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(Chest. 2003;123:136-141.)
© 2003 American College of Chest Physicians

Evaluation of Health-Related Quality of Life in Low-Income Patients With COPD Receiving Long-term Oxygen Therapy*

Cláudia Adriana Sant’Anna, Ferreira, PT; Rafael Stelmach, MD; Maria Ignez Zanetti Feltrin, PT; Wilson Jacob Filho, MD; Toshio Chiba, MD and Alberto Cukier, MD, FCCP

* From the Division of Respiratory Diseases, Heart Institute (InCor)/Hospital das Clínicas and the Division of General Internal Medicine, University of Sao Paulo School of Medicine, Brazil.

Correspondence to: Alberto Cukier, MD, FCCP, Al. Jau, 263 apto 101, 01420-000, Sao Paulo, Brazil; e-mail: pnealberto{at}incor.usp.br


   Abstract
TOP
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Study objective: To assess health-related quality of life (HRQL) in a low-income population of patients with hypoxemia and COPD receiving long-term oxygen therapy (LTOT).

Design: Cross-sectional study.

Setting: Large, tertiary care, university teaching hospital.

Patients or participants: Thirty-six patients with COPD requiring LTOT (mean age, 63.5 years; mean FEV1, 32.1% of predicted; PaO2, 50.2 mm Hg) and 33 control subjects with COPD but no severe hypoxemia (mean age, 63.1 years; FEV1, 35.7%; PaO2, 66.5 mm Hg).

Interventions: Patients underwent pulmonary function testing to assess physiologic function and the degree of respiratory impairment. A baseline dyspnea index (BDI) was used to determine levels of dyspnea, and a 6-min walk test was performed to evaluate physical performance and exercise capacity. The St. George Respiratory Questionnaire (SGRQ) and the Medical Outcomes Study Short-Form 36-item questionnaire (SF-36) were used to assess health status and HRQL.

Measurements and results: The scores on the SGRQ and SF-36 indicated severe impairment. Patients receiving LTOT showed a trend toward worse scores on most dimensions of the SGRQ and SF-36, but differences between groups were only statistically significant for the physical functioning and social functioning dimensions of the SF-36. Dyspnea, as measured by the BDI, significantly correlated with all questionnaire domains except the SF-36 pain index.

Conclusions: The HRQL of these low-income patients with COPD was markedly impaired, with more pronounced impairment in those receiving LTOT. The severity of dyspnea was a significant predictor of various components of quality of life in these patients.

Key Words: COPD • long-term oxygen therapy • quality of life


   Introduction
TOP
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
Treatment of COPD is largely palliative, directed toward symptom control and the reduction of acute exacerbations. The impact of the disease and its treatment on the health-related quality of life (HRQL) of these patients has been studied in recent years. Compared with the general population, patients with severe COPD have significant impairment in their quality of life (QoL).1 2 3 4 5 QoL is lower in patients with severe COPD, but even those with mild disease have HRQL levels lower than those seen in the general population.2 This impairment manifests not only as a loss of physical mobility, but also as emotional and sleep disturbances.6

Long-term oxygen therapy (LTOT) became a standard treatment for patients with COPD and severe hypoxemia, mainly due to reports of increased life expectancy in such patients.7 8 9 Several studies have shown the deterioration in the QoL of patients with COPD and hypoxemia.3 4 10 11 However, few studies have addressed the impact of LTOT on QoL, and available results are conflicting. Okubadejo et al12 detected no change in the QoL of patients with COPD after 6 months of LTOT. Other investigators have reported similar results.13 14 Conversely, there are some reports of improved QoL after LTOT.7 15

The aim of this study was to use the Portuguese (Brazil) version of the St. George Respiratory Questionnaire (SGRQ) and the Medical Outcomes Study Short-Form 36-item questionnaire (SF-36) to evaluate HRQL in a low-income population of patients with hypoxemia and COPD receiving LTOT. These results were compared with those from patients with a similar degree of airflow limitation but less severe hypoxemia not requiring LTOT, who served as a control group.


   Materials and Methods
TOP
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
Setting
This study was conducted in a large, tertiary care, university teaching hospital in Sao Paulo, Brazil. The patients assisted at our institution belong to the least-favored segment of the population. The average monthly family income of the patients receiving LTOT was approximately $350. None of the patients included in this study would have been able to afford LTOT.

Patient Population
Study subjects included patients with COPD and severe hypoxemia from an outpatient chest clinic at our institution, who had been receiving LTOT from cylinders for 2.5 ± 2.0 years (mean ± SD) [LTOT group]. All patients in the LTOT group had a diagnosis of COPD, a FEV1 < 1.5 L, and a PaO2 < 55 mm Hg when stable, or a PaO2 < 60 mm Hg with evidence of cor pulmonale or polycythemia. Exclusion criteria were radiologic evidence of any significant abnormality not attributable to COPD, an inability to understand or complete QoL questionnaires, and an inability to perform the 6-min walking test.

Of 91 adult patients receiving LTOT, 48 patients had a diagnosis of COPD. Of these, seven patients died during the recruitment period, three patients were hospitalized, and two patients were excluded from the study due to low adherence to the LTOT regimen (assessed by cylinder refill). The remaining 36 patients with COPD receiving LTOT were enrolled in the study (LTOT group). Their mean age was 63.5 ± 10.8 years, and 21 patients were male. Thirty-three patients (25 men) with COPD but less severe hypoxemia comprised the control group. The mean age of the control subjects was 63.1 ± 9.2 years, and none of these patients were receiving LTOT.

Assessment Procedures
Parameters assessed included physiologic function and functional respiratory impairment (spirometry, arterial blood gas analysis), level of dyspnea (baseline dyspnea index [BDI]), physical performance (6-min walking distance), and HRQL (QoL questionnaires). The validated Portuguese (Brazilian) versions of the SGRQ16 and the SF-3617 were used to measure QoL. All assessments in both groups were made by the same person who administered the questionnaires because some of the patients were illiterate.

The disease-specific SGRQ contains 76 items that produce three component scores related to symptoms, activity, and impact, as well as a total score. The symptoms score reflects the frequency and severity of respiratory manifestations, the activity score relates to activities that cause or are limited by breathlessness, and the impact score reflects aspects of social functioning and psychosocial disturbances that result from respiratory diseases. Scores on the SGRQ range from 0 (no disturbance of HRQL) to 100. The SF-36 is a general questionnaire that measures HRQL across eight domains: physical functioning, role physical, role emotional (role limitations due to emotional problems), social functioning, general health perceptions, mental health, bodily pain, and vitality. Higher scores on the SF-36 (range 0 to 100) indicate better QoL.

Spirometry measurements were obtained with the patient in a clinically stable condition. Results of blood gas analysis performed for diagnostic or therapeutic purposes up to 6 months before study enrollment were obtained from patient medical records. The maximum inspiratory pressure (PImax) and maximum expiratory pressure (PEmax) were determined from the functional residual capacity. Dyspnea was assessed using the BDI,18 and the exercise capacity was evaluated by a 6-min walking test conducted in a 25-m hospital corridor. Patients with an oxygen saturation of < 90% at rest received supplemental oxygen. The Ethics Committee at our institution approved the study, and all patients provided written informed consent to participate.

Statistical Analysis
All data are expressed as means (SD). The Student t test19 was used to compare measures of physiologic function, dyspnea, and physical performance between groups, whereas the Wilcoxon rank sum test19 was considered more suitable for comparing QoL variables. Pearson correlations19 were used to assess the strength of linear relationships between variables. Results were considered statistically significant at p < 0.05.


   Results
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
Sixty-nine patients with COPD completed the study. Table 1 summarizes measures of physiologic function, dyspnea, and physical performance (exercise capacity). The groups were matched according to flow limitation, as measured by FEV1. Compared to the control group, the LTOT group had a lower FVC (p = 0.001), more severe hypoxemia (p = 0.001), and hypercapnia (p = 0.001). The LTOT patients also had significantly worse dyspnea and exercise capacity scores. The PImax was similar in both groups, but the LTOT group had a significantly lower PEmax.


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  		Table 1. Measures of Physiologic Function, Dyspnea, and Physical Performance*

 
Tables 2 , 3 list the mean scores for the SF-36 and SGRQ in both groups. Overall, patients receiving LTOT seemed to have a worse HRQL, but the differences between groups were only statistically significant for two of the SF-36 dimensions, physical functioning and social functioning. Table 4 shows correlations between the component scores on the SF-36 and SGRQ and physiologic variables, dyspnea ratings, and exercise capacity. Dyspnea, as measured by the BDI, significantly correlated with all domains except the SF-36 pain index.


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  		Table 2. SF-36 Scores*

 

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  		Table 3. SGRQ Scores*

 

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  		Table 4. Correlations Between HRQL Component Scores and Measures of Physiologic Function, Dyspnea, and Physical Performance in 69 Patients

 

   Discussion
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
Our results indicate that patients with moderate-to-severe COPD have a marked impairment in HRQL. Patients receiving LTOT appeared to have worse scores on almost all dimensions of the SF-36 and SGRQ questionnaires, although differences were statistically significant only for physical functioning and social functioning dimensions of the SF-36.

There are no prior reports about the performance of the Portuguese version of the SGRQ and little data regarding the Portuguese version of the SF-3620 since these questionnaires were validated in Brazil. Therefore, it is important to compare our results from these questionnaires with previously published data. Several authors have examined the profile of the effect of COPD on the SGRQ.2 12 21 22 23 24 In a Spanish cohort, Ferrer et al2 showed that the effect of COPD on QoL increased as disease severity increased. Mean SGRQ total scores for patients with American Thoracic Society25 stage I, II, and III disease were 34, 42, and 55, respectively. On all sections of the SGRQ, scores were moderately to strongly associated with FEV1 categories. Dyspnea also increased in a statistically significant manner as FEV1 worsened. In contrast, Hajiro et al23 did not find a relationship between American Thoracic Society disease stage and SGRQ scores, because of a lack of difference between scores of patients with stage II and III disease. However, the same group24 recently reported a relationship between disease stage based on British Thoracic Society guidelines and SGRQ scores. In both studies, a significant association was detected between the level of dyspnea and SGRQ scores. Ketelaars et al26 reported the results of 126 Dutch patients with COPD (mean age, 65 years; mean percentage of predicted FEV1, 39%) whose mean SGRQ component scores were 64 for symptoms, 68 for activity, and 46 for impact. Significant correlations were found between the FEV1, performance on the 12-min walking test, coping strategies, and the HRQL components of activity and impact.

Few studies have evaluated COPD patients with the SF-36 questionnaire.23 27 28 Crockett et al28 compared the results of the Nottingham Health Profile and the SF-36 questionnaires obtained at baseline in 60 Australian patients with severe COPD being assessed for LTOT. They showed serious impairment in the QoL of these patients due to large decrements in physical health and smaller decrements in emotional and mental health. Mahler and Mackowiak27 administered the SF-36 questionnaire to 50 patients with COPD (mean FEV1, 48% predicted) and showed that dyspnea ratings were significant predictors of seven of the components of the SF-36. The same tendency was recognized in the study by Hajiro et al,23 the sole previous study to have used both the SGRQ and SF-36 to assess COPD patients. Hajiro and colleagues23 found that scores on all scales of the SF-36 except for mental health and bodily pain were significantly lower in patients with moderate-to-severe dyspnea than in patients with mild dyspnea. The importance of dyspnea as the major limiting factor of COPD was confirmed by our documentation of a relationship between BDI scores and scores on all domains of the SGRQ and seven components of the SF-36.

Studies that have used different assessment tools have produced similar results.1 3 4 Overall, these studies suggest that while the functional status and health perceptions of patients with COPD may not be related solely to observable pulmonary impairment, their HRQL appears to be related to the degree of pulmonary disease. Moreover, most results emphasize the importance that patients place on dyspnea, the leading symptom of this disease. Our results in moderately to severely impaired patients are in accordance with these data. Our patients’ mean scores on individual SGRQ and SF-36 components were comparable to those reported for similarly compromised patients2 12 21 22 26 28 and worse than those obtained in patients with milder disease.2 27 The only exceptions applied to comparisons with scores obtained in two Japanese studies.23 24 Hajiro and colleagues23 reported better scores for both the SGRQ and SF-36 in their COPD patients, suggesting some cultural differences in responding to the questions between Oriental and occidental populations.

The influence of hypoxemia and LTOT on the QoL of patients with COPD has been addressed in several reports. In the Nocturnal Oxygen Therapy Trial, hypoxemic patients demonstrated significant impairment in most domains of a generic questionnaire compared to a control group. A relationship was found between neuropsychological impairment and QoL scores. However, no relationship was found between PaO2 and QoL scores,4 11 in contrast to findings in other studies.2 21 29 30 31

Okubadejo et al12 21 22 reported different aspects related to hypoxemic patients with COPD in three sequential articles. In their first study,21 they used both general and disease-specific questionnaires to investigate the relationship between blood gas data and QoL in a group of 41 patients with severe COPD and a mean PaO2 of 56 mm Hg. They observed a relationship between hypoxemia and SGRQ scores, in that the PaO2 was associated with higher, thus, worse QoL scores. The SGRQ symptoms and impact scores correlated with levels of hypoxemia, but the activity score did not. In the second study, Okubadejo et al12 evaluated a group of patients who were selected to start LTOT and another group of COPD patients with less severe hypoxemia. All patients were followed up for 6 months. Compared with the control group, patients receiving LTOT had a nonsignificant improvement in their QoL. The investigators concluded that LTOT does not have a major beneficial effect on QoL, but that it also does not reduce health status. The aim of their third study22 was to assess relationships between activities of daily living (ADL), QoL, mood state, and airway obstruction in patients with severe hypoxemic COPD using LTOT and in patients with severe COPD who did not meet the criteria for LTOT. This study showed that independence in ADL is related to the degree of airflow limitation, health status, and mood. The patients using LTOT were significantly less independent in their ADL than the control group.

Our patients using LTOT had worse scores on almost all dimensions of the SF-36 and SGRQ questionnaires, although differences were statistically significant only for physical functioning and social functioning dimensions of the SF-36. We observed weak relationships between a few HRQL domains and FEV1 or PaO2. Compared to the control group (matched in terms of FEV1), the hypoxemic patients were more disabled and symptomatic, as suggested by worse BDI scores and shorter distances achieved on the 6-min walking test.

A possible implication of these results is that LTOT does not improve dyspnea. However, we are unable to draw such a conclusion due to the cross-sectional design of this study. Previously published studies have addressed the influence of the administration of oxygen on the perception of dyspnea, with conflicting results. Besides reports suggesting that hypoxemic and breathless patients benefit symptomatically from supplemental oxygen,32 33 there are other studies that have not confirmed such an effect.34 35 Still other authors have concluded that oxygen prescribed for symptomatic relief of dyspnea may benefit only select patients with COPD.36 37

We matched the groups in our study according to flow limitation, as measured by the FEV1. However, compared to the control group, the LTOT group had a significantly lower FVC. One possible explanation for this finding is that a concomitant restrictive lung disease might have been present in the LTOT group. Although a definitive conclusion is not possible, as we did not measure lung volumes, this possibility seems unlikely based on clinical and radiologic data. A more probable explanation, which could also explain the significantly worse dyspnea and exercise capacity scores, is that the lungs of the LTOT patients were hyperinflated.

LTOT also can influence emotional states, which are determinants of QoL. As we did not use specific measures of neuropsychological impairment, we cannot address how our low-income population coped with the situation. Published data suggest that patients tend not to accept oxygen therapy for several reasons, including the restricted mobility and noise disturbance imposed by the oxygen delivery equipment,10 the negative expectation linked to the use of a device for extended periods to maintain health,22 and leisure or work limitations as patients become housebound or nearly housebound.10 11 22

In conclusion, patients with COPD have important HRQL impairment that is multifactorial in origin. As the disease progresses, the limitation worsens and very few interventions influence this evolution. After hospitalization, oxygen therapy represents the largest share of the total direct medical cost of respiratory care for patients with COPD receiving LTOT.38 In Brazil, LTOT is mainly carried out by institutions reimbursed by the government, at a monthly cost per patient of approximately $150. The worldwide debate over the cost-benefit and affordability of LTOT38 39 is even more pertinent in economic emergent countries. Cost-benefit analysis needs to establish which interventions optimize the health of the system as a whole, so that the scarce resources devoted to health care may be optimally distributed. Although the best methods for judging the economic value of health-care interventions are controversial,40 determining the influence of any intervention via measures which go beyond clinical and mortality end points will be increasingly mandatory. Studies comparing LTOT patients with various incomes and in different settings could help clarify this issue.


   Acknowledgements
 
The authors thank Carine Favalli Redigolo for performing statistical analysis.


   Footnotes
 
Abbreviations: ADL = activities of daily living; BDI = baseline dyspnea index; HRQL = health-related quality of life; LTOT = long-term oxygen therapy; PEmax = maximum expiratory pressure; PImax = maximum inspiratory pressure; QoL = quality of life; SF-36 = Medical Outcomes Study Short-Form 36-item questionnaire; SGRQ = St. George Respiratory Questionnaire

Received for publication January 2, 2002. Accepted for publication July 16, 2002.


   References
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

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