Development of a drug that could potentially modify the course of Parkinson’s disease is extremely challenging. A design that has been proposed for such a claim is delayed start design. In this design, a comparison is made between the patients who are early randomized to treatment vs. who are initially randomized to placebo are given active treatment after certain weeks. If the early start treatment group has a lower mean clinical score compared to the mean score of the delayed start treatment group at the end of study period, the drug has disease modifying benefit.

Clinical trial simulations are conducted to evaluate the statistical properties of different statistical approaches often used to analyze incomplete data from delayed start design. A statistical methodology is proposed to analyze incomplete data from a delayed start design trial.