Introduction
Chronic obstructive pulmonary disease (COPD) is a chronic, multi-factorial systemic disease worldwide with significant morbidity, which incurs heavy utilization of healthcare resources [
1]. As a nonreversible disease, primary treatment goals of COPD aim to relieve symptoms and limit exacerbations while maximising functional ability and wellbeing [
2]. However, fluctuating symptoms, various disabilities, and varying levels of well-being often complicates medical care of COPD [
3]. In the last decade, the integrated care model (IDM), a multi-disciplinary and multi-component programme, has been proposed as an optimal strategy to address the challenges in COPD management [
3‐
5].
A recent meta-analysis of 52 randomized trials demonstrated that IDM programme with a follow-up period at least 3 months hold the promise to improve disease-specific quality of life (QoL) and exercise capacity and demonstrated reduction in hospital admissions and hospital days per person [
3]. In real-world evidence, a nationwide COPD IDM program in Taiwan exerted a positive net effect on reducing the likelihood of COPD exacerbation, such as COPD-related ED visits and hospitalizations [
6]. An improved health status was also found in patients with COPD who received care according to the IDM program, namely COPDnet [
7]. While RCTs and real-world studies have shown the efficacy and effectiveness of IDM programs on COPD management, the appropriate intervention duration is still unknown.
Recently, appropriate intervention duration of IDM program have been recommended to be a measure for assessing the cost-effectiveness on IDM program [
8]. However, to the best of our knowledge, there are no study regarding the impact of duration of IDM program on COPD-related outcomes. Previous meta-analysis study revealed that the beneficial effects of COPD IDM program on health-related quality of life (SGRQ: St. George’s Respiratory Questionnaire) are statistically significant in the short term (up to 6 months) and in the medium term (6 to 15 months). IDM probably results in a reduction in emergency department (ED) visits and a fewer hospital days per person admitted with median follow-up 12 months [
3]. However, there is no conclusion about the more effective intervention duration for COPD IDM program. In the Netherlands, a 2 year cluster RCT in 40 general practices found that IDM program for patients with COPD in primary care increased costs without improvement in health outcomes [
9]. Consequently, the inappropriate intervention duration of IDM may not improve quality of care for patients with COPD and increase the financial burden on the health care system.
The aim of this study is to evaluate the impact of the intervention duration of the COPD IDM program on COPD-related outcomes in real-world settings. We first investigate influence of intervention duration on the change in COPD-specific QoL using CAT score as an indicator. In addition, we further assess the association between intervention duration and CAT MCID improvement. We further analyzed the factors associated with CAT MCID improvement, and risk of subsequent COPD exacerbation between patients with or without COPD-specific QoL.
Discussion
Our study is the first to demonstrates the association between the intervention duration of COPD IDM program and COPD-related outcomes in real-world setting. Our finding indicates that likelihood of achieving CAT MCID improvement is lower at 3- and 6 month compared to 9 month and a modest increase likelihood of improvement at 12- month compared with 9 month. CAT MCID improvement was most associated with baseline CAT scores. From 3 to 12 month follow-up results showed continued improvement over time in COPD-specific health status, particularly in patients with baseline CAT score of ≥ 10. In addition, patients with CAT MCID improvement had lower risk of subsequent COPD exacerbation.
The meta-analysis summarized the literatures analyzing 52 trials involving 21,086 participants from 19 countries in a variety of health care settings with the follow-up periods ranged between 3 and 48 months, concluding that IDM probably improves health-related QoL in medium-term follow-up (> 6 to 15 months) [
3]. In our study, we found that IDM interventions continuously improves COPD-specific QoL over 1 year and patients were likely to achieve MCID improvement in CAT score after 9 month- follow-up. Compared to previous meta-analysis, our real-world study provides direct evidence that the amount of time between baseline and follow-up influenced the change of QoL at follow-up, which supports that IDM intervention duration longer than 6 month significantly ameliorate COPD-specific QoL. This study measured QoL using the CAT score since it is a concise and validated questionnaire that can easily be implemented instead of the St. George’s Respiratory Questionnaire (SGRQ) used in Poots' meta-analysis. Although it is difficult to directly compare the magnitude of the effect between our study and those in the Poots’ meta-analysis study due to the use of different QoL tools. The St. George’s Respiratory Questionnaire (SGRQ) and the CAT score perform similarly have been validated by previous studies [
13,
14]. Conservatively, the improvements in QoL measured in our study are consistent with those reported in previous research on COPD IDM intervention.
In Poots meta-analysis study, the mean improvement in QoL measured by the SGRQ was 3.89 which do not achieve MCID for the SGRQ at medium-term follow-up. Similar to our study, the mean improvement in total CAT score also do not achieve CAT MCID threshold (≥ 2 points reduction) during 1 year study period. Previously, Ferrone et al. study evaluated the IDM intervention in a high risk, frequent exacerbation population with a poor baseline QoL (mean CAT score of all subjects was 21). Result from the study demonstrated that QoL improved in the IDM cohort with a CAT score of 22.6 at baseline and 14.8 at 12 months, whereas The CAT score increased from 19.3 to 22.0 in the usual care arm [
15]. The authors confirmed that an IDM intervention substantially improved QoL in a high-risk primary care population. Therefore, we suggest that IDM intervention may have more beneficial effect on patients with poor conditions at baseline than those are not. Patients with CAT score of ≥ 10 were indicating medium-to-very high impact of COPD on the patient’s life has been reported [
16,
17]. Our result found that patients with CAT score ≥ 10 were more likely to achieve CAT MCID improvement. Moreover, in CAT score ≥ 10 group, the mean changed from baseline in CAT score at all 4 time points with 1 year were greater than − 2 point (ranged from − 2.05 to − 3.25 point), which achieved MCID threshold. These findings support that patients with poor baseline conditions, particularly CAT score ≥ 10 at baseline, are the potential beneficiary group of COPD IDM program by improving COPD-specific QoL for reducing the impact of COPD on the patient’s life.
Besides CAT score at baseline, the other factors associated with MCID improvement in CAT score included frequent exacerbation (2 episodes/year), wheezing, and GOLD B and D. In previous study, the integrated care program had a significant beneficial impact on health status in patient with frequent exacerbator, with a reduction in CAT score from 19 to 15 after 1 year of follow-up [
18]. In addition, patients enrolled in the IDM program classified as GOLD B and D at baseline had more improvement in CAT scores than GOLD A and C after 1 year follow-up [
19]. According to these evidence, at baseline condition, patients with CAT score ≥ 10, frequent exacerbation, or GOLD B and D are the potential candidate who may had more benefit from IDM intervention.
Patients with CAT score of ≥ 10 at baseline had higher exacerbation risk compared to those with CAT < 10 at baseline has been identified in previous study [
20]. Similar to our finding, patients with CAT score of ≥ 10 (both patient with or without CAT MCID improvement) had higher risk of COPD exacerbation event, including ED visit and hospitalization. However, patients (with CAT score of < 10 or ≥ 10) who achieve CAT MCID improvement significantly had lower risk of subsequent COPD exacerbation event compared to those did not. In previous study, the group with improved CAT score (patients who exhibited a decrease of 2 points or more) had significantly fewer moderate-to-severe exacerbations than the those without improvement during the short-term (approximately 6 months) follow-up after bronchodilator therapy [
21], which is similar with our result. Moreover, patients with stable or improved health status during 1 year follow-up had a lower likelihood of exacerbation also has been reported [
22]. These findings support that patients who participated in IDM program with MCID improvement in CAT score are likely to reduce the risk of subsequent COPD exacerbation events. In addition, the change in CAT score provides a simple estimate of exacerbation risk during IDM intervention, providing useful information for maintaining patient stability.
There are some limitations to this study. First, the study findings may not be generalizable to other countries or populations due to the unique health care system and COPD P4P model in Taiwan. Second, since adherence evaluations are based on claims data, we assumed that filled prescriptions are proxies for medication adherence. It must be noted, however, that a filled prescription is not proof that the patient took it. Due to our assumption that every filled prescription was fully taken, our estimated medication adherence rates overestimate real medication adherence. Third, only 1 year follow-up was included in our study, so assessing the P4P program’s effect on mortality was difficult. Forth, the implementation of pulmonary rehabilitation program depends on the physicians’ judgement and patient's clinical condition. Moreover, record of home-based pulmonary rehabilitation is unavailable in NHIRD. Therefore, rate of participating pulmonary rehabilitation may underestimate.
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