Factors associated with poor long-term adherence after completing a pulmonary rehabilitation programme in patients with chronic obstructive pulmonary disease

1 Introduction

COPD is a multisystem disease with cardiovascular, metabolic and musculoskeletal manifestations that provokes physical deconditioning and loss of muscle strength at long-term progression [1–3]. Likewise, this disease is characterized by the presence of COPD exacerbations that impact on the dyspnoea, the quality of life, impair lung function, increase hospital admissions and are associated with higher mortality [3–5].

Pulmonary rehabilitation (PR) consists of a comprehensive intervention comprised of various therapies tailored to the patient’s needs and includes muscle training, education and changes in lifestyle habits [1–3]. PR is a non-pharmacological therapy for treating COPD as it improves dyspnoea, exercise capacity, anxiety, depression and other comorbidities [2–4].

Although COPD management guidelines recommend PR, the intervention is not adequately offered or provided to all patients [1–8]. In addition, an estimated 10% –32% of patients with COPD included in PR programmes (PRPs) do not properly adhere to them or do not experience clinical improvement [9–11]. A number of studies have reported that the quality of life, degree of dyspnoea and lung function affect short-term adherence to PRPs [11–14]. Furthermore, the reduced physical activity observed in COPD patients may impact on their behavior leading to less motivation, fear to injury and the onset of symptomatology compatible with depression or anxiety; all of them can also impact on the adherence to PRP [15, 16].

However, these studies are heterogeneous and often fail to provide a clear and concise definition of “adherence” and of the characteristics that affect it [11–14]. Moreover, other studies have shown that the absence of clinical improvement and the difficulty in attending training sessions are important aspects to consider when discussing PRP non-adherence [12–14]. Regarding to that, it has been recommended some alternatives like technology support, such as commercial activity monitor or motion capture devices, because they could improve the patients’ adherence to the PRPs [17, 18].

Likewise, it is important to consider that most previous studies have focused on the analysis of the short-term adherence to PRPs and not on the long-term monitoring of the recommendations provided by these programmes [13, 19]; there have been mixed results regarding the repercussion of COPD exacerbations on PRP adherence [14, 19]. Hence, long-term non-adherence to PRP in COPD would counter the beneficial health effects provided by this intervention.

There is therefore conflicting evidence regarding the conditions that lead to the long-term abandonment of PRPs. The aim of our study was therefore to analyse the features of patients with COPD that contribute to long-term non-adherence to PRPs after adequately completing the programmes.

2 Materials and methods

2.5 Intervention

In our unit, patients undergo a face-to-face PRP consisting of 3 training sessions per week, which involve aerobic training and skeletal muscle endurance exercises, physiotherapy and COPD education programmes (2 disease information sessions). Thus, participants included in a PRP attend 3 medical visits: at baseline (before starting the PRP); after completing the PRP (8 weeks after the baseline assessment and after attending at least 17 training sessions); and at 32 weeks after beginning the PRP (Fig. 1).

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Fig. 1

Study design. ^*Participants included in a PRP attend 3 medical visits: at baseline (visit at 0 week); after completing the PRP (visit at 8 weeks after the baseline assessment); and at 32 weeks after the baseline assessment. PRP: Pulmonary Rehabilitation Programme; *Patient is informed about the structure of the PRP.

3 Results

For patients with COPD, PRPs have a positive impact on the treatment of the disease [12–14, 19–25]. Our results therefore confirm that PR improves dyspnoea, quality of life, daily physical activity and the emotional state of patients. Nevertheless, our findings also confirm that a high percentage of patients drop out of these programmes in the long term. In addition, severe COPD exacerbations might be associated with this higher rate of abandonment.

This study shows the effect of COPD exacerbations on PRP adherence. The number of COPD exacerbations in our patients was lower than that reported in other studies. This is probably due to the fact that we included a larger percentage of patients with greater COPD severity than other studies [12–14, 19]. In addition, we evaluated patients three times during the follow-up (baseline, eight weeks and 32 weeks) by both pneumologists and rehabilitation physicians that work jointly in our respiratory rehabilitation unit. We observed that severe COPD exacerbations that occurred one year before the onset of this treatment behaved as a risk factor for long-term PRP non-adherence. However, Almadana-Pacheco et al. [14], Braeken, et al. [28] and Steele, et al. [29] did not detect this association in their studies. This conflicting finding might be explained by the differences observed in the lung function between the compared groups (PRP drop-out vs. non-PRP drop-out). Hence, in contrast to the study by Almadana-Pacheco et al. [14], in which the participants who abandoned PRPs had poorer FEV₁, our series showed no statistically significant differences in FEV₁ between the two groups. Unlike Braeken, et al. [28], we observed no positive impact of PRP on the anxiety state (HADS questionnaire) or on the COPD health-related quality of life (CAT questionnaire), which could explain the tendency of not continuing the PRP in the long-term. We can therefore tentatively suggest that long-term non-adherence to PRPs associated with severe COPD exacerbations could be influenced by a poorer COPD-related quality of life and by a higher anxiety state. It has been demonstrated that COPD exacerbations result in a worsening of dyspnoea in the moderate-long term. Almadana-Pacheco, et al. [14] found that dyspnoea was associated with a higher rate of PRP abandonment, and we observed a higher degree of dyspnoea in the group that dropped out of the PRP. New hypotheses, are therefore needed to investigate why severe COPD exacerbations affect the long-term adherence of PRP and thereby reduce PRP abandonment.

As noted above, we detected a higher degree of dyspnoea in the group with long-term PRP non-adherence, which is probably related to the occurrence of COPD exacerbations, whose negative impact on quality of life, lung function and degree of dyspnoea has been shown in various studies [5,20, 5,20]. Nevertheless, we observed no significant differences between the patients who dropped out and those who did not in terms of quality of life and lung function, which is consistent with the results of previous studies [13–19, 29]. Future studies with larger numbers of participants would therefore be required to clarify the role of quality of life and lung function in the long-term abandonment of PRP.

The drop-out rate reported in this article is 45%, which is somewhat higher than the 9% –32% rate reported in other published studies [30,31, 30,31], a difference that might be due to the fact that 31% of our patients experienced at least one severe COPD exacerbation in the past year, a higher rate than in other reports [27–34]. Nevertheless, our study focused on the long-term abandonment of PRP in a defined patient group who did not drop out of PRP in the short-term (attended more than 70% of the PRP sessions). The study therefore assessed the long-term abandonment of patients, defined in other studies as “fulfillers”, which might explain this higher drop-out rate when comparing our results with those of other studies [10].

We employed endpoints that have been accepted in other studies to assess the positive effects of PR. We therefore evaluated the degree of dyspnoea, quality of life, physical activity and 6MWT. Nonetheless, we did not consider the patient activation measure, which could have been useful in our study. Our observations showed that, after an 8-week PRP, the positive effects of PR were consistent with the results reported in other articles [1–3, 29]. We also observed a positive impact on the degree of dyspnoea, in contrast to other studies that detected no such effect on this major symptom, which is a frequent complaint in subjects with COPD [23]. There was also a notable improvement in the quality of life, the level of anxiety and in the distance walked in the 6MWT; however, the improvement did not reach statistical significance (Table 2).

This study has a number of limitations. First, the sample size was relatively small, which could have affected the discovery of more factors associated with the abandonment of long-term PR. Nonetheless, other studies used similar or even smaller sample sizes [12,14, 12,14]. Second, there were problems resulting from the retrospective analysis in terms of patient selection. Another issue were the data obtained in relation to exposure, given that the exposure to the PRP and its effects had already occurred when the protocol began. Nevertheless, we were careful in selecting the included population, unlike other studies that also included patients who attended less than half of the scheduled PRP sessions, with the potential selection bias this might induce [12–14, 19]. Our population was younger, had more comorbidities and a greater COPD severity than those of other studies [13–15, 23]. Last, with respect to the recorded data, we did not analyse the detailed patient activity, lifestyle habits and socioeconomic variables. However, we attempted to include most of the factors already analysed in other studies and even characteristics that had not been previously evaluated, such as each of the comorbidities that constitute the Charlson index, specific therapies for treating COPD and the GOLD classification according to the latest guidelines [12–14, 20]. Furthermore, we did not measure the smoking history at 32 weeks after the onset of PRP, which might be an interesting aspect to evaluate in both groups after completing the PRP.

5 Conclusion

This study suggests that severe COPD exacerbations affect the long-term abandonment of PRP. These results require more research, with larger sample sizes and more than 1 medical centre, with the aim of standardising the programmes and the criteria for patient inclusion. We therefore need to continue this line of research with future protocols that help to determine more precisely the factors involved in PRP abandonment, thereby modifying programmes to ensure a greater impact for a larger number of patients with COPD.