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: Adults (mean age 53‐77 years; 70% male) with symptomatic chronic subdural hematoma
Intervention: External subdural drainage after burr‐hole evacuation
Comparison: No drains
| Outcome | Effectiveness (BMJ rating)? | Confidence in evidence (GRADE)? |
|---|---|---|
Recurrence (follow‐up: 3 weeks to 6 months) | Favors intervention | Moderate |
Postoperative complications (follow‐up: 3 weeks to 6 months) | No statistically significant difference | Low |
Mortality (follow‐up: 6 months) | No statistically significant difference ᵃ | Low |
Poor functional outcome (including death) (follow‐up: 6 months) | No statistically significant difference | Low |
Note The Cochrane Clinical Answer (CCA) noted that the effect of drainage on postoperative complications, mortality, and poor functional outcome remains unclear due to the low quality of the evidence. The Cochrane review which underpins this CCA noted that further research regarding the effectiveness of single versus double burr holes, irrigation versus no irrigation, drainage catheter position, and duration of drainage are needed. ᵃ Absolute effect 78 per 1000 people (95% CI 45 to 133) with drains compared with 100 per 1000 people with no drains.
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 do external drains compare with no drains after burr-hole evacuation for chronic subdural hematoma?
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