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Rehabilitation of patients with chronic obstructive pulmonary disease. Exercise twice a week is not sufficient!
RESPIRATORY MEDICINE (2000) 94, 150±154 doi:10.1053/rmed.1999.0704, available online at http://www.idealibrary.com on
Rehabilitation of patients with chronic obstructive pulmonary disease. Exercise twice a week is not sufficient! T. J. RINGBAEK, E. BROENDUM, L. HEMMINGSEN, K. LYBECK, D. NIELSEN, C. ANDERSEN AND P. LANGE Medical department I, Copenhagen University Hospital, Bispebjerg, Denmark Several studies of chronic obstructive pulmonary disease (COPD) have shown that pulmonary rehabilitation, consisting of at least three training sessions a week, improves exercise performance and health status. This study investigates feasibility, eect and economic aspects of a rehabilitation programme consisting of two sessions a week for 8 weeks. Twenty-four patients with moderate COPD were randomized to rehabilitation and 21 to placebo. Patients were assigned to an 8-week programme of exercise plus education (Exercise group) or conventional community care (Placebo group). The rehabilitation program was carried out in a hospital outpatient setting and consisted of 16 h exercise and 13.5 h of education. The exercise group received physiotherapy and education twice a week. Seven patients did not complete the programme. The characteristics of the 38 COPD-patients at baseline were the following: (mean+SD) forced expiratory volume in 1 sec (FEV1) 11+04 l (47% of predicted), 6-min walking distance (6MWD) 413+75 m, score of St. George's Respiratory Questionnaire (SGRQ) 44+21. Health-status, assessed by SGRQ and The Psychological General Well-being (PGWB) Index, did not improve. Rehabilitation resulted in an insigni®cant improvement in the 6MWD [29 m (95% con®dence interval: 78 766 m)]. We conclude that a rehabilitation program consisting of exercise and education twice a week for 8 weeks had no eect on exercise performance and well being in patients with moderate COPD. RESPIR. MED. (2000) 94, 150±154
Introduction Pulmonary rehabilitation is a set of tools and disciplines which is applied to diminish, and at best revert, the pathophysiological mechanisms causing low physical capacity and reduced life quality in patients with chronic obstructive pulmonary disease (COPD). Important elements of pulmonary rehabilitation (PR) are smoking cessation, optimal medical treatment, focus on psychosocial mechanisms, self-control occupational therapy, nutritional therapy and exercise (1,2). For many years, the ®rst two elements have been the corner-stone in the treatment of patients with COPD, whereas the other elements are new areas where little investigation has been carried out. Studies have shown that PR with exercise 3±7 times weekly improves quality of life and exercise tolerance in patients with moderate COPD (3±8). In a study without a control group, exercise with high intensity resulted in a signi®cantly more increased exercise tolerance (9). Yet at Received 4 August 1999 and accepted 22 September 1999 Correspondence should be addressed to: Thomas J. Ringbaek, Moseskraenten 17,3140 Aalsgaarde E-mail: [email protected]
0954-6111/00/020150+05 $35?00/0
# 2000 HARCOURT PUBLISHERS LTD
present, the required intensity and frequency of exercise are not clari®ed. The aim of this controlled study was to evaluate the eect of a rehabilitation programme consisting of exercise twice a week with moderate intensity in moderate COPD. In addition the study focused on aspects of recruitment and economy in pulmonary rehabilitation.
Patients and methods PATIENTS For a period of 6 months, patients were recruited from the outpatient clinic of Bispebjerg Hospital. The entry criteria were: stable COPD with FEV1/FVC-ratio 570%, FEV1 406, age 575 years and an oxygen saturation without oxygen supply 490%. Patients were excluded if they participated in an exercise programme, had another serious disease, such as cancer, had home oxygen therapy, were senile or suered from a psychiatric disorder, or were dependent on walking equipment. Of 130 contacted patients 48 entered. Three of the patients were excluded due to very low FEV1. In a randomized and controlled # 2000 HARCOURT PUBLISHERS LTD
REHABILITATION OF PATIENTS WITH COPD study, 24 patients were allocated to a pulmonary rehabilitation (active group), whereas the remaining 21 patients acted as a control group. The active group was divided into a spring and an autumn-team, each with 12 patients. The local ethical committee approved the study and all patients gave their informed written consent.
151
assessed by means of the St. George's Respiratory Questionnaire (SGRQ) and by means of the Psychological General Well-being (PGWB) index (12,13). Quality of life scores, 6-min walking test and Borg dyspnoea-score were evaluated before and after the 8 weeks.
STATISTICS
REHABILITATION PROGRAMME The programme consisted of 2 weekly sessions of 2 h for 8 weeks. Patients trained together at the hospital for 1 h each time. The exercise was conducted by a physiotherapist and consisted of warming-up, mobility training, coordination tests, dynamic strength exercise of upper and lower extremities and abdominal musculature, stair climbing and jogging as endurance training, stretching and relaxation. The intensity and load of the exercise were individualized so the patients achieved a dyspnoea-score of 4±5 on a scale to 10 (10). Patients were instructed in using pursed-lip breathing during exercise. In the remaining hours, patients were educated in the dierent aspects of COPD by a doctor and a nurse. They received counselling by a nutritional therapist and by an occupational therapist. Patients were delivered elastic bands and a copy of the training programme, so they could train at home. To succeed, the patients had to participate in at least half of the programme.
EFFECT PARAMETERS Patients were asked to walk as far as possible for 6 min with standardized pacing (11) along a 30 m corridor (6-min walking test). Dyspnoea was measured before and after the walking test on the Borg scale (10). Quality of life was
For each outcome, an unpaired t-test of the dierence between baseline and follow-up in the active group vs. the control group was done. The 95%-con®dence interval around mean dierences was calculated. SPSS version 80 (SPSS Inc., Chicago, IL, U.S.A.) was used.
Results Of the 24 patients in the active group, seven did not complete the programme: three due to exacerbation in COPD, two due to myalgia, one due to lack of time and one gave no reason. With regard to baseline characteristics, these patients did not dier from the patients who completed the rehabilitation. The majority of patients were females who had a moderate degree of COPD (Table 1). In the active group signi®cantly more patients were females, were current smokers and had a better 6-min walking test as compared with the control group. In both the active and control groups, 6-min walking distance and symptom-score were unchanged after 8 weeks and there was no dierence between the two groups (Table 2). A total of 90 sta-hours were used in the study: nurses (30), doctors (18), physiotherapist (36), nutritional therapist (3) and occupational therapist (3). The salary amounted to approximately 2000 US $. Eight patients required transportation arranged by the hospital at approx. 1800 US $.
TABLE 1. Characteristics of the patients at baseline
Age (years) Gender (male/female) FEV1(% of predicted value) Pulse saturation of oxygen (%) Current smoking (yes/no) CO in expired air (ppm) Body Mass Index (kg m72) Steroid per os (yes/no) Steroid inhaled (yes/no) Borg dyspnoea-score at rest Borg dyspnea-score after walking Change in dyspnea-score 6-MWD (m) PGWB-index SGRQ-total score
Active (n24)
Control (n21)
P-value
618+68 1/23 495+174 953+16 16/8 13 (1±41) 261+56 3/21 19/5 12+14 49+19 36+17 377+78 068+015 477+159
646+77 6/15 443+137 953+13 7/14 4 (1±42) 241+36 3/18 15/6 09+10 49+20 40+19 433+62 072+013 422+157
n.s. 0039 n.s. n.s. 0038 n.s. n.s. n.s. n.s. n.s. n.s. n.s. 0013 n.s. n.s.
Mean+SD is indicated for continuous variables, except for CO in expired air, where median (range) is indicated. n.s.: nonsigni®cant.
152
T. J. RINGBAEK ET AL.
TABLE 2. Eect of rehabilitation assessed by symptoms and 6-min walking test
Change Change Change Change Change
in in in in in
6-MWD (m) PGWB-index SGRQ-score dyspnea-score, rest dyspnoea-score, after walking test
Active (n17)
Control (n21)
Dierence (95% CI)
105+450 0049+013 721+181 04+17 707+30
7185+620 70012+011 721+106 09+13 711+14
290 (781±661) 006 (70021±0142) 01 (798±100) 705 (715±06) 05 (71.1±21)
Mean+SD. CI: Con®dence interval. Two patients in the control group failed to appear at the 8-week re-test.
Expenses of equipment were very low. As the space accommodation was disposed freely by the hospital, the cost of rent was not included.
Discussion In this study, we were not able to ®nd a signi®cant eect of pulmonary rehabilitation on physical performance and well being. As this is inconsistent with previous ®ndings (3±8), it is natural to consider a number of possible causes: selection of patients, type II-error, short duration of the training programme, low intensity, low frequency and dierent compositions of the training programme. Finally, one could speculate that the chosen eect parameters were too insensitive. In the following the above mentioned items will be discussed.
SELECTION OF PATIENTS Our inclusion and exclusion criteria did not dier essentially from the criteria applied in other studies of pulmonary rehabilitation (4,6). The criteria were perhaps less restrictive and in practice only patients with severe COPD were excluded. Eligible patients were easily found, but surprisingly few patients were interested. Thus, we had to contact 130 patients in order to randomize 45. Not all of the previous studies explained how the patients were recruited but, in general, one has to evaluate three patients for each randomized patient (6±8, 14). On the other hand if the patients were referred for a purpose of rehabilitation, and therefore highly motivated, up to 90% of the patients could be randomized (4). As re¯ected by distribution of gender among patients, we found it dicult to motivate males to rehabilitation, but otherwise our patients were not dierent from patients in the studies where eect of rehabilitation was shown. In the control group, more patients were females and current smokers, and they had a higher 6-min walking distance at randomization as compared with the active group. So far, the in¯uence of gender and smoking habits on pulmonary rehabilitation has not been evaluated. In an uncontrolled study, the eect of rehabilitation, assessed by the 6-min walking distance, was inversely proportional with the initial distance (15). Patients with severe dyspnoea seemed to gain no or very little bene®t of the pulmonary
rehabilitation (4,16). Yet in our study, in spite of quite low FEV1 patients in both groups had very little dyspnoea and symptoms as compared with patients, who bene®ted from the rehabilitation programme in the above mentioned studies (4,16). In case of a type II-error an eect of rehabilitation can be missed. Our study was dimensioned to detect a change in 6min walking distance and symptom-score of about 13%, which should be sucient to be of clinical relevance (17,18). As other studies, with fewer patients, had been able to shown an eect, we believe that type II-error is not a problem in our study (3,5,6,14).
EFFECT PARAMETERS The 6-min walking test and SGRQ are both approved outcomes. Two meta-analyses have shown that rehabilitation has a signi®cant and clinical relevant eect on healthrelated quality of life and exercise tolerance (19). However, a certain relationship between these eects has not been shown (4). Besides improved exercise tolerance, other factors like better self-control and increased activities of daily living through occupational counselling and establishment of social contacts are expected to improve the quality of life. In connection with pulmonary rehabilitation few studies have evaluated the long-term eect on the quality of life. The results are ambiguous. In a study of 119 patients, Ries et al. found a modest decreasing eect after 2 months, while Bredstrup et al. found an increasing eect 12 weeks after the end of the rehabilitation programme (6,7). Both studies encouraged the patients to continue exercise at home.
DURATION, FREQUENCY, INTENSITY AND COMPOSITION OF THE TRAINING PROGRAMME According to the literature, 8 weeks of pulmonary rehabilitation is sucient, and the elements and the intensity of the exercise in our study did not dier from other studies, where rehabilitation has bene®tted the patients (4,5,7). Among selected randomized and controlled studies in an outpatient setting, the eect of rehabilitation, assessed by the walking endurance, varies from 7% (in our study) to 54% with increasing frequency of exercise (Fig. 1).
REHABILITATION OF PATIENTS WITH COPD
153
exercise at least 3 times a week should be included in the future programmes.
Acknowledgements Thanks to the Danish Lung Association and The Prevention Poll of Bispebjerg Hospital for economic support. Thanks to the nurse, Pia Munck, for re-testing the patients.
References
FIG. 1. The in¯uence of the exercise frequency on the 6min walking distance. Each dot represents a placebocontrolled study on pulmonary rehabilitation in an outpatient setting with a 6-min walking distance as an outcome. The numbers of the references are displayed. In two studies, the 6MWD was calculated as 50% of the 12min walking distance (3,5). BBH: Bispebjerg Hospital Study.
However, our study diers from the other studies by only having two exercise sessions a week. The negative results of our study could thus be interpreted as a support for the recommendation, that patients have to exercise at least every second day (2).
ECONOMY When a new treatment is introduced, considerations about cost-eectiveness ought to be done. Very few studies report on costs of rehabilitation programmes. As clear instruction of how to calculate costs does not exist, one should be cautious about making a comparison. In a previous Danish study, 124 sta-hours were required in a programme of 12 weeks with 16 patients (6). In Denmark, the cost of salary to the sta is estimated at 8 US $ h71 patient71. Thus, the cost of a programme with exercise three times a week for 10 weeks would be about 3800 US $ without inclusion of the cost of transportation and accommodation.
Conclusion Pulmonary rehabilitation is directed to a selected group of patients with COPD. Only a third of the contacted patients was interested and only three quarters of the included patients completed the programme. Patients with a moderate degree of COPD did not bene®t from a rehabilitation programme of 8 weeks with 2 weekly sessions. As we think that low frequency of exercise is most probably the cause of this failure, we recommend that
1. Celli BR. Pulmonary rehabilitation in patients with copd. Am J Respir Crit Care Med 1995; 152: 861±864. 2. Mahler DA. Pulmonal rehabilitation. Chest 1998; 113: 263S±268S. 3. Sinclair DJM, Ingram CG. Controlled trial of supervised exercise training in chronic bronchitis. Br Med J 1980; 280: 519±521. 4. Wedzicha JA, Bestall, Garrod R, Garnham R, Paul EA, Jones PW. Randomized controlled trial of pulmonary rehabilitation in severe chronic obstructive pulmonary disease patients, strati®ed with the MRC dyspnoea scale. Eur Respir J 1998; 12: 363±369. 5. Cockcroft AE, Saunders MJ, Berry G. Randomised controlled trial of rehabilitation in chronic respiratory disability. Thorax 1981; 36: 200±203. 6. Bredstrup KE, Ingemann Jensen J, Holm S, Bengtsson B. Out-patient rehabilitation improves activities of daily living, quality of life and exercise tolerance in chronic obstructive pulmonary disease. Eur Respir J 1997; 10: 2801±2806. 7. Ries AL, Kaplan RM, Limberg TM, Prewitt LM. Eects of pulmonary rehabilitation on physiologic and psychosocial outcomes in patients with chronic obstructive pulmonary disease. Ann Interm Med 1985; 122: 823±832. 8. Goldstein RS, Gort EH, Stubbing D, Avendano MA, Guyatt GH. Randomised controlled trial of respiratory rehabilitation. Lancet 1994; 344: 1394±1397. 9. Casaburi R, Patessio A, Ioli F, Zanaboni S, Donner C, Wasserman K. Reduction in exercise lactic acidosis and ventilation as a result of exercise training in patients with obstructive lung disease. Am Rev Respir Dis 1991; 143: 9±18. 10. Borg GAV. Psychophysical bases of perceived exertion. Med Sci Sports Exerc 1982; 14: 377±381. 11. Guyatt GH, Pugsley SO, Sullivan M, et al. Eect of encouragement on walking test performance. Thorax 1984; 39: 818±822. 12. Jones PW, Quirk FH, Baveystock CM, et al. A self complete measure for chonic air¯ow limitation Ð the St George's Respiratory Questionnaire. Am Rev Respir Dis 1992; 145: 1321±1327. 13. Dubuy HJ. The psychological General Well-Being (PGWB) Index. In: Wenger NK, Mattson ME, Furberg CF, Elinson JA eds. Assessment of quality of life in clinical trials of cardiovascular therapies. New York: LeJacq, 1984: 170±183.
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14. Simpson K, Killian K, McCartney, Stubbing DG, Jones NL. Randomised controlled trial of weightlifting exercise in patients with chronic air¯ow limitation. Thorax 1992; 47: 70±75. 15. ZuWallack RL, Patel K, Reardon JZ, Clark III BA, Normandin EA. Predictors of improvement in the 12minute walking distance following a six-week outpatient pulmonary rehabilitation program. Chest 1991; 99: 805±808. 16. Ketelaars CAJ, Abu-Saad HH, SchloÈsser MAG, Mostert R, Wouters EFM. Long-term outcome of pulmonary rehabilitation in patients with COPD. Chest 1997; 112: 363±369.
17. Jaeschke R, Singer J, Guyatt GH. Measurement of health status. Ascertaining the minimal clinically important dierence. Control Clin Trials 1989; 10: 407±415. 18. Goldstein RS, Redelmeier DA, Baksh L, Guyatt GH. Subjective comparison ratings of walking ability in patients with COPD. Proceedings f the 5th International Conference on Pulmonary Rehabilitation and Home Ventilation. Denver, Colorado, 1995: 99. 19. Lacasse Y, Wong E, Guyatt GH, King D, Cook DJ, Goldstein RS. Meta-analysis of respiratory rehabilitation in chronic obstructive pulmonary disease. Lancet 1996; 348: 1115±1119.
Rehabilitation of patients with chronic obstructive pulmonary disease. Exercise twice a week is not sufficient! T. J. RINGBAEK, E. BROENDUM, L. HEMMINGSEN, K. LYBECK, D. NIELSEN, C. ANDERSEN AND P. LANGE Medical department I, Copenhagen University Hospital, Bispebjerg, Denmark Several studies of chronic obstructive pulmonary disease (COPD) have shown that pulmonary rehabilitation, consisting of at least three training sessions a week, improves exercise performance and health status. This study investigates feasibility, eect and economic aspects of a rehabilitation programme consisting of two sessions a week for 8 weeks. Twenty-four patients with moderate COPD were randomized to rehabilitation and 21 to placebo. Patients were assigned to an 8-week programme of exercise plus education (Exercise group) or conventional community care (Placebo group). The rehabilitation program was carried out in a hospital outpatient setting and consisted of 16 h exercise and 13.5 h of education. The exercise group received physiotherapy and education twice a week. Seven patients did not complete the programme. The characteristics of the 38 COPD-patients at baseline were the following: (mean+SD) forced expiratory volume in 1 sec (FEV1) 11+04 l (47% of predicted), 6-min walking distance (6MWD) 413+75 m, score of St. George's Respiratory Questionnaire (SGRQ) 44+21. Health-status, assessed by SGRQ and The Psychological General Well-being (PGWB) Index, did not improve. Rehabilitation resulted in an insigni®cant improvement in the 6MWD [29 m (95% con®dence interval: 78 766 m)]. We conclude that a rehabilitation program consisting of exercise and education twice a week for 8 weeks had no eect on exercise performance and well being in patients with moderate COPD. RESPIR. MED. (2000) 94, 150±154
Introduction Pulmonary rehabilitation is a set of tools and disciplines which is applied to diminish, and at best revert, the pathophysiological mechanisms causing low physical capacity and reduced life quality in patients with chronic obstructive pulmonary disease (COPD). Important elements of pulmonary rehabilitation (PR) are smoking cessation, optimal medical treatment, focus on psychosocial mechanisms, self-control occupational therapy, nutritional therapy and exercise (1,2). For many years, the ®rst two elements have been the corner-stone in the treatment of patients with COPD, whereas the other elements are new areas where little investigation has been carried out. Studies have shown that PR with exercise 3±7 times weekly improves quality of life and exercise tolerance in patients with moderate COPD (3±8). In a study without a control group, exercise with high intensity resulted in a signi®cantly more increased exercise tolerance (9). Yet at Received 4 August 1999 and accepted 22 September 1999 Correspondence should be addressed to: Thomas J. Ringbaek, Moseskraenten 17,3140 Aalsgaarde E-mail: [email protected]
0954-6111/00/020150+05 $35?00/0
# 2000 HARCOURT PUBLISHERS LTD
present, the required intensity and frequency of exercise are not clari®ed. The aim of this controlled study was to evaluate the eect of a rehabilitation programme consisting of exercise twice a week with moderate intensity in moderate COPD. In addition the study focused on aspects of recruitment and economy in pulmonary rehabilitation.
Patients and methods PATIENTS For a period of 6 months, patients were recruited from the outpatient clinic of Bispebjerg Hospital. The entry criteria were: stable COPD with FEV1/FVC-ratio 570%, FEV1 406, age 575 years and an oxygen saturation without oxygen supply 490%. Patients were excluded if they participated in an exercise programme, had another serious disease, such as cancer, had home oxygen therapy, were senile or suered from a psychiatric disorder, or were dependent on walking equipment. Of 130 contacted patients 48 entered. Three of the patients were excluded due to very low FEV1. In a randomized and controlled # 2000 HARCOURT PUBLISHERS LTD
REHABILITATION OF PATIENTS WITH COPD study, 24 patients were allocated to a pulmonary rehabilitation (active group), whereas the remaining 21 patients acted as a control group. The active group was divided into a spring and an autumn-team, each with 12 patients. The local ethical committee approved the study and all patients gave their informed written consent.
151
assessed by means of the St. George's Respiratory Questionnaire (SGRQ) and by means of the Psychological General Well-being (PGWB) index (12,13). Quality of life scores, 6-min walking test and Borg dyspnoea-score were evaluated before and after the 8 weeks.
STATISTICS
REHABILITATION PROGRAMME The programme consisted of 2 weekly sessions of 2 h for 8 weeks. Patients trained together at the hospital for 1 h each time. The exercise was conducted by a physiotherapist and consisted of warming-up, mobility training, coordination tests, dynamic strength exercise of upper and lower extremities and abdominal musculature, stair climbing and jogging as endurance training, stretching and relaxation. The intensity and load of the exercise were individualized so the patients achieved a dyspnoea-score of 4±5 on a scale to 10 (10). Patients were instructed in using pursed-lip breathing during exercise. In the remaining hours, patients were educated in the dierent aspects of COPD by a doctor and a nurse. They received counselling by a nutritional therapist and by an occupational therapist. Patients were delivered elastic bands and a copy of the training programme, so they could train at home. To succeed, the patients had to participate in at least half of the programme.
EFFECT PARAMETERS Patients were asked to walk as far as possible for 6 min with standardized pacing (11) along a 30 m corridor (6-min walking test). Dyspnoea was measured before and after the walking test on the Borg scale (10). Quality of life was
For each outcome, an unpaired t-test of the dierence between baseline and follow-up in the active group vs. the control group was done. The 95%-con®dence interval around mean dierences was calculated. SPSS version 80 (SPSS Inc., Chicago, IL, U.S.A.) was used.
Results Of the 24 patients in the active group, seven did not complete the programme: three due to exacerbation in COPD, two due to myalgia, one due to lack of time and one gave no reason. With regard to baseline characteristics, these patients did not dier from the patients who completed the rehabilitation. The majority of patients were females who had a moderate degree of COPD (Table 1). In the active group signi®cantly more patients were females, were current smokers and had a better 6-min walking test as compared with the control group. In both the active and control groups, 6-min walking distance and symptom-score were unchanged after 8 weeks and there was no dierence between the two groups (Table 2). A total of 90 sta-hours were used in the study: nurses (30), doctors (18), physiotherapist (36), nutritional therapist (3) and occupational therapist (3). The salary amounted to approximately 2000 US $. Eight patients required transportation arranged by the hospital at approx. 1800 US $.
TABLE 1. Characteristics of the patients at baseline
Age (years) Gender (male/female) FEV1(% of predicted value) Pulse saturation of oxygen (%) Current smoking (yes/no) CO in expired air (ppm) Body Mass Index (kg m72) Steroid per os (yes/no) Steroid inhaled (yes/no) Borg dyspnoea-score at rest Borg dyspnea-score after walking Change in dyspnea-score 6-MWD (m) PGWB-index SGRQ-total score
Active (n24)
Control (n21)
P-value
618+68 1/23 495+174 953+16 16/8 13 (1±41) 261+56 3/21 19/5 12+14 49+19 36+17 377+78 068+015 477+159
646+77 6/15 443+137 953+13 7/14 4 (1±42) 241+36 3/18 15/6 09+10 49+20 40+19 433+62 072+013 422+157
n.s. 0039 n.s. n.s. 0038 n.s. n.s. n.s. n.s. n.s. n.s. n.s. 0013 n.s. n.s.
Mean+SD is indicated for continuous variables, except for CO in expired air, where median (range) is indicated. n.s.: nonsigni®cant.
152
T. J. RINGBAEK ET AL.
TABLE 2. Eect of rehabilitation assessed by symptoms and 6-min walking test
Change Change Change Change Change
in in in in in
6-MWD (m) PGWB-index SGRQ-score dyspnea-score, rest dyspnoea-score, after walking test
Active (n17)
Control (n21)
Dierence (95% CI)
105+450 0049+013 721+181 04+17 707+30
7185+620 70012+011 721+106 09+13 711+14
290 (781±661) 006 (70021±0142) 01 (798±100) 705 (715±06) 05 (71.1±21)
Mean+SD. CI: Con®dence interval. Two patients in the control group failed to appear at the 8-week re-test.
Expenses of equipment were very low. As the space accommodation was disposed freely by the hospital, the cost of rent was not included.
Discussion In this study, we were not able to ®nd a signi®cant eect of pulmonary rehabilitation on physical performance and well being. As this is inconsistent with previous ®ndings (3±8), it is natural to consider a number of possible causes: selection of patients, type II-error, short duration of the training programme, low intensity, low frequency and dierent compositions of the training programme. Finally, one could speculate that the chosen eect parameters were too insensitive. In the following the above mentioned items will be discussed.
SELECTION OF PATIENTS Our inclusion and exclusion criteria did not dier essentially from the criteria applied in other studies of pulmonary rehabilitation (4,6). The criteria were perhaps less restrictive and in practice only patients with severe COPD were excluded. Eligible patients were easily found, but surprisingly few patients were interested. Thus, we had to contact 130 patients in order to randomize 45. Not all of the previous studies explained how the patients were recruited but, in general, one has to evaluate three patients for each randomized patient (6±8, 14). On the other hand if the patients were referred for a purpose of rehabilitation, and therefore highly motivated, up to 90% of the patients could be randomized (4). As re¯ected by distribution of gender among patients, we found it dicult to motivate males to rehabilitation, but otherwise our patients were not dierent from patients in the studies where eect of rehabilitation was shown. In the control group, more patients were females and current smokers, and they had a higher 6-min walking distance at randomization as compared with the active group. So far, the in¯uence of gender and smoking habits on pulmonary rehabilitation has not been evaluated. In an uncontrolled study, the eect of rehabilitation, assessed by the 6-min walking distance, was inversely proportional with the initial distance (15). Patients with severe dyspnoea seemed to gain no or very little bene®t of the pulmonary
rehabilitation (4,16). Yet in our study, in spite of quite low FEV1 patients in both groups had very little dyspnoea and symptoms as compared with patients, who bene®ted from the rehabilitation programme in the above mentioned studies (4,16). In case of a type II-error an eect of rehabilitation can be missed. Our study was dimensioned to detect a change in 6min walking distance and symptom-score of about 13%, which should be sucient to be of clinical relevance (17,18). As other studies, with fewer patients, had been able to shown an eect, we believe that type II-error is not a problem in our study (3,5,6,14).
EFFECT PARAMETERS The 6-min walking test and SGRQ are both approved outcomes. Two meta-analyses have shown that rehabilitation has a signi®cant and clinical relevant eect on healthrelated quality of life and exercise tolerance (19). However, a certain relationship between these eects has not been shown (4). Besides improved exercise tolerance, other factors like better self-control and increased activities of daily living through occupational counselling and establishment of social contacts are expected to improve the quality of life. In connection with pulmonary rehabilitation few studies have evaluated the long-term eect on the quality of life. The results are ambiguous. In a study of 119 patients, Ries et al. found a modest decreasing eect after 2 months, while Bredstrup et al. found an increasing eect 12 weeks after the end of the rehabilitation programme (6,7). Both studies encouraged the patients to continue exercise at home.
DURATION, FREQUENCY, INTENSITY AND COMPOSITION OF THE TRAINING PROGRAMME According to the literature, 8 weeks of pulmonary rehabilitation is sucient, and the elements and the intensity of the exercise in our study did not dier from other studies, where rehabilitation has bene®tted the patients (4,5,7). Among selected randomized and controlled studies in an outpatient setting, the eect of rehabilitation, assessed by the walking endurance, varies from 7% (in our study) to 54% with increasing frequency of exercise (Fig. 1).
REHABILITATION OF PATIENTS WITH COPD
153
exercise at least 3 times a week should be included in the future programmes.
Acknowledgements Thanks to the Danish Lung Association and The Prevention Poll of Bispebjerg Hospital for economic support. Thanks to the nurse, Pia Munck, for re-testing the patients.
References
FIG. 1. The in¯uence of the exercise frequency on the 6min walking distance. Each dot represents a placebocontrolled study on pulmonary rehabilitation in an outpatient setting with a 6-min walking distance as an outcome. The numbers of the references are displayed. In two studies, the 6MWD was calculated as 50% of the 12min walking distance (3,5). BBH: Bispebjerg Hospital Study.
However, our study diers from the other studies by only having two exercise sessions a week. The negative results of our study could thus be interpreted as a support for the recommendation, that patients have to exercise at least every second day (2).
ECONOMY When a new treatment is introduced, considerations about cost-eectiveness ought to be done. Very few studies report on costs of rehabilitation programmes. As clear instruction of how to calculate costs does not exist, one should be cautious about making a comparison. In a previous Danish study, 124 sta-hours were required in a programme of 12 weeks with 16 patients (6). In Denmark, the cost of salary to the sta is estimated at 8 US $ h71 patient71. Thus, the cost of a programme with exercise three times a week for 10 weeks would be about 3800 US $ without inclusion of the cost of transportation and accommodation.
Conclusion Pulmonary rehabilitation is directed to a selected group of patients with COPD. Only a third of the contacted patients was interested and only three quarters of the included patients completed the programme. Patients with a moderate degree of COPD did not bene®t from a rehabilitation programme of 8 weeks with 2 weekly sessions. As we think that low frequency of exercise is most probably the cause of this failure, we recommend that
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