http://orcid.org/0000-0001-8539-8131
Abstract
Psychological factors such as negative affect have been demonstrated to impact course and treatment of chronic obstructive pulmonary disease (COPD). However, little is known about the respective impact of social factors. In several other chronic diseases, loneliness has been shown to predict morbidity, but little is known about its impact on COPD. Therefore, this study examined the associations between loneliness and outcome measures of a pulmonary rehabilitation program (PR). Before and after a 3-week inpatient PR program, patients with COPD (N = 104) underwent a 6-min walking test to measure functional exercise capacity. Loneliness was assessed with the Loneliness Scale. The Medical Outcomes Study 36-item short form, 9-item Patient Health Questionnaire, and 7-item General Anxiety Disorder questionnaire were administered as measures of health-related quality of life (HQoL), depression, and anxiety, respectively. Multiple regression analyses showed that at the start of PR, more loneliness was associated with worse levels of functional exercise capacity, HQoL, depression, and anxiety, but with greater improvements in functional exercise capacity and HQoL over the course of PR, even after controlling for age, sex, lung function, and smoking status. Patients with stronger decreases in loneliness from start to end of PR showed stronger improvements in functional exercise capacity and HQoL over the course of PR. The present study shows that subjective loneliness is associated with relevant treatment outcomes in patients with COPD undergoing pulmonary rehabilitation. Therefore, loneliness should be addressed in patients with COPD as it could play a significant role in their disease progression.
| Abbreviations | ||
| 6MWD | = | six minute walking distance |
| 6MWT | = | six minute walking test |
| ANOVA | = | analysis of variance |
| ATS | = | American Thoracic Society |
| COPD | = | chronic obstructive pulmonary disease |
| DJGLS | = | De Jong Gierveld Loneliness Scale |
| ERS | = | European Respiratory Society |
| FEV1 | = | forced expiratory volume in 1s |
| FEV1%pred | = | forced expiratory volume in 1s in % predicted |
| GAD-7 | = | Generalized Anxiety Disorder-7 |
| GOLD | = | Global Initiative for Chronic Obstructive Lung Disease |
| HQoL | = | health-related quality of life |
| LTOT | = | long-term oxygen therapy |
| PHQ | = | Patient Health Questionnaire |
| PHQ-9 | = | Patient Health Questionnaire-9 |
| PR | = | pulmonary rehabilitation |
| SF-36 | = | 36-Item Short Form Health Survey |
| VC | = | vital capacity |
Introduction
Chronic Obstructive Pulmonary Disease (COPD), a common preventable and treatable disease, is characterized by persistent airflow limitation that is usually progressive and associated with an enhanced chronic inflammatory response in the airways and the lungs to noxious particles or gases (Citation1). COPD is associated with significant individual, social, and economic burden and considerable reductions in patients’ health-related quality of life (HQoL) (Citation1).
Besides the prominent pulmonary symptoms, patients with COPD often suffer a wide array of somatic (e.g. lung cancer, hypertension, diabetes) as well as psychological co-morbidities (Citation2). For example, depression and anxiety are prevalent in patients with COPD and are related to a worse course of disease including reduced HQoL and functional capacity, and increased symptom burden and mortality (Citation3–6). Multidisciplinary pulmonary rehabilitation (PR) including intensive physical exercise training is the single most effective treatment for COPD with proven beneficial effects on symptoms, functional capacity, HQoL, anxiety, and depression (Citation7,Citation8).
If untreated, pulmonary symptoms and somatic as well as psychological co-morbidities can severely restrict patients’ activities leading to fewer social contacts, loss of a normal social life (Citation9) and in severe cases cause patients to be homebound and even chair bound (Citation10,Citation11). This can result in feelings of isolation and loneliness (Citation9,Citation12–14). Indeed, loneliness has been reported to be common in patients with COPD (Citation15–18). However, potential interactions of loneliness with treatments and clinical outcomes in COPD patients remain widely unknown.
In contrast, previous research on several other chronic diseases such as chronic heart disease, ischemic stroke, and obesity has impressively demonstrated that loneliness is not only highly prevalent in these patients but also associated with a worse course of these diseases (Citation19–24). For example, among older adults, loneliness was related to poorer clinical outcomes in those with heart disease (Citation25). Moreover, in a 5-year follow-up, patients with stroke who were more lonely were more likely to suffer a recurring event (Citation26). Loneliness is even associated with increased mortality with an increased risk of death over 5 years of 40% for lonely patients with stroke and of 123% for lonely patients with chronic heart disease compared to non-lonely patients (Citation26,Citation27).
It is important to note that loneliness is not necessarily the same as being socially isolated. Rather, loneliness can be classified into a more quantitative, social loneliness (i.e., absence of a social network or friends) and a more qualitative, emotional loneliness (i.e., absence of a close, intimate attachment to another person) (Citation28). Especially emotional loneliness has been suggested as being the critical determinant of negative health outcomes (Citation29,Citation30).
The present study examined in patients with COPD the relationships between loneliness and outcomes of an inpatient pulmonary rehabilitation (PR) program. Specifically, we tested the hypothesis that emotional loneliness would be associated with less favorable results in functional capacity, HQoL, and psychological co-morbidities both cross-sectionally and prospectively.
Materials and methods
Patients
We tested 104 consecutive patients with COPD who completed a 3-week inpatient PR program at the Centre for Rehabilitation, Pneumology and Orthopedics (Clinic Bad Reichenhall, Germany). This sample is a subgroup analysis of the RIMTCORE study (Citation31). Anamnesis and diagnosis were performed by pulmonary physicians according to GOLD criteria (Citation1). Forced expiratory volume in one second (FEV1%pred) and vital capacity (VC) were determined by spirometry and body plethysmography (Masterlab, CareFusion, Hoechberg, Germany) according to ATS/ERS criteria (Citation32). Inclusion criteria were a diagnosis of COPD according to GOLD criteria, and the ability to read and understand German. Study approval was granted by the local ethics committee (Bayerische Landesärztekammer, No. 12107). All patients provided written informed consent.
Pulmonary rehabilitation
Tailored to the patients’ individual needs, the PR program consisted of various modalities including endurance and strength training, muscle training, patient education, respiratory physiotherapy, bronchial drainage, smoking cessation, initiation of long-term oxygen therapy and/or noninvasive ventilation, psychological support, and nutrition counseling. Details can be found in Schultz et al. (Citation31).
Measurement of functional exercise capacity
At the start and end of PR, subjects performed the 6-min walking test twice (6MWT) according to ATS recommendations (Citation33). The largest distance of the two tests was used for analysis. The total distance walked in 6 min (6MWD) was the primary outcome.
Measurement of loneliness
Subjectively experienced loneliness was assessed with the German version of the De Jong Gierveld Loneliness Scale (DJGLS), which is a widely used and validated self-administered questionnaire (Citation34). The eleven items measure social loneliness (i.e., lack of social integration and embeddedness, five items), and emotional loneliness (i.e., lack of a specific, intimate relationship, six items). Scores on the social and emotional loneliness subscale range from 0–20 and 0–24, respectively with higher scores indicating higher levels of loneliness. Total scores of 2, 8, 10, and 11 represent cut-off values for no loneliness, moderate, severe, and very severe loneliness, respectively.
Measurement of anxiety and depression
Anxiety and depression were measured using The Patient Health Questionnaire (PHQ). The module measuring depression (PHQ-9) is composed of nine questions based on the DSM-IV criteria for major depressive episode, with a total score ranging from 0 to 27 (35). The seven item module GAD-7 assesses levels of general anxiety with a total score ranging from 0 to 21 (36). Higher scores indicate higher levels of depression and anxiety. Both questionnaire modules show good reliability and validity (Citation35,Citation36).
Measurement of health-related quality of life
Health-related Quality of Life (HQoL) was assessed in the present subsample of the RIMTCORE cohort with the widely used 36-Item Short Form Health Survey (SF-36) (Citation37), which has shown satisfactory validity and reliability in COPD patients (Citation38). Thirty-six items assess eight subdomains of HQoL (vitality, physical functioning, bodily pain, general health perceptions, physical role functioning, emotional role functioning, social role functioning, and mental health). The subdomains are subsumed into a physical and mental summary score (range: 0–100), with higher scores reflecting higher HQoL.
Data analysis
Data are presented as mean (±SD) unless otherwise indicated. Changes in outcome measures from pre to post PR were analyzed with repeated-measures ANOVA. Hierarchical linear regression models were used to examine the relationships between loneliness and functional capacity, HQoL, general anxiety, and depression at the start of PR (=cross-sectional) and for changes (post-PR–pre-PR) in these variables over the course of PR (=prospectively). Analyses were run separately for the subscales emotional and social loneliness and controlled for potential effects of age, gender, lung function (FEV1%predicted), and smoking status. We performed a post hoc bootstrap analysis (1000 samples) to test the robustness of the models. Analyses were conducted using SPSS 24 (39) using p < .05 as the level of significance.
Results
Patient characteristics
presents the demographic and baseline characteristics of the patients. The sample (70% men) consisted of patients with mild-to-very severe COPD stage according to GOLD criteria (Citation1) with a mean FEV1%predicted of 45.4%. Of all patients, 30% suffered from clinically relevant depression and 24% from clinically relevant anxiety. About 46% of patients experienced moderate-to-very severe loneliness.
Table 1. Baseline sample characteristics.
Outcomes of pulmonary rehabilitation
As presented in , patients showed improvements in most outcome measures. Functional capacity (6MWD) increased significantly over the course of PR (p < .001). Moreover, HQoL improved during PR as indicated by increases in the physical and mental summary scores of the SF-36 (p < .001; p < .01). Furthermore, levels of depression and anxiety showed significant decreases after PR (p < .001; p < .001). Emotional loneliness (pre-PR: M = 10.70, SD = 5.32; post-PR: M = 10.94, SD = 4.92) and social loneliness (pre-PR: M = 8.36, SD = 2.79; post-PR: M = 8.05, SD = 2.66) showed no significant changes across the whole sample between the start and end of PR (p = .525 and p = .205).
Table 2. Mean (SD) outcome measures at the start and end of PR.
Influence of loneliness on pulmonary rehabilitation outcomes
Cross-sectional regression analysis controlling for potential confounding effects of age, sex, FEV1% predicted, and smoking status showed that higher emotional loneliness at the start of PR was a significant predictor of reduced functional capacity and mental HQoL as well as increased levels of general anxiety and depression at the start of PR (, ). A one point increase in emotional loneliness corresponded with a decrease of 3.91 m in the 6MWT and 1.32 points in the SF-36 mental summary scale. The PHQ-9 (depression) and GAD-7 (anxiety) increased by 0.61 and 0.51 points, respectively with each one point increase in emotional loneliness. Social loneliness at the start of PR was not significantly associated with any of the outcome measures at the start of PR.
Figure 1. Impact of emotional loneliness on outcomes at the start of PR. (A) Association of emotional loneliness with functional capacity at the start of PR. (B) Association of emotional loneliness with quality of life at the start of PR. (C) Association of emotional loneliness with depression at the start of PR. (D) Association of emotional loneliness with anxiety at the start of PR.
Table 3. Association of emotional loneliness with outcome measures at the start of PR.
Prospective regression analysis showed that higher emotional loneliness at the start of PR predicted greater improvements in functional capacity and mental HQoL during PR, even after controlling for age, sex, FEV1%predicted, and smoking status (). A one point increase in emotional loneliness corresponded with an increase of 3.06 m in change scores in the 6MWT and of 0.41 points in the SF-36 mental summary scale. Emotional loneliness at the start of PR was not associated with changes in physical HQoL, general anxiety, and depression during PR (). Higher social loneliness at the start of PR only predicted greater improvement in physical HQoL during PR. Furthermore, changes in emotional loneliness during PR were a significant predictor of changes in functional capacity and mental HQoL, even after controlling for age, sex, FEV1%predicted, and smoking status (, ). Specifically, patients whose emotional loneliness decreased more showed greater improvements in functional capacity and mental HQoL. A one point decrease in change scores in emotional loneliness corresponded with an increase of 4.21 m in change scores in the 6MWT and of 0.65 points in the SF-36 mental summary scale. Changes in emotional loneliness were not associated with changes in physical HQoL, general anxiety, and depression (). Finally, stronger decreases in social loneliness predicted greater improvement in physical HQoL during PR.
Figure 2. Impact of changes in emotional loneliness on changes in outcomes of PR. (A) Association of changes in emotional loneliness with changes in functional capacity over the course of PR. *Excluding the outlier patient did not change the results. (B) Association of changes in emotional loneliness with changes in quality of life over the course of PR. *Excluding the outlier patient did not change the results.
Table 4. Association of emotional loneliness at the start of PR with changes in outcome measures during PR.
Table 5. Association of changes in emotional loneliness with changes in outcome measures during PR.
Additional explorative post hoc bootstrapping analysis (1,000 samples) for cross-sectional and prospective data yielded widely comparable results to the regression analyses.
Discussion
The present study examined the relationships between loneliness and outcomes of a 3-week inpatient pulmonary rehabilitation program in patients with COPD both cross-sectionally and prospectively. As expected, pulmonary rehabilitation had beneficial effects with significant improvements in functional capacity, HQoL, anxiety, and depression, which underlines the established importance of PR as single most effective treatment for COPD (Citation8,Citation40–45). Notably, we observed a very high prevalence of loneliness in the studied patients. Most importantly, emotional loneliness was associated with less favorable outcomes including reduced functional capacity and HQoL, and increased levels of anxiety and depression cross-sectionally but with improved functional capacity and HQoL prospectively. A decrease in emotional loneliness was associated with improved functional capacity and HQoL prospectively. Together, these results suggest an important clinical role of loneliness in COPD.
Our cross-sectional observation of higher emotional loneliness being associated with worse outcomes in patients with COPD at the start of PR converges with various previous findings in patients with other chronic diseases (Citation19–26). Together, these studies similarly demonstrated a less favorable clinical status in patients with high levels of loneliness. For example, Tomaka et al. (Citation25) showed that among older adults, loneliness was related to a higher risk for developing chronic heart disease. Similarly, in a study by Whisman (Citation20), loneliness was associated with increased likelihood for meeting the criteria for metabolic syndrome. The specific mechanisms linking high levels of emotional loneliness with worse outcomes in COPD patients remain unclear from the present study. However, multiple mechanisms seem plausible. For example, Hawkley et al. (Citation46) showed an association of loneliness with less effort towards maintaining and optimizing positive emotions in older adults. In turn, this can reduce an individual’s likelihood of performing positive health behaviors (Citation47,Citation48), including physical activity (Citation46), and lead to diminished HQoL (Citation49). This positive emotion flattening has also been observed in patients with depression and anxiety (Citation50) suggesting a possible link between loneliness and more negative affect (i.e., depression) and subsequent detrimental effects on functional capacity and HQoL (Citation17).
Similarly, our prospective observations of significant associations between emotional loneliness and outcomes over the course of PR in COPD patients are in line with several other studies, demonstrating prospective associations of loneliness with chronic disease outcomes (Citation23,Citation24,Citation26). For example, Boden-Albala et al. (Citation26) showed that over a 5-year follow-up period, pre-stroke social isolation predicted post-stroke outcome events. Moreover, Thurston et al. (Citation23) demonstrated that loneliness was prospectively associated with increased risk of incident coronary heart disease over a 19-year follow-up period. In the present study, increases in emotional loneliness over the course of PR were associated with smaller improvements in functional capacity and mental HQoL, whereas stronger decreases in emotional loneliness were associated with greater improvements in these outcomes. A potential underlying pathway could be the beneficial social opportunities that PR provided to many patients, especially to those with initially high levels of loneliness, which showed the highest improvements during PR. Following this lead, in a qualitative study by Halding et al. (Citation51), patients with COPD described social integration and support as an important and positive part of PR that enhanced their quality of life. The formation of new social networks provided them with chances for integration with engagement, commonality, and role-identification as well as resources to enhance their ability to cope with the stress of chronic illness. This might contribute to improvements in both HQoL and motivation to engage in exercise. Furthermore, higher emotional loneliness at the start of PR predicted greater improvements in functional capacity and mental HQoL. This might suggest that emotional loneliness is a predictor of higher PR success. However, future studies are certainly needed to further explore this assumption.
Notably, with 48% percent we observed a high prevalence of moderate-to-very severe loneliness in COPD patients, especially when compared with the general age-matched population where loneliness ranges from 8 to 10% (Citation52). This is in line with Kara et al. (Citation17), who observed moderately high loneliness in 60% of COPD patients of their sample. The specific reasons for these high levels of loneliness remain unknown from the present study and require future investigation. However, it can be speculated that physical and pulmonary restrictions lead to fewer social contacts, loss of a normal social life (Citation9), and cause some patients to be homebound or even chair bound (Citation10,Citation11). This can contribute to feelings of social exclusion and loneliness (Citation9,Citation12–14). Furthermore, due to episodic fluctuations in disease and exacerbation status, there may be a wide variability in the social support needed at different moments by COPD patients, which requires a flexible attitude of their social network. This may sometimes lead to mutual misunderstandings and frictions between patients and their social network concerning momentary patient needs. In such cases, patients may not attain their desired quality in social relations and may experience more feelings of loneliness (Citation53).
Moreover, we observed the strongest associations between PR outcomes and emotional loneliness, but only a sporadic association with social loneliness. This suggests that perceived social loneliness may not be as predictive as emotional loneliness for PR outcomes in patients with COPD. Similar findings have been observed by Lyyra and Heikkinen (Citation29) in older adults and by Drageset et al. (Citation30) in patients with cancer. Drageset et al. (Citation30) suggested that because of their progressive physical limitations patients are unable to uphold social contacts and thereby seem to give priority to emotional support instead of maintaining a larger network. Together, these results are in line with previous theories that social and emotional loneliness are different types of loneliness (Citation28), and that clinical treatments should focus on the latter.
When interpreting the present results, some limitations of the study should be kept in mind. First, the single-center setting and the specific nature of the PR program (i.e. in-patient) reduce the generalizability of our findings. It can also not be excluded that a specific subgroup of socially isolated patients is referred to these types of programs. Conclusions about the impact of loneliness on other forms of treatment, e.g. less intensive but longer outpatient PR programs and primary care settings, require future investigations. Second, as our prospective analysis of loneliness and PR outcomes covered only 3 weeks, future studies should include longer follow-up periods. Notably, levels of loneliness might change again once patients return to their normal home situation. Finally, our study included 6MWD as a measure of functional capacity. Although moderately correlated, 6MWD cannot be used to reliably identify patient’s physical activity, especially in patients with sedentary lifestyles. Therefore, future studies should include more ecologically valid measurements of physical activity such as accelerometer-based activity monitors.
Conclusions
In summary, the present study demonstrated that loneliness was highly prevalent amongst an inpatient cohort of COPD patients enrolled in a PR program. Importantly, emotional loneliness was associated with worse outcomes of inpatient PR including reduced functional capacity and HQoL, and increased levels of depression and anxiety cross-sectionally, but with better outcomes prospectively. Stronger decreases in emotional loneliness were associated with better outcomes prospectively. These results suggest that the detection and treatment of emotional loneliness in patients with COPD might be clinically important. Future studies are needed to further investigate the role of loneliness in the long-term disease progression of COPD and how it might impact other forms of treatment.
Author contributions
Conception and design (TR, MS, DJ, KS, AvL); data acquisition (MS, DJ, KS); data analysis (TR, AvL); interpretation of data (TR, MS, DJ, TT, WJ, KS, AvL); drafting the manuscript (TR, MS, DJ, TT, WJ, KS, AvL); manuscript revision (TR, MS, DJ, TT, WJ, KS, AvL).
Guarantor statement
TR and AvL had full access to all of the data in the study and take full responsibility for the integrity of the data and accuracy of the data analysis.
Other contributions
The authors wish to thank Sibylle Petersen, Eva Elisabeth Münch, and Berta Obermaier for their assistance during the data collection.
Disclosure statement
No potential conflict of interest was reported by the authors.
Additional information
Funding
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