What is COPD and comorbidity?
COPD is a common condition caused mainly by smoking and can lead to long-term breathing problems. Symptoms include shortness of breath, and cough with sputum production due to airways and lung damage. People with COPD may have one or more other long-term conditions (comorbidities) such as heart disease, hypertension, diabetes, asthma and lung cancer which can lead to poor health. People living with two or more comorbidities can also be known as living with multimorbidity.
Why did we do this review?
Because many people with COPD live with multimorbidity, naturally people in clinical trials will have multimorbidities. However, the results of those trials are usually not reported broken down by multimorbidity. People with comorbidities may need to adapt interventions to take account of their comorbidity — for example taking exercise in water instead of on land so that their bodies are better supported. Historically, Cochrane Airways Reviews have not taken into account people's comorbidities, and this review is a first step to addressing this. We decided to complete a review that centres on people with COPD and comorbidities following a meeting with our COPD patient group, who highlighted concerns over comorbidities. After some deliberation, we decided to include the following two sorts of trials.
1. Any single intervention for COPD delivered to people with COPD adapted to or targeting their comorbidity compared to routine care or any other intervention.
2. Any intervention aimed at changing the management of people with COPD and comorbidities, which could be simple (e.g. scheduling COPD and heart clinics on the same day) or more complex (e.g. developing a new care package for management of people with COPD across a local health service), compared to routine care.
We wanted to know which treatments improve quality of life and reduce exacerbations for people living with COPD and one or more comorbidities.
We also wanted to find out about how people with COPD, carers and health professionals felt about those treatments.
What information did we find?
We carried out a search for studies in January 2021. We found seven eligible randomised controlled trials (RCTs) including 1197 people, and one qualitative study which was part of one of the randomised trials and provided information about people's opinions and experiences of using telehealth equipment. People included in the trials were aged between 64 and 72 years, and their COPD severity ranged from mild to very severe. The trials either included people with COPD and a specific comorbidity such as cardiovascular disease or lung cancer, or they included people with COPD and one or more other conditions of any sort.
Results and conclusions
There is not enough evidence on people with COPD and other comorbidities to draw firm conclusions about interventions aimed at COPD that are adapted for the comorbidity. The available evidence indicated the following:
- Quality of life as measured by the St George's Respiratory Questionnaire (SGRQ) total score may improve with tailored pulmonary rehabilitation compared to usual care (note that there is a strong evidence base for pulmonary rehabilitation in people with COPD).
- Pulmonary rehabilitation is likely to improve quality of life as measured by the COPD assessment test (CAT) scores compared with usual care at 52 weeks and with a multicomponent telehealth intervention.
- Evidence is uncertain about the effects of pharmacotherapy optimisation or telemonitoring interventions on CAT improvement compared with usual care.
- There may be little to no difference in the number of people experiencing exacerbations, or mean exacerbations with case management compared with usual care.
- For secondary outcomes, the distance walked by participants in six minutes may improve with pulmonary rehabilitation, water-based exercise or multicomponent interventions. A multicomponent intervention may result in fewer people being admitted to hospital, although there may be little to no difference in a telemonitoring intervention.
- There may be little to no difference between intervention and usual care for deaths across several studies.
- One study compared water-based exercise with land-based exercise. We found no evidence for quality of life or exacerbations. There may be little to no difference between water- and land-based exercise on the distance walked by participants in six minutes.
- One qualitative study explored perceptions and experiences of people with COPD and long-term conditions, and of researchers and health professionals who were involved in an RCT of telemonitoring equipment. Several themes were identified, including health status, beliefs and concerns, reliability of equipment, self-efficacy, perceived ease of use, factors affecting usefulness and perceived usefulness, attitudes and intention, self-management and changes in healthcare use.
Larger studies with more people with COPD and comorbidities could help to find out if targeted approaches can improve health.
Certainty of the information
Overall there were very few studies and most studies were small. This means the results are based on a small amount of information. Trials with different interventions and different or more people may give a different result.
Owing to a paucity of eligible trials, as well as diversity in the intervention type, comorbidities and the outcome measures reported, we were unable to provide a robust synthesis of data. Pulmonary rehabilitation or multicomponent interventions may improve quality of life and functional status (6MWD), but the evidence is too limited to draw a robust conclusion. The key take-home message from this review is the lack of data from RCTs on treatments for people living with COPD and comorbidities.
Given the variation in number and type of comorbidity(s) an individual may have, and severity of COPD, larger studies reporting individual patient data are required to determine these effects.
Chronic obstructive pulmonary disease (COPD) is a chronic respiratory condition characterised by shortness of breath, cough and recurrent exacerbations. People with COPD often live with one or more co-existing long-term health conditions (comorbidities). People with more severe COPD often have a higher number of comorbidities, putting them at greater risk of morbidity and mortality.
To assess the effectiveness of any single intervention for COPD adapted or tailored to their comorbidity(s) compared to any other intervention for people with COPD and one or more common comorbidities (quantitative data, RCTs) in terms of the following outcomes: Quality of life, exacerbations, functional status, all-cause and respiratory-related hospital admissions, mortality, pain, and depression and anxiety.
To assess the effectiveness of an adapted or tailored single COPD intervention (simple or complex) that is aimed at changing the management of people with COPD and one or more common comorbidities (quantitative data, RCTs) compared to usual care in terms of the following outcomes: Quality of life, exacerbations, functional status, all-cause and respiratory-related hospital admissions, mortality, pain, and depression and anxiety.
To identify emerging themes that describe the views and experiences of patients, carers and healthcare professionals when receiving or providing care to manage multimorbidities (qualitative data).
We searched multiple databases including the Cochrane Airways Trials Register, CENTRAL, MEDLINE, Embase, and CINAHL, to identify relevant randomised and qualitative studies. We also searched trial registries and conducted citation searches. The latest search was conducted in January 2021.
Eligible randomised controlled trials (RCTs) compared a) any single intervention for COPD adapted or tailored to their comorbidity(s) compared to any other intervention, or b) any adapted or tailored single COPD intervention (simple or complex) that is aimed at changing the management of people with COPD and one or more comorbidities, compared to usual care. We included qualitative studies or mixed-methods studies to identify themes.
We used standard Cochrane methods for analysis of the RCTs. We used Cochrane's risk of bias tool for the RCTs and the CASP checklist for the qualitative studies. We planned to use the Mixed Methods Appraisal tool (MMAT) to assess the risk of bias in mixed-methods studies, but we found none. We used GRADE and CERQual to assess the quality of the quantitative and qualitative evidence respectively. The primary outcome measures for this review were quality of life and exacerbations.
Quantitative studies
We included seven studies (1197 participants) in the quantitative analyses, with interventions including telemonitoring, pulmonary rehabilitation, treatment optimisation, water-based exercise training and case management. Interventions were either compared with usual care or with an active comparator (such as land-based exercise training). Duration of trials ranged from 4 to 52 weeks. Mean age of participants ranged from 64 to 72 years and COPD severity ranged from mild to very severe. Trials included either people with COPD and a specific comorbidity (including cardiovascular disease, metabolic syndrome, lung cancer, head or neck cancer, and musculoskeletal conditions), or with one or more comorbidities of any type.
Overall, we judged the evidence presented to be of moderate to very low certainty (GRADE), mainly due to the methodological quality of included trials and imprecision of effect estimates.
Intervention versus usual care
Quality of life as measured by the St George's Respiratory Questionnaire (SGRQ) total score may improve with tailored pulmonary rehabilitation compared to usual care at 52 weeks (mean difference (MD) −10.85, 95% confidence interval (CI) −12.66 to −9.04; 1 study, 70 participants; low-certainty evidence). Tailored pulmonary rehabilitation is likely to improve COPD assessment test (CAT) scores compared with usual care at 52 weeks (MD −8.02, 95% CI −9.44 to −6.60; 1 study, 70 participants, moderate-certainty evidence) and with a multicomponent telehealth intervention at 52 weeks (MD −6.90, 95% CI −9.56 to −4.24; moderate-certainty evidence). Evidence is uncertain about effects of pharmacotherapy optimisation or telemonitoring interventions on CAT improvement compared with usual care.
There may be little to no difference in the number of people experiencing exacerbations, or mean exacerbations with case management compared with usual care (OR 1.09, 95% CI 0.75 to 1.57; 1 study, 470 participants; very low-certainty evidence).
For secondary outcomes, six-minute walk distance (6MWD) may improve with pulmonary rehabilitation, water-based exercise or multicomponent interventions at 38 to 52 weeks (low-certainty evidence). A multicomponent intervention may result in fewer people being admitted to hospital at 17 weeks, although there may be little to no difference in a telemonitoring intervention. There may be little to no difference between intervention and usual care for mortality.
Intervention versus active comparator
We included one study comparing water-based and land-based exercise (30 participants). We found no evidence for quality of life or exacerbations.
There may be little to no difference between water- and land-based exercise for 6MWD (MD 5 metres, 95% CI −22 to 32; 38 participants; very low-certainty evidence).
Qualitative studies
One nested qualitative study (21 participants) explored perceptions and experiences of people with COPD and long-term conditions, and of researchers and health professionals who were involved in an RCT of telemonitoring equipment.
Several themes were identified, including health status, beliefs and concerns, reliability of equipment, self-efficacy, perceived ease of use, factors affecting usefulness and perceived usefulness, attitudes and intention, self-management and changes in healthcare use. We judged the qualitative evidence presented as of very low certainty overall.