Sample Size Calculation for Phase 3 Non-Inferiority Trial Comparing Nebivolol and Bisoprolol for Hypertension in China

To calculate the sample size, the following information is needed:

1. The type I error rate (alpha) - typically set at 0.05
2. The type II error rate (beta) - typically set at 0.10 (90% power)
3. The non-inferiority margin - this is the maximum difference between the two treatments that is considered clinically acceptable. For this study, let's assume a non-inferiority margin of 2 mmHg in systolic blood pressure.
4. The standard deviation of the primary endpoint - let's assume a standard deviation of 10 mmHg in systolic blood pressure.
5. The dropout rate - let's assume a dropout rate of 20%.

Using these assumptions, the sample size can be calculated using the following formula:

n = (Zα/2 + Zβ)^2 x (2σ^2 + Δ^2) / Δ^2

Where:

• Zα/2 is the z-score for the chosen alpha level (1.96 for 0.05)
• Zβ is the z-score for the chosen beta level (1.28 for 0.10)
• σ is the standard deviation of the primary endpoint
• Δ is the non-inferiority margin

Plugging in the values, we get:

n = (1.96 + 1.28)^2 x (2 x 10^2 + 2^2) / 2^2 n = 226.27

Adjusting for the dropout rate, the final sample size is:

n_final = n / (1 - dropout rate) n_final = 226.27 / (1 - 0.20) n_final = 282.84

Therefore, a total of 283 patients (141 per treatment group) will be needed for this study.