Evidence
This page contains a snapshot of featured content which highlights evidence addressing key clinical questions including areas of uncertainty. Please see the main topic reference list for details of all sources underpinning this topic.
BMJ Best Practice evidence tables
Evidence tables provide easily navigated layers of evidence in the context of specific clinical questions, using GRADE and a BMJ Best Practice Effectiveness rating. Follow the links at the bottom of the table, which go to the related evidence score in the main topic text, providing additional context for the clinical question. Find out more about our evidence tables.
This table is a summary of the analysis reported in a Cochrane Clinical Answer that focuses on the above important clinical question.
Confidence in the evidence is moderate or low to moderate where GRADE has been performed and the intervention may be more effective/beneficial than the comparison for key outcomes.
Population: People with acute hypercapnic respiratory failure due to chronic obstructive pulmonary disease exacerbation
Intervention: NIV plus usual care
Comparison: Usual care alone (combinations of pharmacological therapies)
| Outcome | Effectiveness (BMJ rating)? | Confidence in evidence (GRADE)? |
|---|---|---|
Mortality (where reported, duration of follow‐up to intensive care unit [ICU] or hospital discharge) | Favours intervention | Moderate |
Need for endotracheal intubation (where reported, duration of follow‐up 3 days to 30 days, ICU discharge, or hospital discharge) | Favours intervention | Moderate |
Symptom scores (1 hour to 3 days) | No statistically significant difference | GRADE assessment not performed for this outcome |
Duration of ICU stay | No statistically significant difference | GRADE assessment not performed for this outcome |
Duration of hospital stay | Favours intervention | Moderate |
Treatment intolerance | Favours comparison | GRADE assessment not performed for this outcome |
Partial pressure of carbon dioxide (PaCO2; 1 hour post‐intervention) | No statistically significant difference | GRADE assessment not performed for this outcome |
Partial pressure of oxygen (PaO2; 1 hour post‐intervention) | Favours intervention | GRADE assessment not performed for this outcome |
Complications of treatment: NIV-related | See note ᵃ | GRADE assessment not performed for this outcome |
Complications of treatment: Non-NIV-related | Occurs more commonly with usual care alone compared with NIV plus usual care (favours intervention) | GRADE assessment not performed for this outcome |
Note ᵃ 30% of people in the NIV plus usual care group had complications specifically related to NIV (not experienced in the usual care alone groups). See Cochrane Clinical Answer (CCA) for more details.
This evidence table is related to the following section/s:
This table is a summary of the analysis reported in a Cochrane Clinical Answer that focuses on the above important clinical question.
Confidence in the evidence is moderate or low to moderate where GRADE has been performed and there may be no difference in effectiveness between the intervention and comparison for key outcomes.
Population: Selected adults presenting at emergency rooms with acute exacerbation of COPD ᵃ
Intervention: Hospital-at-home (regular home visits by trained respiratory nurse supported by hospital team)
Comparison: Standard inpatient care
| Outcome | Effectiveness (BMJ rating)? | Confidence in evidence (GRADE)? |
|---|---|---|
Hospital re-admission (follow up: 1–6 months) | Favours intervention | Moderate |
Mortality (follow up: 2–6 months) | No statistically significant difference | Moderate |
FEV1 | No statistically significant difference | Low |
FVC | No statistically significant difference | GRADE assessment not performed for this outcome |
Quality of life (follow up: at discharge) | See note ᵇ | Very Low |
Satisfaction with care (follow up: 0–2 weeks after discharge; subgroup: patient satisfaction) | No statistically significant difference | Low |
Satisfaction with care (follow up: 0–2 weeks after discharge; subgroup: carer satisfaction] | No statistically significant difference | Very Low |
Speed of exacerbation recovery, recurrent exacerbations | - | None of the studies identified by the review assessed these outcomes |
Note The Cochrane Clinical Answer (CCA) noted that patient characteristics varied across reviewed studies in terms of lung function and reasons for trial exclusion, affecting the generalisability of results. It also noted that the co-interventions given to participants varied across studies. The Cochrane review which underpins this CCA noted that while the review showed that treatment with a hospital-at-home scheme is safe, acceptable, and as effective as inpatient care, the majority of patients will still continue to require hospital care for their exacerbation. They also highlighted that more studies are required to evaluate the cost-effectiveness of hospital-at-home schemes. ᵃ The CCA noted that trials reported variable respiratory exclusion criteria (e.g., respiratory failure, pneumonia, pneumothorax, lung cancer, chest X‐ray changes, pulmonary embolism, hypoxia) and also that patients with acute/unstable co‐morbidities, reduced level of consciousness, and/or confusion were excluded by some trials. ᵇ Results reported narratively. Three RCTs (332 participants) reported quality of life using the St George’s Respiratory Questionnaire. Results could not be combined since one study reported percentage improvement while the other two reported standard deviations. The latter showed no statistically significant difference between treatment groups.
This evidence table is related to the following section/s:
This table is a summary of the analysis reported in a Cochrane Clinical Answer that focuses on the above important clinical question.
Confidence in the evidence is moderate or low to moderate where GRADE has been performed and there may be no difference in effectiveness between the intervention and comparison for key outcomes.
Population: Adults with severe or very severe COPD experiencing exacerbations
Intervention: Systemic corticosteroids for seven days or fewer
Comparison: Systemic corticosteroids for longer than seven days
| Outcome | Effectiveness (BMJ rating)? | Confidence in evidence (GRADE)? |
|---|---|---|
Treatment failure (10–14 days) | No statistically significant difference | Moderate |
Relapse (14–180 days) | No statistically significant difference | Moderate |
Time to re‐exacerbation | No statistically significant difference | GRADE assessment not performed for this outcome |
FEV1 % predicted: 6 days | No statistically significant difference | GRADE assessment not performed for this outcome |
FEV1 % predicted: 30 days | No statistically significant difference | GRADE assessment not performed for this outcome |
Dyspnoea | No statistically significant difference | GRADE assessment not performed for this outcome |
Quality of life: 6 days | No statistically significant difference | GRADE assessment not performed for this outcome |
Quality of life: 30 days | No statistically significant difference | Moderate |
Duration of hospital stay | No statistically significant difference | Moderate |
Adverse effects: hyperglycaemia | No statistically significant difference | Moderate |
Adverse effects: hypertension | No statistically significant difference | GRADE assessment not performed for this outcome |
Adverse effects: other ᵃ | No statistically significant difference | Low |
Note The Cochrane Clinical Answer (CCA) noted that the number of participants included in the meta-analyses for the primary outcomes of treatment failure and relapse may be too small (450 and 478 participants) to detect differences between treatment groups. The Cochrane review which underpins the CCA noted that one large study carried most of the weight in the meta-analysis, and was therefore responsible for the confidence in the conclusion that shorter courses of oral corticosteroids (for five days) can be used as treatment for COPD exacerbation as they seem to be equally effective as longer courses. The Cochrane review which underpins this CCA noted that the reviewed studies did not include people with mild or moderate COPD and future studies are required in this patient group. The Cochrane review also reported two outcomes not included in the CCA (mortality: no statistically significant difference between treatment groups, moderate GRADE rating; lung function [end of treatment; FEV1; 10–14 days]: no statistically significant difference between treatment groups, very low GRADE rating). ᵃ Other adverse effects included gastrointestinal tract bleeding, symptomatic gastrointestinal reflux, symptoms of congestive heart failure or ischaemic heart disease, sleep disturbance, fractures, and depression.
This evidence table is related to the following section/s:
This table is a summary of the analysis reported in a Cochrane Clinical Answer that focuses on the above important clinical question.
Confidence in the evidence is moderate or low to moderate where GRADE has been performed and the intervention may be more effective/beneficial than the comparison for key outcomes.
Population: People with a clinical diagnosis of COPD (FEV1/FVC <70%) with a history of smoking
Intervention: Action plan (written guidance detailing self‐initiated interventions such as changing medication regime or visiting a GP or hospital) in response to changes that may suggest the start of an acute exacerbation of COPD ᵃ
Comparison: Usual care (no access to the action plan)
| Outcome | Effectiveness (BMJ rating)? | Confidence in evidence (GRADE)? |
|---|---|---|
Hospitalisations for COPD/100 patient years (follow up: 12 months) | No statistically significant difference | Moderate |
At least 1 hospital admission (follow up: 12 months) | Favours intervention | Moderate |
Hospitalisations & emergency visits for COPD/100 patient years | Favours intervention | High |
Courses of oral corticosteroids: 12 months | Favours intervention | Moderate |
Courses of antibiotics: 12 months | Favours intervention | Moderate |
FEV1 % predicted: 6 months | No statistically significant difference | GRADE assessment not performed for this outcome |
FEV1 % predicted: 12 months | No statistically significant difference | GRADE assessment not performed for this outcome |
Quality of life measured by St George's Respiratory Questionnaire (SGRQ) overall score: 6–12 months | Favours intervention | Moderate |
Mortality (all cause): 12 months | No statistically significant difference | Moderate |
Note ᵃ Accompanied by a single short educational component along with ongoing support directed at use of the action plan, but without a comprehensive self‐management programme.
This evidence table is related to the following section/s:
Cochrane Clinical Answers
Cochrane Clinical Answers (CCAs) provide a readable, digestible, clinically focused entry point to rigorous research from Cochrane systematic reviews. They are designed to be actionable and to inform decision making at the point of care and have been added to relevant sections of the main Best Practice text.
- How does longer corticosteroid treatment (>7 days) compare with shorter (≤7 days) in people with exacerbations of chronic obstructive pulmonary disease?
- How does non-invasive ventilation compare with usual care in people with acute hypercapnic respiratory failure due to exacerbation of chronic obstructive pulmonary disease?
- What are the effects of hospital-at-home in adults with acute exacerbations of chronic obstructive pulmonary disease?
- What are the effects of action plans with limited patient education only in reducing exacerbations of chronic obstructive pulmonary disease?
Use of this content is subject to our disclaimer