Statistical power in parallel group point exposure studies with time-to-event outcomes: an empirical comparison of the performance of randomized controlled trials and the inverse probability of treatment weighting (IPTW) approach

BMC Medical Research Methodology

Robert W. Platt²  Tibor Schuster¹  Peter C. Austin³ 

[1] Department of Paediatrics, University of Melbourne, Melbourne, Australia;Department of Pediatrics, McGill University, Montreal, Canada;Schulich Heart Research Program, Sunnybrook Research Institute, Toronto, Canada

关键词: Monte Carlo simulations;    Randomized controlled trial;    Survival analysis;    Causal inference;    Inverse probability of treatment weighting;    Propensity score;    Observational study;   

Others  :  1230342
DOI  :  10.1186/s12874-015-0081-3

 received in 2015-03-11, accepted in 2015-10-05,  发布年份 2015

【 摘 要 】

Background

Estimating statistical power is an important component of the design of both randomized controlled trials (RCTs) and observational studies. Methods for estimating statistical power in RCTs have been well described and can be implemented simply. In observational studies, statistical methods must be used to remove the effects of confounding that can occur due to non-random treatment assignment. Inverse probability of treatment weighting (IPTW) using the propensity score is an attractive method for estimating the effects of treatment using observational data. However, sample size and power calculations have not been adequately described for these methods.

Methods

We used an extensive series of Monte Carlo simulations to compare the statistical power of an IPTW analysis of an observational study with time-to-event outcomes with that of an analysis of a similarly-structured RCT. We examined the impact of four factors on the statistical power function: number of observed events, prevalence of treatment, the marginal hazard ratio, and the strength of the treatment-selection process.

Results

We found that, on average, an IPTW analysis had lower statistical power compared to an analysis of a similarly-structured RCT. The difference in statistical power increased as the magnitude of the treatment-selection model increased.

Conclusions

The statistical power of an IPTW analysis tended to be lower than the statistical power of a similarly-structured RCT.

【 授权许可】

   
2015 Austin et al.

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