Quality of Life After Pulmonary Rehabilitation: Assessing Change Using Quantitative and Qualitative Methods.

Background and Purpose. The purpose of this study was to use quantitative and qualitative research methods to evaluate quality-of-life (QOL) changes in patients with chronic obstructive pulmonary disease (COPD) after pulmonary rehabilitation. Subjects. Twenty-nine individuals with COPD (18 women and 11 men), with a mean age of 69 years (SD=8.6, range=53-92), participated. Methods. Subjects were assessed before and after a 5-week control phase and after a 5-week rehabilitation phase using the Chronic Respiratory Questionnaire (CRQ), the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36), and spirometry. Our qualitative research was based on a subsample of 7 subjects who were interviewed after pulmonary rehabilitation. Results. Pulmonary rehabilitation improved QOL, as demonstrated by increases of 22% and 14% in the physical function categories of the CRQ and the SF-36, respectively, and by an increase of 10% in the CRQ's emotional function category. The qualitative data indicated how pulmonary rehabilitation influenced QOL. Conclusion and Discussion. The use of both quantitative and qualitative methods illustrated the nature of improvement in QOL after pulmonary rehabilitation. Improved physical function, less dyspnea, and a heightened sense of control over the subjects' COPD resulted in increased confidence and improved emotional well-being. [Camp PG, Appleton J, Reid WD. Quality of life after pulmonary rehabilitation: assessing change using quantitative and qualitative methods. Phys Ther. 2000;80: 986-995.]

Key Words: Chronic obstructive pulmonary disease, Pulmonary rehabilitation, Quality of life.

Chronic obstructive pulmonary disease (COPD) is a progressive, disabling pathology that can severely affect a person's quality of life (QOL). Pulmonary rehabilitation is an intervention that can combine exercise, education, and behavior modification strategies in an effort to minimize symptoms and improve QOL. Previously, pulmonary rehabilitation has been evaluated using mainly physiologic quantitative measures, such as exercise tolerance,[1-3] oxygen consumption,[1,4] and workload performance.[1,5] More recently, evaluation of rehabilitation has been expanded to include measures of personal experiences, such as through the use of dyspnea scales,[1,5,6] and standardized QOL questionnaires.[1-3] Two review articles,[7,8] including one based on the views of a panel of experts examining levels of evidence, have documented the benefits of pulmonary rehabilitation. Pulmonary rehabilitation programs consisting of exercise and education similar to that utilized in this study have been shown to improve exercise tolerance[2,8] decrease dyspnea,[6] and enhance QOL[3] in individuals with COPD.[8]

The addition of QOL questionnaires in the evaluation of pulmonary rehabilitation may broaden the scope of the evaluation and perhaps provide a more comprehensive assessment of the benefits of pulmonary rehabilitation than measures of physiological change such as exercise performance or lung function. The questionnaires commonly used in pulmonary rehabilitation evaluation have been the Quality of Well-Being Scale[1] and the Chronic Respiratory Questionnaire (CRQ).[2,3] These questionnaires attempt to assess the extent of disability experienced by the individual, instead of merely the severity of impairments due to the lung disease. These questionnaires can indicate how treatment affects psychosocial, spiritual, and physical domains of a person's life rather than solely evaluating physical dysfunction such as reduced exercise tolerance. Quality-of-life questionnaires, in our view, are likely to more meaningfully reflect the benefits that a person may derive from an intervention because of the domains evaluated, rather than focusing only on measures of impairment.

Quality-of-life questionnaires have been developed and tested on large groups of individuals, including some with pulmonary disease.[9,10] Utilizing both quantitative and qualitative methods, known as mixed-methods research, to assess QOL changes after pulmonary rehabilitation may allow for characterization of individuals as well as a group of people with pulmonary disease. The purpose of this study was to determine the changes in QOL in individuals with COPD who have undergone a pulmonary rehabilitation program using both quantitative and qualitative research methods. Although quantitative assessments of QOL have been published previously, the unique feature of this study is the combination of both quantitative and qualitative methods in order to illustrate the nature of improvement in QOL.

Method

Subjects

A convenience sample of participants was recruited from the Saint Mary's Hospital Pulmonary Rehabilitation Program in New Westminster, British Columbia, Canada, and the Ridge Meadows Hospital Pulmonary Rehabilitation Program in Maple Ridge, British Columbia, Canada. Ethics approval for this study was obtained from the University of British Columbia and the participating hospitals. Subjects included in the trial were individuals with COPD (forced expiratory volume in I second [[FEV.sub.1]] [is less than] 70% of the predicted value) who were willing to participate in the 5-week control phase as well as the 5-week rehabilitation phase. In order to participate, they had to be able to read and understand the QOL questionnaires, perform the spirometric tests, and exercise. Individuals with chronic asthma or unstable pulmonary disease (defined as having a respiratory infection requiring antibiotics within 6 weeks of study admission or having a hospital admission within 3 months of study admission) were exclude from the study due to the variability in their condition. In addition, those individuals who had attended a pulmonary rehabilitation program during the 3-year period before the study, those with severe or unstable comorbid conditions, or those who contracted a respiratory infection or underwent hospitalization during the 10-week course of the study were excluded.

Forty-one participants were deemed eligible for the study and agreed to participate. Twelve of these participants dropped out for a variety of reasons, including illness and family problems. Summary characteristics of the 29 subjects who completed the program are presented in Table 1. The mean [FEV.sub.1] for the sample was 43%, which represents a sample with severe to moderately severe lung disease.[11] All participants recruited for this study were Caucasian. The attendance rate was 97%.

Table 1. Characteristics of the Study Participants (N=29)

Characteristic(a)                    [bar]X     SD      Range

Sex                         18 women, 11 men
Age (y)                                   69    8.6     53-92
[FEV.sub.1] (L)                         0.95   0.35   0.55-1.98
[FEV.sub.1] (% predicted)                 43     14     23-69
FVC (L)                                 2.18   0.75   1.34-3.84
FVC (% predicted)                         71     20     45-130
Smoking (pack-years)                      37     21      0-80

(a) [FEV.sub.1]=forced expiratory volume in 1 second, FVC=forced vital capacity.

Study Protocol

Each person participated in 3 testing sessions. There was a 5-week control phase and then a 5-week rehabilitation phase (Fig. 1). Testing included the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36),[9] the CRQ,[10] and spirometry. Tests were given in random order at each testing session. After the post-rehabilitation test, participants were asked whether they would be interested in participating in a personal interview with the researcher, conducted in the participant's home.

[Figure 1 ILLUSTRATION OMITTED]

Description of Pulmonary Rehabilitation Program

The Saint Mary's Hospital Pulmonary Rehabilitation Program has been in operation approximately 20 years. The staff have developed a 5-week program, with participants attending on a thrice-weekly basis. Each session lasts approximately 2.5 hours, with exercise and education provided at each session. The program content of the Ridge Meadows Hospital Pulmonary Rehabilitation Program is based on the Saint Mary's program.

The exercise component of each session was approximately 1.25 hours in duration. During this time, participants had a 15- to 20-minute warm-up, 30 minutes of aerobic exercise, and a 15-minute cool-down. The warm-up and cool-down phases consisted of stretching exercises for upper and lower extremities, thoracic mobility exercises, and light-resistance strengthening exercises (using elastic bands, handheld weights, or body positioning). In addition, low-intensity rhythmic movements of the upper and lower extremities, in synchrony with the individual's breathing pattern, were used to facilitate cardiovascular warm-up and cool-down.

The aerobic conditioning phase of the exercise sessions utilized several modalities. Lower-extremity ergometers, arm ergometers, combined upper- and lower-extremity ergometers, and treadmills were used. In addition, participants walked in the hall while distance and time walked were measured. Initial individual exercise prescriptions were based on pre-rehabilitation 6-minute walk test results, pre-rehabilitation dyspnea levels during exercise, comorbidities, and the participant's ability to sustain a given level of intensity for at least 5 to 10 minutes without stopping. Dyspnea levels were the primary variable used to determine exercise prescription, as long as the other variables of heart rate, oxygen saturation, and blood pressure were kept at a safe level. The participants were encouraged to exercise at intensities that allowed them to exercise for at least 10 minutes at a modified Borg Scale rating of 3 (moderate level of breathlessness) to 4 (somewhat hard breathing). Heart rate, oxygen saturation, dyspnea levels (using the modified Borg scale[12]), and exercise intensity and time were monitored for each participant on each modality, for each session. Blood pressure was monitored before and after exercise when the individual began the program. Depending on the individual's blood pressure response during exercise, the program staff would monitor blood pressure more or less frequently during subsequent sessions. Individual progression of intensity utilized the participant's rating of breathlessness. Exercise intensity was increased if the individual's modified Borg scale rating was less than 2 (easy breathing) to 3 (moderate level of breathlessness) on a particular modality. Using dyspnea targeting to guide exercise intensity is an accepted practice in pulmonary rehabilitation.[13] Exercise was monitored either by a physical therapist and a respiratory nurse or by 2 respiratory nurses. In addition, participants were encouraged to exercise at least one other session per week outside of the program, at a modified Borg Scale rating of 3 to 4, for at least 30 minutes, if possible.

The education component of the respiratory rehabilitation program was delivered by a multidisciplinary team. A respiratory nurse, a physical therapist, a respiratory therapist, an occupational therapist, a social worker, and a dietitian participated in the program and led their respective educational sessions. Sessions covered anatomy and pathophysiology of COPD, medication, identifying and avoiding lung irritants and chest infections, stress management, energy conservation, nutrition, oxygen therapy, community resources, airway clearance, exercise theory, and coping with a chronic illness. Sessions were approximately 1 hour in length, were delivered in a group format, and were discussion oriented. There were 16 participants in each education group. Not all participants in the groups were subjects. Each participant received an educational manual. The manual was a 100-page, professionally printed and bound book. Each chapter in the manual corresponded to an education topic. There were fifteen 1-hour educational sessions.

Assessment of Outcome

The 2 QOL measures used in this study were the SF-36 (acute version)[9] and the CRQ.[10] The SF-36 was completed by the participant (ie, self-administered). It has 36 items in 8 categories (Fig. 2). Questions ask individuals to rate certain aspects of their overall health, ability to perform activities of daily living, emotional status, levels of pain, and perception of their health compared with others around them. In addition to the scores for the 8 individual categories, a physical summary component score and a mental health component summary score can be calculated (Fig. 2). These scores are derived from the 8 domains and, using a z-score transformation, yield values that can be compared with norms for the general US population.[14] Ware et al[15] argued that the reduction of 8 categorical scores into 2 summary scores can be achieved without a substantial loss of information.

[Figure 2 ILLUSTRATION OMITTED]

Several studies have examined the reliability and validity of SF-36 scores. We believe that the SF-36 has met the minimum required standards for internal consistency reliability[16] and convergent and discriminant validity[17] across a variety of patient groups.[18-20] In addition, we believe that the SF-36 shows acceptable concurrent and content validity for use in individuals with COPD.

The second QOL questionnaire used in this study was the CRQ (also known as the Chronic Respiratory Disease Questionnaire).[10] The internal consistency and test-retest reliability and the content, construct, and concurrent validity of data obtained with this questionnaire have been examined[3,10,21,22] and, in our opinion, are sufficient. This interviewer-administered, disease-specific questionnaire has 20 questions covering 4 domains: dyspnea, fatigue, emotional function, and mastery (Fig. 2). The mastery domain refers to a sense of control over the disease process. Fatigue refers to tiredness or lack of energy. Each question has a 7-point Likert scale, with higher scores reflecting better physical or emotional well-being. The answers for each question related to a domain are added and then divided by the number of questions within that domain. The scores for each domain range between 1 and 7. According to Guyatt et al,[23] the developers of the questionnaire, scores from the dyspnea and fatigue domains can then be combined to form the physical function component. The emotional function and mastery domains can also be combined to make the emotional function component (Fig. 2), as outlined by Guyatt et al.[23] The physical function component or the emotional function component is derived by averaging the scores for the 2 domains that make up each component. In this way, these components are also expressed as a number between 1 and 7, with higher scores representing greater QOL.

Each participant underwent spirometric testing during each testing session using a Microplus handheld spirometer(*) according to American Thoracic Society guidelines.[24] Forced expiratory volume in 1 second and forced vital capacity (FVC) were measured. According to American Thoracic Society guidelines, each participant must perform a minimum of 3 [FEV.sub.1] maneuvers within 5% of each other in order to meet reliability guidelines. The reliability and validity of measurements obtained with handheld spirometry have also been assessed,[25,26] and we believed them to be sufficient for this study.

After the final testing session, participants were asked whether they would be willing to participate in the interview. Initially, all participants were asked. As the study progressed, an attempt was made to recruit participants for interviewing who represented the whole sample in terms of age, sex, and disease severity. We used this purposive sampling[27,28] in addition to the self-selection. Therefore, the participants chosen for this phase were to some extent self-selected and to some extent selected by the researchers. In accordance with qualitative methodology,[27] no attempt was made to randomly select participants or to ensure a representative sample. Each interview was conducted in the participant's home and occurred within 2 weeks of the post-rehabilitation test. All interviews were conducted by the same researcher (PGC). Participants were informed that the interview would be audiotaped and transcribed verbatim, and they were invited to review the transcript of the interview. No participant, however, requested to view a transcript. The interviewer followed a semistructured interview format, with 3 main trigger questions that focused on (1) participants' perception of the program and the changes they perceived as being due to the program, (2) the strengths and weaknesses of the program, and (3) recommendations for improving the program.

The participants were free to speak on any aspect of the pulmonary rehabilitation program, but the researcher used a list of questions to request information related to the specific topics (Tab. 2). The staff at the rehabilitation programs were not informed about which participants had agreed to do the personal interviews in order to enable each participant to speak about his or her respective program in a confidential manner.

Table 2.

Guiding Questions for the Qualitative Interviews

Main Question: What was your perception of the
program, and what changes have you noticed as a
result et the program?

What was it like?

What did you think about the education classes?

Was the information easy to understand?

Did you find the exercise challenging?

How would you describe the people who Work at the program?

How did you incorporate the information into your daily life?

What changes have you noticed since taking the program?

How is it different when you do your usual activities?

Has your shortness of breath changed? How?

Main Question: What were the strengths and
weaknesses of the program?

What was it about the program that you liked the most?

The least?

What was particularly,helpful to you and why? What was it
about the program that made it effective or ineffective?

Main Question: What recommendations do you have
far the program?

Can you suggest any changes to the exercise or education that
would make it more helpful?

Final Question: What other important information have
I not asked about? Is there something I have missed
that you feel I should know?

Data Analysis

Statistical analysis of quantitative data. The demographics of the sample, including age, sex, disease severity, and smoking history, were described using sample group means, standard deviations, and ranges. The differences between the pre-control test, pre-rehabilitation test, and post-rehabilitation test scores of the physical function and emotional function components of the CRQ and the physical summary and mental health summary components of the SF-36 were examined with a repeated-measures univariate analysis of variance using the SYSTAT statistical program.([dagger]) Although controversy exists[29] as to whether the questionnaire data should be considered interval or ordinal, Domholdt[29] noted that parametric statistics may be conducted on ordinal data provided that certain assumptions are met. We believe that, in our study, the use of parametric measures to analyze the questionnaire data was acceptable. Differences were considered to be significant at P [is less than] .01 as determined by the Bonferroni adjustment for multiple comparisons.[29] Post hoc comparisons were made with the Tukey Honestly Significant Difference test.[30]

Qualitative Analysis. The qualitative data were analyzed in accordance with established guidelines for data analysis.[27,98] In summary, the interview transcripts were first reviewed by the primary author (PGC) and 2 other qualitative researchers. These researchers are faculty members at the University of British Columbia and have over 30 years of combined experience conducting qualitative research studies. During this initial review, suggestions were made as to how future interviews could be conducted in order to obtain the most complete information about the program and any changes noticed by the participants. The primary author then coded the information into major categories: how the participants were referred to the program, the perceptions they had of the program, and what changes the participants perceived to be due to the program. The data on how the participants were referred to the program and perceptions they had of the program are reported elsewhere.[31] The changes the participants commented on were then further categorized into themes. These themes were verified and altered as necessary after reviewing subsequent transcripts and through discussion with the research team. Finally, a concept map was used to display the themes and to build a logical chain of information to illustrate any theoretical process underlying the themes. The coding was done without the use of any computer coding program. As stated previously, the interview participants did not want to review their own interviews or to review the analysis.

Results

Questionnaire and Spirometric Data

The mean scores, standard deviations, probability values, and effect size calculations[32] are presented in Table 3. Improved scores were found on 3 of the 4 questionnaire components analyzed for the CRQ and the SF-36. For the CRQ, physical function improved 22% (P [is less than] .001) and emotional function improved 10% (P [is less than] 0.001) after pulmonary rehabilitation.

Table 3. Results From the Quality-of-Life Questionnaires

                         Pre-Control

Questionnaire(a)
(Component)        [bar]X    SD     Range

CRQ
  Physical           3.9    0.90     2-5.7
  Emotional          5.0    0.94   3.2-6.8

SF-36
  Physical          38      8.4     25-55
  Mental health     53      7.7     35-65

                     Pre-Rehabilitation

Questionnaire(a)
(Component)        [bar]X    SD     Range

CRQ
  Physical           4.0    0.93   1.7-5.8
  Emotional          4.9    0.96   2.7-7

SF-36
  Physical          36      8.2     23-59
  Mental health     53      9.1     34-67

                    Post-Rehabilitation

Questionnaire(a)
(Component)        [bar]X    SD     Range

CRQ
  Physical           4.9    0.82     3-6.2
  Emotional          5.5    0.75   4.1-7

SF-36
  Physical          41      7.8     26-55
  Mental health     54      9.6     32-64

Questionnaire(a)                       Effect
(Component)          F         P      Size[31]   df

CRQ
  Physical         44.22    .000(b)   0.97(c)     2
  Emotional        11.69    .000(b)   0.63(d)     2

SF-36
  Physical          8.257   .001(b)   0.61(d)     2
  Mental health     0.323   .725      0.11(e)     2

(a) CRQ=Chronic Respiratory Questionnaire,[10] SF-36=Medical Outcomes Study 36-Item Short-Form Health Survey.[9]

(b) Statistically significant at P<.01.

(c) Large effect size.[31]

(d) Moderate effect size.[31]

(e) Negligible effect.[31]

The physical summary score of the SF-36 increased 14% after the rehabilitation phase (P=.001), whereas the mental health summary did not change (2% difference, P=.725). None of the questionnaire component scores for the CRQ and the SF-36 changed during the control phase of the study. The [FEV.sub.1] values were stable throughout the study, showing no differences among any of the 3 test points.

Qualitative Interview Results

Five women and 2 men (age 62-86 years) consented and participated in the interview portion of the study. In addition to commenting on how they were referred to the program and their opinions about pulmonary rehabilitation, the participants were able to identify several changes that they attributed to pulmonary rehabilitation. Some changes described were relatively basic in that participants learned a particular technique or fact that could be applied to their daily lives. Other changes encompassed physical, emotional, and psychological domains. When analyzing the data, a process became apparent. This process is illustrated in a concept map (Fig. 3). The concept map attempts to illustrate the movement from basic change to a more encompassing change. This process was universal among all of the interview participants.

[Figure 3 ILLUSTRATION OMITTED]

The interview participants described how they believed that acquiring certain skills and knowledge allowed them to manage their COPD more effectively. It appeared that acquiring these skills and knowledge led to greater confidence over the disease, as indicated by the following comments of the interview participants:

   I learned that Ventolin takes effect in 5 minutes or so, and the other one,
   Atrovent, it doesn't start working for about 15 minutes.... [Now I'm]
   leaving a little more time between taking the puffers ...

   I brought [my breathing] under control very shortly ... just sitting on the
   side of the bed, and just taking controlled breaths for a period, and just
   relaxing ... within 10 minutes I was okay....  [Before] I'd have been
   gasping and doing silly things ...

   I know how to control the situations I have ... I feel now confident if I
   have a shortness of breath, I can control it to the point where I don't
   have to go [to the emergency department].

Once the participants acquired the skills and knowledge and felt they had more confidence and control over their COPD, there were several comments from the participants regarding how their outlook on the future had changed and how their overall physical and emotional well-being had improved. The following quote is from a woman with very severe COPD:

   I didn't get excited about anything. I didn't think I was depressed. But I
   didn't feel great pleasure about anything, or great remorse about
   anything.... [Then] I'd been in the program ... about 3 or 4 weeks, and we
   were sitting watching television ... and it was particularly funny. And it
   just tickled my funny bone, and I started to laugh. And I couldn't stop
   laughing. And all of the sudden I looked at my husband, and he wasn't
   looking at the television. And I said, "What's the matter?" and he said,
   "You know this is the first time in about 3 years I've seen you laugh?"
   Now, it's not depression that kept me from laughing, it was fear of losing
   my breath.... [Now] it's wonderful! It's just marvelous. To hear a joke and
   laugh at it ... after years I have been able to laugh again. And enjoy.

Several interview participants had difficulty identifying precisely what aspects of the program were most beneficial. Specific education topics were not seen as necessarily more helpful than other education topics, and although the interview participants identified improvements in the energy level and physical well-being, they also felt that their improvements were due to more than just the exercise portion of the rehabilitation program.

Discussion

This study has shown that a pulmonary rehabilitation program can improve QOL in individuals with COPD. Pulmonary rehabilitation, as given in this study, is able to improve QOL by delivering exercise training, education, and coping strategy techniques to a group of motivated individuals with COPD. These conclusions are supported by the results obtained with 2 types of quantitative QOL instruments--a disease-specific questionnaire and a generic questionnaire--and by the qualitative data obtained from the interview participants.

The improvement noted in QOL, as measured by the physical function categories of the CRQ was consistent with the changes found in previous studies of pulmonary rehabilitation using the CRQ.[2,3,10,23,33-35] Comparisons of the SF-36 between this study and others are not possible due to the lack of COPD clinical trials in pulmonary rehabilitation that use the SF-36.

In addition to the improvements in physical function, the CRQ recorded changes in emotional function that are also consistent with those from previous studies.[2,10,23,36] In contrast, the mental health summary of the SF-36 did not show a difference after rehabilitation. Our results illustrate, for the people with COPD we studied, the lack of responsiveness of a generic questionnaire versus a disease-specific questionnaire. When the questions that make up this component in both questionnaires were compared, the key difference between the 2 questionnaires was that the CRQ asked the individual to measure fear, panic, and anxiety when short of breath, as well as the individual's sense of control and confidence over COPD. In contrast, the SF-36 had no questions that related to dyspnea, panic, or gaining control. It is likely that the questionnaire could not detect these changes, which may account for the relative lack of responsiveness of the mental health summary component of the SF-36.

The baseline measurements of age, sex, and disease severity of this sample were similar to those of other studies assessing pulmonary rehabilitation.[2,3,33-37] The mean age of this sample tended to be slightly older (69 years versus a mean age of 65 years calculated from the mean ages stated in the previous studies[2,3,33-35,37]) but with similar severity of lung disease. The baseline scores for the CRQ and the SF-36 were also similar to those measured in individuals with COPD in previous studies,[3,18,25,38] although the scores for the SF-36 tended to be higher (indicating a greater QOL) in this study than the norms published for COPD in the US population.[14] However, the characteristics of individuals with COPD in the US population were not provided, so comparisons between this study and the US study were limited.

It is necessary that change after an intervention be clinically important as well as statistically significant. Jaeschke et al defined the minimally clinically important difference as "the smallest difference in score in the domain of interest which patients perceive as beneficial."[39] The CRQ demonstrated changes that were calculated to be clinically important in both the physical function and emotional function components. Currently, there is no published information on the change required to be considered clinically significant or important for either the SF-36 physical or mental health summary scores.

The qualitative data from the personal interviews complemented and enhanced the data gained from the questionnaires. The interview participants noted increased energy level, confidence and control over COPD, improved emotional well-being, and an improved ability to perform certain physical activities. These improvements were reflected by the improvement in both components of the CRQ and in the physical summary component of the SF-36. However, neither questionnaire was capable of solely identifying all of these improvements, which reinforces recommendations from other researchers to incorporate both generic and disease-specific measures of QOL in a research study.[40] In addition, we believe that only qualitative research methods such as interviewing may have had the capability to identify unique issues specific to the individual or characteristics particular to a pulmonary rehabilitation program.

In 1994, National Institutes of Health called for future research to identify the respective contributions of the components of pulmonary rehabilitation, in order to determine which aspects of rehabilitation are beneficial.[1] However, research that attempts to assess the individual interventions, such as education or behavioral modifications, has shown little effect on various outcomes.[8,42] Nevertheless, the American College of Chest Physicians and the American Association of Cardiovascular and Pulmonary Rehabilitation recommended that all pulmonary rehabilitation programs continue to offer exercise, educational, and psychosocial interventions.[8,13] Components of pulmonary rehabilitation may be interactive and synergistic in their benefit. Clinical trials in which there is an attempt to analyze unique contributions of each of the various interventions alone may fail to find benefits because of the lack of synergistic effects. In this study, mixed-methods research may have addressed this difficulty by incorporating standardized questionnaires of QOL (encompassing both physical and emotional health assessment), as well as allowing some of the participants an opportunity to identify what aspects of the program were most helpful to them. It would appear that interventions that enhance an individual's sense of control over COPD can improve outcome. These interventions may include exercise, learning about medications, and learning breath control. As control was a predominant theme in the interview data, as well as being a unique feature of the CRQ (mastery) compared with the SF-36, it may be a necessary outcome to achieve in order for pulmonary rehabilitation to have a positive impact on QOL.

Although the CRQ showed a change in physical function after rehabilitation, this questionnaire does not address the ability of an individual to perform activities that are routinely performed in daily life, such as walking, climbing stairs, dressing, or bending. This may be a limitation of the questionnaire. The dyspnea domain of the CRQ measures the amount of dyspnea experienced while doing physical activities, but it does not clarify an individual's ability to perform physical activity. Improvements in activities of daily living due to improved fitness levels after pulmonary rehabilitation would not be measured by the CRQ and could be considered a threat to content validity in this questionnaire. In contrast, the SF-36 addressed physical ability. Thus, we believe that the use of both questionnaires in our study broadened the content validity of the quantitative aspect of the QOL assessment.

Limitations of the Study

There were some limitations to this study. These limitations include the lack of a random sample, the lack of participants from other ethnic backgrounds, the inability to determine the long-term benefits of pulmonary rehabilitation, and the lack of objective tests to corroborate the physical scores of the questionnaires. The additional problems of the participants saying what they think the researcher want to hear and of the Hawthorne effect[43] (participants alter behavior because of the circumstance of being studied) were also a threat to validity of the findings. However, we contend that this threat was minimized because the researcher was separate from the pulmonary rehabilitation programs and dissociated herself from them as much as possible.

The small numbers of individuals who participated in the qualitative interviews and the fact that these individuals were essentially self-selected were 2 other limitations of this study. We cannot know whether the opinions and experiences of the 7 individuals would be shared by the overall study sample of 29 people. Increasing the number of qualitative interviews would enhance the rigor of the qualitative methodology of this study.

Conclusions and Implications of This Study

We identified the manner in which QOL is affected by pulmonary rehabilitation. The questionnaires confirmed that physical health and emotional health are affected by pulmonary rehabilitation, but the concept map takes the initial step of illustrating the process of change in this study group. We believe that it may be difficult to determine the relative contributions of the components of pulmonary rehabilitation by studying each component individually. The concept map begins to address this problem of determining why pulmonary rehabilitation can be beneficial by describing how obtaining knowledge, increasing activity, and controlling dyspnea combined to enhance QOL. Future research can probe the validity of the themes in the concept map. Is this process universal among people with COPD? Does change occur in this linear fashion? Do individuals with a lesser sense of control over the disease prior to rehabilitation see the greater gain?

Clinicians can also utilize the components in the concept map in their own pulmonary rehabilitation programs. Are clinicians aware of how control issues manifest in their rehabilitation population? Merely increasing exercise workload may not be enough to improve a person's QOL. We argue that clinicians should be aware of whether a patient believes that he or she is able to cope with COPD and that improved physical function can be an effective coping strategy. Control over COPD may also influence the long-term benefits of pulmonary rehabilitation. We wonder whether those individuals who continue to feel little control over their disease and breathing after rehabilitation will lack the confidence to continue with an unsupervised exercise program. With a better understanding of how pulmonary rehabilitation programs improve QOL, researchers and clinicians can work toward designing programs that are more effective and target the specific needs of the patients.

In addition to illustrating QOL change, this study demonstrated that the CRQ appears to be a more responsive QOL instrument for people with COPD. The broad nature of the SF-36's emotional and mental health domains resulted in the inability of the questionnaire to evaluate changes in control over breathlessness and panic or anxiety experiences. This inability likely accounted for the questionnaire's apparent lack of responsiveness.

The combination of research methods that we used yielded results that, in our opinion, could not have been obtained by either method alone. The quantitative results yielded outcomes that could be applied to pulmonary rehabilitation participants in general, whereas we believe the qualitative data expanded the analysis of QOL by providing contextual information on the process of QOL change in the smaller group of 7 individuals.

Our study provides a foundation for further identification of the processes of QOL improvement after pulmonary rehabilitation in individuals with COPD, and it provides direction for research addressing the impact of diagnosis, age, ethnicity, sex, and disease severity on QOL after rehabilitation.

(*) VitalAire, 1003-7495-132 St, Surrey, British Columbia, Canada V3W 138.

([dagger]) SPSS Inc, 233 S Wacker Dr, 11th Floor, Chicago, IL 60606.

References

[1] Ries AL, Kaplan RM, Limberg TM, Prewitt LM. Effects of pulmonary rehabilitation on physiologic and psychosocial outcomes in patients with chronic obstructive pulmonary disease. Ann Intern Med. 1995;122: 823-832.

[2] Goldstein RS, Gort EH, Stubbing DG, et al. Randomised controlled trial of respiratory rehabilitation. Lancet. 1994;344(8934):1394-1397.

[3] Wijkstra PJ, Van Altena R, Kraan J, et al. Quality of life in patients with chronic obstructive pulmonary disease improves after rehabilitation at home. Eur Respir J. 1994;7:269-273.

[4] McGavin CR, Gupta SP, Lloyd EL, McHardy GJ. Physical rehabilitation for chronic bronchitis: results of a controlled trial of exercises in the home. Thorax. 1977;32:307-311.

[5] O'Donnell DE, McGuire M, Samis L, Webb KA. The impact of exercise reconditioning on breathlessness in severe chronic airflow limitation. Am J Respir Crit Care Med. 1995;152(6 pt 1):2005-2013.

[6] Reardon JZ, Awad E, Normandin E. The effect of comprehensive outpatient pulmonary rehabilitation on dyspnea. Chest. 1994;105: 1046-1052.

[7] Celli BR. Is pulmonary rehabilitation an effective treatment for chronic obstructive pulmonary disease? Yes. Am J Respir Crit Care Med. 1997;155:781-783.

[8] Pulmonary Rehabilitation Guidelines Panel, American College of Chest Physicians/American Association of Cardiovascular and Pulmonary Rehabilitation. Pulmonary rehabilitation: joint ACCP/AACVPR evidence-based guidelines. Chest. 1997;112:1363-1396.

[9] Ware JE Jr, Sherbourne CD. The MOS 36-Item Short-Form Health Survey (SF-36): conceptual framework and item selection. Med Care. 1992;30:473-483.

[10] Guyatt GH, Berman LB, Townsend M, et al. A measure of quality of life for clinical trials in chronic lung disease. Thorax. 1987;42:773-778.

[11] American Thoracic Society. Lung function testing: selection of reference values and guidelines and interpretative strategies. Am Rev Respir Dis. 1991;144:1202-1218.

[12] Burdon JG, Juniper EF, Killian KJ, et al. The perception of breathlessness in asthma. Am Rev Respir Dis. 1982;126:825-828.

[13] Gibbons WJ, Levy RD. Pulmonary rehabilitation: a breath of fresh air. In: Current Pulmonology and Critical Care Medicine. Vol 17. St Louis, Mo: Mosby-Year Book; 1996:203-231.

[14] Ware JE Jr, Kosinski M, Keller SD. SF-36 Physical & Mental Health Summary Scales: A User's Manual. 3rd ed. Boston, Mass: The Health Institute, New England Medical Center; 1994.

[15] Ware JE Jr, Kosinski M, Bayliss MS, et al. Comparison of methods for the scoring and statistical analysis of SF-36 health profile and summary measures: summary of results from the Medical Outcomes Study. Med Care. 1995;33 (suppl 4):AS264-AS279.

[16] McHorney CA, Ware JE Jr, Lu JF, Sherbourne DC. The MOS 36-Item Short-Form Health Survey (SF-36), III: tests of data quality, scaling assumptions, and reliability across diverse patients groups. Med Care. 1994;32:40-66.

[17] McHorney CA, Ware JE Jr, Raczek AE. The MOS 36-Item Short Form Health Survey (SF-36), II: psychometric and clinical tests of validity in measuring physical and mental health constructs. Med Care. 1993;31:247-263.

[18] Mahler DA, Mackowiak JI. Evaluation of the short-form 36-item questionnaire to measure health-related quality of life in patients with COPD. Chest. 1995;107:1585-1589.

[19] Viramontes JL, O'Brien B. Relationship between symptoms and health-related quality of life in chronic lung disease. J Gen Intern Med. 1994;9:46-48.

[20] Limbos MM, Chan CK, Kesten S. Quality of life in female lung transplant candidates and recipients. Chest. 1997;112:1165-1174.

[21] Guyatt GH, Townsend M, Keller J, Singer J. Should study subjects see their previous responses from a randomized control trial? J Clin Epidemiol. 1989;42:913-920.

[22] Wijkstra PJ, TenVergert EM, Van Altena R, et al. Reliability and validity of the chronic respiratory questionnaire. Thorax. 1994;49: 465-467.

[23] Guyatt GH, Berman LB, Townsend M. Long-term outcome after respiratory rehabilitation. Can Med Assoc J. 1987;137:1089-1095.

[24] American Thoracic Society. Standardization of spirometry: 1987 update. Am Rev Respir Dis. 1987;136:1285-1298.

[25] Finkelstein SM, Lindgren BR, Prasad B, et al. Reliability and validity of spirometry measurements in a paperless home monitoring diary program for lung transplantation. Heart Lung. 2000;22:523-533.

[26] Lindgren BR, Finkelstein SM, Prasad B, et al. Determination of reliability and validity in home monitoring data of pulmonary function tests following lung transplantation. Res Nurs Health. 1997;20:539-550.

[27] Morse JM. Qualitative Research Methods for Health Professionals. 2nd ed. Thousand Oaks, Calif: Sage Publications; 1995.

[28] Miles M, Huberman A. Qualitative Data Analysis: An Expanded Sourcebook. Thousand Oaks, Calif: Sage Publications; 1994.

[29] Domholdt E. Physical Therapy Research: Principles and Applications. Toronto, Ontario, Canada: WB Saunders Co; 1993.

[30] Norman GR, Streiner DL. Biostatistics: The Bare Essentials. Toronto, Ontario, Canada: Mosby-Year Book; 1994.

[31] Camp PG. Quality of Life After Respiratory Rehabilitation in Individuals With Chronic Obstructive Pulmonary Disease [master's thesis]. Vancouver, British Columbia, Canada: University of British Columbia; 1998.

[32] Cohen J. Statistical Power Analysis for the Behavioral Sciences. New York, NY: Academic Press Inc; 1977.

[33] Gerardi DA, Lovett L, Benoit-Connors ML, et al. Variables related to increased mortality following out-patient pulmonary rehabilitation. Eur Respir J. 1996;9:431-435.

[34] Holden DA, Stelmach KD, Curtis PS, et al. The impact of a rehabilitation program on functional status of patients with chronic lung disease. Respir Care. 1990;35:332-341.

[35] Vale F, Reardon JZ, ZuWallack RL. The long-term benefits of outpatient pulmonary rehabilitation on exercise endurance and quality of life. Chest. 1993;103:42-45.

[36] Fishman DB, Petty TL. Physical, symptomatic, and psychological improvement in patients receiving comprehensive care for chronic airway obstruction. J Chronic Dis. 1971;24:775-785.

[37] Couser JI Jr, Martinez FJ, Celli BR. Pulmonary rehabilitation that includes arm exercise reduces metabolic and ventilatory requirements for simple arm elevation. Chest. 1993;103:37-41.

[38] Martin LL. Validity and reliability of a quality-of-life instrument: the Chronic Respiratory Disease Questionnaire. Clin Nurs Res. 1994;3: 146-156.

[39] Jaeschke R, Singer J, Guyatt GH. Measurement of health status: ascertaining the minimal clinically important difference. Control Clin Trials. 1989;10:407-415.

[40] Patrick DL, Deyo RA. Generic and disease-specific measures in assessing health status and quality of life. Med Care. 1989;27(suppl 3):S217-S232.

[41] Fishman AP. Pulmonary rehabilitation research. Am J Respir Crit Care Med. 1994;149(3 pt 1):825-833.

[42] Toshima MT, Kaplan RM, Ries AL. Experimental evaluation of rehabilitation in chronic obstructive pulmonary disease: short-term effects on exercise endurance and health status. Health Psychol. 1990;9:237-252.

[43] Homans G. Group factors in worker productivity. In: Proshansky H, Seidenberg B, eds. Basic Studies in Social Psychology. New York, NY: Holt, Rinehart & Winston; 1965:592-604.

PG Camp, MSc, BSc (PT), is Science Researcher, Department of Medicine, Respiratory Division, University of British Columbia, Main Floor, 2775 Heather St, Vancouver, British Columbia, Canada V5Z 3J5 ([e-mail]), and Physiotherapist, St Paul's Hospital, Vancouver, British Columbia, Canada. This study was completed in partial fulfillment of the requirements for Ms Camp's Master of Science degree, School of Rehabilitation Sciences, University of British Columbia. Address all correspondence to Ms Camp.

J Appleton, RN, is Respiratory Nurse Clinician, Respiratory Rehabilitation Clinic, Saint Mary's Hospital, New Westminster, British Columbia, Canada.

WD Reid, PhD, BMR(PT), is Associate Professor, Division of Physical Therapy, School of Rehabilitation Sciences, University of British Columbia.

All authors provided writing. Ms Camp and Dr Reid provided concept/research design and data analysis, and Ms Camp provided data collection and project management. Ms Appleton and Dr Reid provided facilities and equipment. Ms Appleton provided subjects and clerical support. Dr Reid provided fund procurement, institutional liaisons, and consultation (including review of manuscript prior to submission). The authors acknowledge the Canadian Physiotherapy Cardiorespiratory Society of the Canadian Lung Association and the University of British Columbia for providing grant and studentship support, respectively.

This study was approved by the Ethics Committee, University of British Columbia.

This article was submitted August 4, 1999, and was accepted May 30, 2000.