Kidney function endpoints in kidney transplant trials: a struggle for power

Area of Science:

• Nephrology
• Clinical Trials
• Biostatistics

Background:

• Kidney function is a key endpoint in kidney transplantation (KTx) randomized controlled trials (RCTs).
• Assessing the adequacy of sample sizes in ongoing KTx RCTs is crucial for reliable results.

Purpose of the Study:

• To estimate the proportion of KTx RCTs with adequate sample sizes to detect meaningful differences in glomerular filtration rate (GFR).
• To evaluate the statistical power of ongoing KTx RCTs based on their proposed sample sizes.

Main Methods:

• RCTs were identified from the National Institute of Health clinical trial registry using the keyword "kidney transplantation".
• Included trials tracked kidney function for at least 1 month post-transplant.
• Sample size adequacy was calculated for detecting minimum differences in GFR (5, 7.5, 10 mL/min) between two-arm parallel trials.

Main Results:

• Fifty RCTs met the inclusion criteria.
• Only 7% of trials had sufficient sample size to detect a 5 mL/min GFR difference (assuming 80% power, α=0.05, 10% loss to follow-up, SD=20 mL/min).
• This proportion increased to 36% when considering a 10 mL/min GFR difference.

Conclusions:

• A minority of KTx RCTs possess adequate statistical power to detect clinically relevant GFR differences.
• Underpowered trials may lead to the abandonment of potentially effective interventions, impacting patient care.