Skip to contents

Calculate Standardized Mean Difference (SMD) Between RCT and RWE Results

Source: R/smd_agreement.R
smd_agreement.Rd

This function calculates the standardized mean difference (SMD) between results from a randomized controlled trial (RCT) and its real-world evidence (RWE) emulation. The SMD provides a measure of agreement between the two results, taking into account both the point estimates and their corresponding uncertainty.

Usage

smd_agreement(
  rct_estimate,
  rct_lower,
  rct_upper,
  rwe_estimate,
  rwe_lower,
  rwe_upper
)

Arguments

rct_estimate

Numeric. Point estimate from the RCT (typically log hazard ratio or log odds ratio)

rct_lower

Numeric. Lower bound of the confidence interval from RCT

rct_upper

Numeric. Upper bound of the confidence interval from RCT

rwe_estimate

Numeric. Point estimate from the RWE study

rwe_lower

Numeric. Lower bound of the confidence interval from RWE

rwe_upper

Numeric. Upper bound of the confidence interval from RWE

Value

Returns a numeric value representing the standardized mean difference. Larger absolute values indicate greater disagreement between RCT and RWE results.

Details

The SMD is calculated as the difference between RCT and RWE estimates, divided by the square root of the sum of their variances. Variances are derived from the confidence intervals assuming normal distribution (using 1.96 for 95

The formula used is: SMD = (theta_RCT - theta_RWE) / sqrt(Var(theta_RCT) + Var(theta_RWE))

References

For methodology on comparing RCT and RWE results using standardized differences.

Examples

# Example with hazard ratios (log scale)
smd <- smd_agreement(
  rct_estimate = log(0.87),
  rct_lower = log(0.78),
  rct_upper = log(0.97),
  rwe_estimate = log(0.82),
  rwe_lower = log(0.76),
  rwe_upper = log(0.87)
  )