Quality of life of idiopathic pulmonary fibrosis patients

Idiopathic pulmonary fibrosis (IPF) or cryptogenic fibrosing alveolitis is a common interstitial lung disease of unknown aetiology. However, the clinical entity is well-defined. IPF is defined as “a specific form of chronic fibrosing interstitial pneumonia limited to the lung and associated with the histologic appearance of usual interstitial pneumonia (UIP) on surgical obtained lung biopsy” 1. Most importantly, the diagnosis of IPF is made by exclusion of all known causes of fibrosing alveolitis 1, 2.

The patient demonstrates breathlessness, nonproductive cough and bibasilar and inspiratory dry rates, and there are findings of finger clubbing. Constitutional symptoms such as weight loss, malaise, and fatigue may be present. Shortness of breath is usually the most salient and disabling symptom and is usually present at least 6 months before presentation 1.

The age at onset varies from 40–70 yrs. The clinical course is highly variable. However, in general, the prognosis is poor 1, 3–5. The median survival after diagnosis is <5 yrs 1, 2, 5. IPF is a potentially fatal disorder without spontaneous remission. Therefore, the majority of the patients require therapy. Subjective improvement occurs frequently. However, objective improvement in the decrease of symptoms, radiographic clearing, or physiological improvement, assessed by lung functions tests, occurs in <25% of treated patients 1, 2, 5, 6.

IPF patients have a limited life expectancy. In cancer patients, much is known about the impact of a short life expectancy. In a previous study 7, some IPF patients were shocked by the condition of other more severe IPF patients. This seems to indicate that patients are not fully aware that they have a fair chance of dying within a few years.

Regarding the quality of life (QOL) of IPF patients, little is known 1, 7. Recently, a study among IPF patients with the aim of identifying the aspects of QOL that are relevant to this population was conducted. Results indicated that hobbies/leisure activities, mobility, transport, social relationships, working capacity, energy, and doing things slower were aspects relevant to IPF patients' QOL 7.

The severity of IPF, the poor prognosis and, in general, disappointing response to therapy resulting in a reduced life expectancy, emphasize the importance of this issue. Therefore, the aims of this study were to assess the QOL and depressive symptoms in IPF patients, the relationship between the QOL factors “fatigue” and “negative feelings”. The study also aims to identify factors that are related to QOL (perceived illness severity, illness duration), and to identify impaired aspects of QOL to guide future rehabilitation programmes. Based on a previous study 7, QOL measurement was expanded with additional social support questions. Shortness of breath is a prominent feature of IPF and it can have a major impact on patients' QOL 8. Therefore, breathlessness was also measured with the aim of examining the relationship between QOL and objective (clinical data) as well as subjective breathlessness, and establishing the influence of (objective and subjective) breathlessness on overall QOL.

Material and methods

Results

The demographic (also healthy group), medical and psychological characteristics, as well as complaints of the IPF group are summarized in table 1⇑. The comparison of QOL scores between the IPF group and the control group are shown in table 2⇓. It appeared that the QOL of the IPF group was impaired with regard to their general QOL and the domains “physical health” and “level of independence”. At facet level, IPF patients had problems with “pain and discomfort”, “energy and fatigue”, “sleep and rest”, “activities of daily living”, “dependence on medication or treatments”, “working capacity”, “ability to acquire new information and skills”, and “participating in, and possibilities for recreation/leisure”. The QOL of IPF patients using oxygen did not differ from IPF patients who did not use oxygen. Steroid use was unrelated to dyspnoea and QOL.

Patients' FEV₁ appeared to be related to the domains “psychological health”, “social relationships”, and “environment”. Furthermore, FEV₁ was significantly correlated with “overall QOL”, “pain and discomfort”, “positive feelings”, “self-esteem”, “negative feelings”, and “participating in, and possibilities for recreation/leisure” (table 3⇓). Arterial oxygen saturation (S_a,O2) decrease on exertion was related to the QOL domain “level of independence” and the facet “transport and P_a,O2 at rest” was positively correlated with patients' “overall QOL”. The T_L,CO was not associated with any QOL aspect (table 3⇓). No relationship was found between subjective breathlessness and the question on perceived seriousness of illness, on the one hand, and lung function parameters or illness duration, on the other hand. With regard to the social support questionnaire, emotional support was negatively related to FEV₁, whereas “understanding” and the total social support score were negatively related to S_a,O2 decrease on exertion. Illness duration was associated with “ability to acquire new information and skills” (table 3⇓).

Perceived seriousness of illness was related to the QOL domains “physical health” (r=−0.47; p<0.05) and “level of independence” (r=−0.44; p<0.05) and the QOL facets “pain and discomfort” (r=0.49; p<0.05), “energy and fatigue” (r=−0.64; p<0.005), “dependence on medication or treatments” (r=−0.50; p<0.05), “working capacity” (r=−0.57; p<0.01), and “sexual activity” (r=0.66; p<0.005). Seriousness of illness appeared to be unrelated to depressive mood (BDI/CDI).

The number of patients with a BDI score of ≥15 was eight (23.5%; n=34), whereas nine patients (26.5%; n=34) had a CDI score of ≥9. Both BDI and CDI scores correlated highly with the WHOQOL-100 facet score “negative feelings” (r=0.73 and r=0.75; p<0.001, respectively). The correlations between the BDI and CDI scores, and the WHOQOL-100 “energy and fatigue” facet scores were not significant. The BDI was related to the breathlessness scale “affective/emotional” (r=0.55; p<0.01) whereas the CDI was correlated with the breathlessness scales “affective/emotional” (r=0.53; p<0.01) and “low energy” (r=0.44; p<0.05).

The correlations between subjective breathlessness and QOL are presented in table 4⇓. As can be seen, shortness of breath is related to most domains and facets of patients' QOL. Exceptions are the QOL facets “sleep and rest”, “mobility”, “dependence on medication”, “health and social care”, “ability to acquire new information and skills”, and “transport” as well as the domain “spirituality/religion/personal beliefs” which showed no significant correlation with any of the BBS scales or the total BBS score.

Subsequently, a stepwise multiple regression analysis was performed to examine the relationship between breathlessness and QOL further. A conservative strategy was adopted in which the demographic variables age and sex were entered as a block in the first step of the regression analysis and the pulmonary function parameters (FEV₁, T_L,CO, and P_a,O2 difference score) as a block in the second step of the analysis to statistically adjust for their influence, despite negligible associations with overall QOL and breathlessness. In the final model with overall QOL as dependent variable (R²=0.98; F(6,2)=20.8, p<0.05), sex (β=−0.74; t=−5.3, p<0.05) and effective/emotional descriptions of breathlessness (β=−1.16; t=−7.3; p<0.05) were the only factors that significantly contributed to the prediction of overall QOL.

Age and sex were not associated with depression (BDI and CDI), negative feelings, duration of illness, FEV₁, T_L,CO, and S_a,O2 decrease on exertion. Age was related to both perceived seriousness of illness (r=−0.44; p<0.05; n=21) and the BBS scale “physical sensations” (r=−0.38; p<0.05), whereas sex was not.

Discussion

The QOL of the IPF patients was mainly impaired in the domains “physical health” and “level of independence” compared with a matched healthy control group. In general, these results are similar to those found in another common interstitial lung disease, i.e. sarcoidosis 13.

In contrast to previous findings in sarcoidosis 13, the FEV₁ appeared to be related to QOL. Especially, “psychological health” (domain level), “social relationships” (domain level), “environment” (domain level), “overall QOL”, “pain”, “positive feelings”, “negative feelings”, “self-esteem”, and “recreation/leisure” appeared to be related to the FEV₁. When comparing the aspects of QOL associated with FEV₁, with the facets in which the QOL of IPF patients is impaired, it appears that the results are only congruent for “overall QOL”, “pain”, “self-esteem”, and “recreation/leisure”. It is striking that the QOL domains impaired in IPF patients are not associated with FEV₁. Moreover, the other lung function parameters were hardly related to patients' QOL. An exception was S_a,O2 decrease during exertion, which was related to the QOL domain “level of independence” and the facet “transport”. Although caution in the interpretation is warranted, as the sample size of the studied patient population was rather small, it is reasonable to assume that although FEV₁ was related to QOL, lung function parameters, except S_a,O2 decrease during exertion, are not reliable indicators of QOL impairment in IPF patients.

Subjective dyspnoea, especially the effective/evaluative and low energy scales, appeared to be correlated with many domains and various aspects of QOL. However, subjective dyspnoea was not related to the pulmonary function parameters which are measures of lung capacity and thus, indirectly, objective dyspnoea measures. Patients' perception of dyspnoea is not associated with objective breathlessness measures. The regression analysis showed that the male IPF patients and patients with a low score on effective/emotional breathlessness indicated a better overall QOL.

The major QOL problems of the IPF patients appeared to be fatigue, mobility, activities of daily living, and working capacity. As mentioned above, none of these QOL aspects was significantly related to the lung function parameters. Although abnormal physical exhaustion and fatigue are often regarded as a natural consequence of pulmonary diseases, in linewith the present observations, Gugger 21 assumed that, apart from factors specifically related to pulmonary diseases, psychosocial factors are mainly responsible for the impaired physical fitness and fatigue. Therefore, it was recommended that a careful evaluation of psychological aspects be included in the diagnostic evaluation of patients suffering from a certain pulmonary disorder 21. Moreover, the assessment, support, and reinforcement of a patient's psychosocial assets and ability to cope with chronic respiratory difficulty can help enhance the QOL, and decrease feelings of fear for the manifestations and/or treatments of disease 22–24.

The patients' perception regarding the severity of their illness was not related to objective measures of severity and illness duration. This indicates that the patients' own opinions about the severity of their disease is not in accordance with objective data. This is in alignment with the fact that patients frequently report subjective improvement despite no objective improvement 1, 2, 5, 6. Possible explanations are that: 1) patients suppress information concerning the seriousness of their disease; 2) patients have psychologically adapted to their situation; and/or: 3) patients feel thattheir situation is better than indicated by their physicians. Which of these reasons play a key role, needs to be explored.

Perceiving IPF as a severe disease is related to impaired physical health, as well as reduced feelings of independence from others. More specifically, disease severity is associated with more pain, more fatigue, an impaired working capacity and more dependency on medication. Thus, the perceived seriousness of IPF has a negative influence on patients' QOL. Surprisingly, perceiving IPF as a severe illness was related to more sexual activity. Presumably, patients want to enjoy life as much as possible and, therefore, take advantage of their sexual activity, in one of its many forms, as long as possible. Studies among populations of rheumatoid arthritis, psoriasis, and sarcoidosis patients 25, 26 revealed no sexual difficulties.

Remarkably, the perceived seriousness of IPF, as well as fatigue scores, were not related to depressed mood. In a study among sarcoidosis patients, a relationship was found between fatigue and depression scores 13. The authors realize that the sample size was rather small. Therefore, these results should be interpreted with care. A larger study is needed in order to replicate the results from the present study. However, considering the high correlation between the BDI and the WHOQOL-100 facet “negative feelings”, using a separate measure for assessing depressive mood seems to be redundant. Further studies exploring this issue are required.

In the present study, 23.5% of the patients who fully completed the BDI had a score indicative of significant depressive symptoms. Using the CDI score, which excludes physical symptoms of depression, comparable results emerged. In another study, IPF patients who participated in focus groups spontaneously mentioned feelings of depression 7. It emerges that more attention should be paid to the negative feelings of IPF patients. The fact that general fatigue (measured with the WHOQOL), a symptom of clinical depression, was unrelated to the BDI/CDI scores implies that although IPF patients are bothered by negative feelings, they are in general, not clinically depressed. The relationship between the CDI and the breathlessness scale “low energy” (physical fatigue) might indicate that dyspnoea causes fatigue. Previously, it appeared, that in a group of sarcoidosis patients 13, the presence of symptoms played a major role regarding those feelings. Moreover, sarcoidosis patients with complaints demonstrated higher BDI scores compared to patients without complaints 27.

Most of the aspects of impaired QOL in IPF are notmeasured by disease-specific health status (or nowadays also called health-related QOL) lung questionnairessuch as the St. George's Respiratory Questionnaire (SGRQ). QOL has a much wider scope than the physical, emotional, and social domains usually studied in health status measures. Health status measures assess fewer aspects and, therefore, provide less specific information concerning patients' problems. Moreover, aspects such as fatigue are not usually assessed in health status measures. Furthermore, QOL instruments measure a person's own evaluation of their functioning, whereas health status measures assess patients' physical, emotional and social functioning 7, 28. The reliability and validity of the WHOQOL-100 are high 14. Within a group of sarcoidosis patients the WHOQOL-100 distinguishes well between patients with and without complaints 13, 15. Previously, it was established that the WHOQOL-100 was preferable to the SGRQ in IPF 7. Reasons were, for instance, that focus group participants made substantial negative remarks about the SGRQ, the scales of this questionnaire were not mentioned as important aspects of life and the SGRQ only measures three aspects (symptoms, activity, and impact). This provides very limited information with regard to problems that patients may experience 7. In line with this, results from the present study indicate that the WHOQOL-100 appeared to be useful in IPF. In contrast, Chang et al. 29 studied a group of interstitial lung disease patients (33 IPF, 10 sarcoidosis, seven miscellaneous) and concluded that the Short Form 36 Item Questionnaire (SF-36) and SGRQ are good tools for measuring health-related QOL or health status. The discrepancy between their findings and other previous findings 7 might be caused by the fact that focus groups were used in other studies, in which IPF patients themselves could comment on the measures and did not rely solely on psychometrics. The SF-36 might be a good measure for assessing health status in IPF. The choice between a health status measure and a QOL measure should be based on the aim of a study 28. If the interest is only in functioning, then the SF-36 might be suitable 29, 30. However, if the interest is in the opinion of the patients, then the WHOQOL-100 is a suitable measure. Before using the SF-36, the usefulness and acceptability of the instrument should be studied from the patients' view pointwith, for example, focus groups or individual interviews.

Although the severity, disablement and shortened life expectancy of IPF might be comparable with another serious illness such as cancer, less attention has been paid to these issues and until now hardly any rehabilitation programmes have been prepared for patients suffering from IPF. This study intended to focus on the aspects of QOL impairment of IPF patients. Rehabilitation programmes should be developed to improve the knowledge of patients and their families about the severity of the disease and to improve adaptive coping with the disease. In a study among chronic leukaemia patients, coping reflected the different strategies adopted to manage patients' capacity for getting through difficult times. The adaptive strategy action included acquiring as much information as possible about their disease 31.

In conclusion, the quality of life of idiopathic pulmonary fibrosis patients was mainly impaired in the areas “physical health” and “level of independence”. Perceived seriousness of idiopathic pulmonary fibrosis was related to the same quality of life domains. The World Health Organization Quality of Life assessment instrument-100 facet “negative feelings” appeared to beuseful to assess depressive mood. Fatigue was unrelated to the depressive mood. Furthermore, although quality of life aspects were related to lung function impairment, it only concerned nonimpaired aspects. Subjective breathlessness was associated with depressive mood and quality of life. Finally, sex and the effective/emotional breathlessness scale were the only predictors of overall quality of life. Therefore, it is reasonable to assume that the assessment, support and reinforcement of a patient's psychosocial assets and ability to cope with idiopathic pulmonary fibrosis can help enhance the quality of life. Moreover, these aspects should be a primary consideration in the development of rehabilitation programmes for patients suffering from idiopathic pulmonary fibrosis as well as pathophysiological aspects of this severe pulmonary disorder.