with oxygen support dependency was 40%. Not being able to resolve pulmonary problems after LTx may cause LTRs to experience disappointment. Additionally, just as in COPD patients (Bülbüloğlu and Kaplan Serin, 2023), this situation may cause LTRs to experience the fear of death. This lays the ground for dyspnea to trigger anxiety and depression.

The results showed that 24.6% of the participants did not use their immunosuppressive drugs regularly, and 7.7% quitted taking their medicine without consulting a doctor. The IDUCS scores of the participants were slightly above average. The participants of this study who had been receiving treatment for longer than 2 years had lower levels of adhering to their immunosuppressive treatment (p = 0.035). In some other studies, it has been determined that 21% of renal transplant recipients forget to take their immunosuppressive drugs from time to time (Goldfarb-Rumyantzev et al., 2010) and that 33% are late in taking their medicine on time (Burra et al., 2011). Liver transplant recipients were reported to have relatively high drug compliance levels (Bülbüloğlu and Demir, 2021). In a study conducted with patients within 2 years after LTx, it was determined that 13% of LTRs failed to comply with their immunosuppressive treatment (Dew et al., 2008). The results of this study mostly agreed with the results of other studies in the relevant literature.

In this study, 16.9% of the participants used their immunosuppressive drugs irregularly. LTRs who do not comply with immunosuppressive treatment are undoubtedly at risk of CLAD. There is limited evidence in the literature about compliance with immunosuppressive treatment in patients who have received long-term treatment. In this sense, the findings of this study are very important. However, this study had certain limitations, which included its small sample size, and the data collection tools were self-report scales, the data on some characteristics of the participants were based on their subjective thoughts and feelings. The other limitation principle is that the data were collected online rather than through face-to-face interviews. Therefore, participants were determined online whether they met the inclusion criteria for the sample. The participants were those who volunteered their time, and this may have led to a sample selection bias, which was a limitation. As another limitation, the pulmonary function testing and pre-LTx respiratory examination results of the participants were not analyzed in this study. This situation is related to the fact that it has not been determined whether there is a physiological source of dyspnea. Additionally, hypertension and heart failure, which may have been experienced by some participants, may have triggered dyspnea in them. The severity of depression and anxiety may have been increased by daily problems or situations related to the private lives of the participants.

The immunosuppressive treatment compliance levels of recipients after LTx should be maintained at the maximum level to ensure graft survivability. LTRs and their relatives should continuously be informed and motivated to ensure that their immunosuppressive drug treatment is be maintained at varying doses throughout their lives. The finding in this study that women experienced higher levels of depression, anxiety, and dyspnea in comparison to men suggested that women need more support in this context. The awareness of physicians and nurses in this regard should be raised. The fact that dyspnea experienced by LTRs mostly continued at varying degrees of severity. This situation suggested that more respiratory exercises and interventions that relieve the lungs should be performed. There were also LTRs in this study who used spirometers as well as those who continued to smoke. LTRs should be periodically educated on lung health. As the severity of dyspnea increased, depression and anxiety levels increased as well. Hence, LTRs should be provided with psychological support and psychotherapy.