Meta-Analysis: A Worked Example
Jan 05, 2025
Scenario: You are reviewing a meta-analysis on the effectiveness of a new drug for treating hypertension. The meta-analysis includes 10 randomized controlled trials (RCTs) comparing the new drug to a placebo.
Steps to Interpret:
- Research Question: The meta-analysis aims to determine if the new drug significantly reduces systolic blood pressure compared to placebo.
- Systematic Review: The review used comprehensive search strategies, clear inclusion criteria, and assessed study quality using the Cochrane risk of bias tool.
- Included Studies: The studies included in the meta-analysis have similar patient populations, intervention protocols, and outcome measures.
- Effect Size: The overall effect size shows a mean reduction of 5 mmHg in systolic blood pressure with a 95% confidence interval of 3 to 7 mmHg, which is statistically significant.
- Heterogeneity: The I² statistic is 30%, indicating low to moderate heterogeneity.
- Forest Plot: The forest plot shows consistent results across most studies, with the diamond indicating a significant overall effect.
- Publication Bias: The funnel plot is symmetrical, suggesting no significant publication bias.
- Interpretation: The new drug appears to effectively reduce systolic blood pressure. Given the low heterogeneity and lack of publication bias, the findings are robust and can be considered in clinical practice.
Conclusion
Interpreting a meta-analysis involves a thorough assessment of the systematic review process, evaluation of effect sizes, examination of heterogeneity, and consideration of potential biases. By following these steps, we can effectively interpret meta-analyses and apply the findings to inform evidence-based clinical decisions.
