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Confidence interval interpretation — FRCA Primary MCQ

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HardStatistics and Evidence-Based MedicineConfidence interval interpretationFRCA Primary

A meta-analysis reports an odds ratio of 0.74 for myocardial infarction, with a 95% confidence interval of 0.58 to 0.94. Which interpretation is best?

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Correct answer: D — The result is statistically significant at the 5% level

The best answer is “The result is statistically significant at the 5% level”. The 95% confidence interval for the odds ratio lies wholly below the null value of 1.0, so the result is statistically significant at the conventional 5% level. It indicates lower odds in the treated group, but it does not give an absolute risk reduction or prove absence of bias.

Reference: NICE, Developing NICE guidelines: Reviewing evidence: https://www.nice.org.uk/process/pmg20/chapter/reviewing-evidence