Heerema-Poelman, Ankie PT; Stuive, Ilse PhD; Wempe, Johan B. MD, PhD
The beneficial effects of pulmonary rehabilitation (PR) in patients with chronic obstructive pulmonary disease (COPD) are well established in terms of improved exercise performance and health-related quality of life (HRQOL), a reduction in dyspnea and fatigue, a reduced number of hospitalizations, and reduced levels of anxiety and depression.1–4 Positive results of PR, however, appear to diminish gradually over 6 to 12 months5–9 and with postrehabilitation interventions over 1 to 2 years.10,11 Adopting an active lifestyle after PR results in a better maintenance of the positive effects of PR.12–14 Nevertheless, exercise adherence in general is known to be poor especially in patients with pulmonary conditions (50%-60%).15,16 This exercise nonadherence results in adverse health outcomes, including increased rate of exacerbations and hospitalizations and probably increased mortality.17,18
To stimulate exercise adherence, several PR maintenance exercise programs have been evaluated. Most studies showed no improvements on adherence after a maintenance program.8,19,20 Reasons for nonadherence were relapse due to exacerbations, difficulty in restarting exercising again, weather conditions, removal of supervision, and lack of group support. Positive results are reported on stimulation of regular walking12 and value of distractive auditory stimuli during exercise.21
COPD is progressive and deteriorating in nature, and perceived frailty, poor health, and exacerbations are mentioned as the main personal barriers to adherence to prescribed home exercises.8,19,22 The influence of psychological factors such as anxiety and depression on adherence are also mentioned.23 Next to these factors, illness perceptions and self-efficacy may play a role in adherence. Illness perceptions are associated with functional status and disability, psychological outcomes, and HRQOL.24 Changing maladaptive illness perceptions such as those concerning personal and treatment control had a positive influence on exercise capacity and HRQOL.25 Illness perceptions may therefore have a positive influence on adherence to a maintenance program. In addition, exercise self-efficacy, reflecting how people feel, think, and motivate themselves to continue regular exercise, is an important part of the health behavior change during and after PR. Improving exercise self-efficacy may facilitate adherence to a maintenance program.12,15,26
The purpose of this study was twofold: (1) to investigate how many patients with COPD were adherent to a maintenance exercise program developed in our rehabilitation center, 1 year after finishing PR; and (2) to explore predictors of nonadherence to the maintenance program. Patients with COPD were referred to maintenance programs in their local area immediately after PR, supervised by primary care physiotherapists experienced in COPD treatment. Regular supervision, with no limitation in duration, was provided to enhance adherence to exercise training,11,27–32 especially after exacerbations.31–33 The following variables were expected to be predictive for nonadherence: health status (forced expiratory volume in 1 second [FEV1], total lung capacity [TLC], and exacerbations),8,33 walking distance, exercise self-efficacy, the influence of anxiety and depression, HRQOL, and illness perceptions of personal and treatment control.
Patients with the diagnosis of COPD were recruited from the rehabilitation center, between August 2008 and December 2009. PR was individually and interdisciplinary tailored to the needs of the patient, combining an exercise training program, breathing exercises, psychological support, and education on knowledge of COPD, early recognition and treatment of exacerbations, and the importance of exercise. The length of the program varied per patient (9–12 weeks, 3 days a week), depending on the attainment of patient-specific goals. Included in the study were patients who had successfully completed the initial PR program, were able to fill out questionnaires, and were willing to comply with the maintenance program. Excluded were patients with progressive diseases interfering with short-term life expectancy, such as malignancies and unstable heart disease. All patients gave their written informed consent and the study was approved by the medical ethics review board of the Medical Center Groningen.
After PR, patients were referred to a home-care maintenance exercise program in selected primary care settings. The maintenance programs were supervised by primary care physiotherapists with extended knowledge of exercise training of patients with COPD. Therefore, a network of primary care physiotherapists was identified, who were trained in COPD management and had regular educational meetings in our rehabilitation center. The maintenance program had to match the content of the PR program, which was executed according to American Thoracic Society/European Respiratory Society guidelines,34 and consisted of whole-body endurance training, interval training, and resistance training. Physiotherapists obtained written information regarding the course of PR of each patient, and recommendations for continuing exercise training were provided.
The main outcome parameter was adherence (adherent/nonadherent) to the maintenance exercise program, where adherence was defined as attending the maintenance program for 1 year. After 6 months, all patients were contacted by telephone to inquire whether they had kept up their maintenance exercise programs. Dropouts at 6 months received the self-reported questionnaire. They were asked to describe the reasons for nonadherence, such as experiencing exacerbations, lack of motivation, financial burden, or distance problems, and what they would have needed to be adherent. After 12 months, the remaining patients received the self-reported questionnaire to evaluate adherence, also including patient-reported reasons for nonadherence, such as satisfaction with the maintenance program. Patient characteristics, for example, age, gender, Global Initiative for Chronic Obstructive Lung Disease (GOLD) class, and educational level (low, mid, high), were gathered from medical status and by questions in the self-reported questionnaire. The predictor variables, except exacerbations and duration of rehabilitation, were measured using standardized instruments in the last week of PR.
FEV1 and TLC were obtained by spirometry and body plethysmography, following American Thoracic Society/European Respiratory Society guidelines.33 Forced expiratory volume in 1 second, % predicted (FEV1 % pred), was also obtained but not included as a predictor because of the high correlation with FEV1. Lower FEV1 and higher TLC are signs of progressive disease and were expected to be associated with a greater chance of drop-out from the maintenance program.
Exercise capacity was measured by the Incremental Shuttle Walk Test (ISWT), which is reliable and valid in patients with COPD.35 The ISWT measures walking distance with an increasing speed limit. A higher score reflects better mobility of patients with COPD, seems to be a predictor of survival, and may therefore positively influence adherence.36
Exercise self-efficacy was measured by the Exercise Self-Regulatory Efficacy Scale, which is a reliable and valid instrument to assess behaviors related to exercise self-efficacy in patients with COPD.37 Patients have to indicate on a scale from 0% to 100% how certain they are to continue exercising regularly under 16 different situations (items). A higher score on self-efficacy was expected to be associated with enhanced adherence to a maintenance exercise program.
Illness perceptions of treatment and personal control were measured using 2 subscales from the Illness Perception Questionnaire–Revised. High scores on personal and treatment control represent positive beliefs about the controllability of the illness and a personal understanding of the condition and, thus, are expected to be associated with a higher level of adherence.24 The Illness Perception Questionnaire–Revised is a reliable and valid measure and used in patients with COPD.38,39
Health-related quality of life was measured by the St George's Respiratory Questionnaire, which is a reliable and valid instrument to measure health status in patients with COPD.40 It consists of 3 parts: symptoms, activity, and impacts.25 A higher score is associated with more experienced health impairments.
Anxiety and depression were measured by the Hospital Anxiety and Depression Scale (HADS). The 14 items indicate the possible presence of anxiety and depressive symptoms.41 Higher scores represent more symptoms or more severe symptoms.28,42 The HADS is a reliable and valid instrument,43,44 and the Dutch version has been validated on an elderly population41 and is frequently used in patients with COPD.45,46
Duration of PR was measured by reviewing patient records and depended upon clinical judgment of the rehabilitation team. As behavior change is also an important topic in PR, a longer duration of PR was expected to be a predictor of better adherence.
Exacerbations were measured by self-reported questionnaire after 6 and 12 months. Patients had to indicate whether they experienced an exacerbation (yes/no) during the past 6 or 12 months. During PR, patients learned to identify exacerbations and how to react appropriately.
Patient-reported reasons for nonadherence were also measured in the self-reported questionnaire that was filled in after 6 and 12 months. It contained 2 questions referring to hospital admittance (necessity and frequency of hospitalizations) and 5 questions referring to satisfaction with, and conditions of, the maintenance program, such as training facilities, group or individual training, satisfaction with illness-specific knowledge, instructions and support given by the physiotherapist, and about their ideal maintenance program.
The descriptive statistics of the patient characteristics and predictor variables were calculated. Logistic regression analysis using forward selection was performed to test the ability of the predictor variables to predict adherence (adherent = 1, nonadherent = 0) in patients with COPD. The model assumption of a linear relationship between predictors and the primary outcome variable was checked, and Pearson correlations were calculated to study the collinearity of predictors included in the final prediction model. The Hosmer and Lemeshow Test was used to study model fit. All statistical analyses were performed with SPSS 18.0 (SPSS, Inc, Chicago, IL).
In total, 70 patients with COPD were included (age, 61.3 years [SD = 10.2]; 45.7% men; 50% GOLD IV), of whom, 3 were lost because of nonresponse and 7 patients died during the study period. The remaining 60 patients were on average 61.3 (SD = 10.3) years old, and 46.7% were men. Of the included subjects, 48.3% had COPD, GOLD class IV. No systematic differences were observed between the original group of 70 patients and the remaining sample.
After 6 months, 44 of the 60 patients (73.3%) were still following the maintenance program. Over the next 6 months, another 6 patients dropped out, so that in total, 38 (63.3%) patients followed the maintenance program after 1 year and 22 (36.7%) patients had stopped. The adherent and nonadherent groups were similar in demographic variables, such as age, gender, BMI, and GOLD class status (Table 1). However, the nonadherent group was lower educated than the adherent group. Also, forced expiratory volume in 1 second, % predicted, was significantly higher in the adherent group than in the nonadherent group. The average duration of PR was 9 to 12 weeks, 3 days a week, with 2 units of exercise training a day, in addition to other educational and psychological elements of PR. The descriptive statistics of the predictor variables to be included in the logistic regression analyses are presented in Table 2.
Logistic Regression Model
The forward selection procedure revealed that FEV1 was the best predictor of adherence (P = .025). Therefore, this variable was included in the prediction model in step 1. Subsequently, TLC was the most significant predictor with P = .059 and, thus, included in step 2. In step 3, the HADS depression score was included (P = .046), which, however, resulted in a nonsignificant effect on TLC. To study whether it was justified to remove TLC from the model, a likelihood ratio test was performed. This revealed a significant decrease (χ2= 7.48, df = 1, P = .0062) in model fit after removing TLC, which indicated that TLC should be kept in the model. Finally, in step 4, the duration of rehabilitation was found a significant predictor of adherence. The Hosmer and Lemeshow Test indicated a good overall model fit (χ2= 13.12, df = 8, P = .11) of the prediction model with 4 predictors of adherence (Table 3).
Table 3 shows the final model: with 1 liter increase in FEV1, the odds for adherence is 6.8 (95% CI: 1.33-34.52) times higher (P = .021). The odds for adherence decrease by 0.77 (95% CI: 0.62-0.97) with a 1 unit increase in the HADS depression score (P = .025). Finally, adherence increases with an increase of 1 week of duration of rehabilitation by 1.25 (95% CI: 1.04-1.50, P = .018). The 4 predictors appeared to be independent predictors for adherence, as the check for multicollinearity revealed no significant correlations.
Exacerbations occurred frequently in both groups: 60% of patients reported having had 1 or more exacerbations, but in the nonadherent group, an exacerbation was the most reported reason for dropout. Patient satisfaction with the maintenance program was moderate (n = 22) to very high (n = 27). Most patients preferred training in a group (n = 40) to individual training (n = 10). Illness-specific knowledge (ie, concerning over- and underweight, medical problems in COPD such as exacerbations, and specific training modalities) of the physiotherapist was mentioned as the most important aspect of the maintenance program.
This study shows that a large portion of patients with COPD were adherent to a maintenance exercise program after completing the PR program. At 6 months, 73.3% was still adherent to the program, and at 12 months, the number was 63.3%. Satisfaction with the maintenance program was reasonable to very good, and patients preferred therapy in a group to individual training. The recognition of problems and being able to discuss these with other patients with COPD were reported to be important reasons for continuing the maintenance program. Knowledge of COPD characteristic problems by the physiotherapist was also an important factor for good aftercare.
The most frequently patient-reported reason for dropout was exacerbations. The logistic model showed that especially (1) worse disease (lower FEV1), (2) more depressive symptoms, and (3) shorter duration of the rehabilitation program predicted drop-out from our maintenance exercise program. Health-related quality of life, anxiety, self-efficacy, exacerbations, and illness perceptions were found not to be predictive for adherence, probably due in part to shared variance with other variables, for example, FEV1.
With respect to the first predictor, previous studies have reported that disease severity and internal (psychological and physical factors) and external (environmental and social factors) barriers have a negative effect on adherence to physical activity and maintenance programs of patients with COPD.22,47 Patients with more severe COPD were less adherent to an exercise program because of greater impairment and disability and larger susceptibility to exacerbations.28,33 Patients in our study reported that exacerbations were an important reason for dropout. Not finding exacerbations as a predictor may be because of the fact that exacerbations were measured by self-report. Patients indicated whether they experienced an exacerbation in the past 6 or 12 months. Although patients had learned to recognize exacerbations as a result of PR, confirmation by a specialist was lacking and severity of exacerbations was not tracked. This might have resulted in biased observations.
The second predictor, “having depressive symptoms,” has been linked to lower adherence and results in lower health status and greater functional impairments.23,48 Depressive symptoms are also an independent prognostic factor of mortality in stable patients with COPD.49 Depression has been reported in 20% to 60% of patients with COPD.50 A review of longitudinal studies on the relationship between depression and physical activity has indicated that depression at baseline was significantly associated with a decline in physical activity and having a sedentary lifestyle.51 This may explain why patients with depressive symptoms are less inclined to adhere to a maintenance exercise program. Several explanations are mentioned, such as the association of depression with decreased interest, motivation, and energy. Also, hyperactivity of the hypothalamic-pituitary-adrenal axis seems to be associated with depression and sedentary behavior. Furthermore, it has been suggested that the relationship between depression and physical activity is likely to be bidirectional, as depression is known to have a negative effect on physical activity, but conversely, regular exercise significantly decreases the risk for depression in adults.52 Stimulating exercise and treating patients with depressive symptoms may break down the potential vicious circle and have a positive influence on adherence.
The third predictor, “length of rehabilitation,” was also found to be a significant predictor for adherence but is rather difficult to explain. Patients with a slower response to rehabilitation were treated for a longer period and may therefore have had more time to develop a behavior change. Although the duration of PR was set at 9 to 12 weeks, this was sometimes extended on the basis of the clinical opinion of the multidisciplinary team. There is some evidence in literature for the positive influence of longer duration of rehabilitation on exercise performance and HRQOL.53 Patients with COPD who were trained for 6 months experienced improvements in walking distance and HRQOL that were maintained for 18 months,11 whereas in another study, patients were trained for 6 to 8 weeks, with no long-term benefits.8
Several studies, focusing on the elderly in general28,54 and patients with COPD in particular28,55 demonstrated that self-efficacy and expected benefits from regular exercise were predictors of adherence to maintenance of physical activity. This conflicts with our results. An explanation for not finding these and other predictors might be the relative small sample. Another limitation was that we did not explicitly ask nonadherent patients whether the reason for nonadherence was participation in another physical activity. Choosing another, perhaps more suitable type of physical activity may indicate appropriate self-management. In the self-reported questionnaire, only 1 patient mentioned participation in another physical activity as reason for nonadherence. Furthermore, given that our adherence percentage of 63.3% is already higher than the general exercise adherence of 50%, we expect this drawback was a minor influence.
Another potential drawback could be the fact that patients went to different settings that might have confounded the adherence outcome. Evaluating the effect of a standardized maintenance program would be interesting. However, the current program was already standardized to some extent, as all physiotherapists worked according to the COPD guidelines, obtained written information about the course of PR of each patient, and recommendations for continuing exercise training were provided. Finally, it would have been interesting to study the effects of a maintenance program by comparing the changes in ISWT scores between the adherent and nonadherent group 12 months after PR.
Adherence to a maintenance exercise program, after PR, is quite reasonable for patients with COPD. Nonetheless, about one-third of patients dropped out during the first year. Experiencing exacerbations was the most reported reason for dropout. Greater health impairments, that is, poorer lung function and more symptoms of depression, appeared to be predictive for dropout. Taking these factors into account may help in early identification of possible dropouts. Further research should indicate whether individually tailored guidance directed at these predictors is the best way to enhance adherence to exercise programs.
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adherence; maintenance program; pulmonary rehabilitation