A trial of 50 000 patients finds a reduction in systolic blood pressure of 0.5 mmHg with a p-value of less than 0.001. What is the best interpretation?
Answer and explanation
Correct answer: B. Statistically significant but of doubtful clinical importance
- Step 1: Large samples can detect tiny differences.
- Step 2: A small p-value indicates the result is unlikely by chance but says nothing about the size of benefit to patients.
Answer
Statistically significant but of doubtful clinical importance.
Why not the others: Not statistically significant: The p-value is below 0.001, so it is significant. Proof that the drug saves lives in patients with high blood pressure: Blood pressure change alone does not prove mortality benefit. Statistically significant and clinically highly important: 0.5 mmHg is clinically trivial.
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