The draft guidance also contains the agency’s first-ever written recommendations on study design and duration, follow-up, clinical endpoints, safety considerations, and more.
Plan on a minimum of 12 months of patient follow-up and be prepared to justify any follow-up period of less than 24 months based on projected risks and benefits.
All patients should undergo a washout period of all IOP-lowering medications before surgery to establish a baseline IOP. If IOP-lowering medications are restarted after surgery, patients need another washout period prior to IOP measurement and other data collection used in effectiveness analyses.
The recommended primary endpoint is the percentage of subjects with a reduction of at least 20% in mean diurnal IOP from baseline. The recommended secondary endpoint is the mean diurnal IOP change from baseline.
Other recommended analyses include percent reduction in mean diurnal IOP changes in the mean, range, and maximum of diurnal IOP measurements with box-plots for mean, range, and maximum of diurnal IOP; fluctuation of IOP measurements over time; changes in numbers of medications used; and an assessment of balance in baseline variables.
The draft guidance is a point from which to begin discussions with the FDA, Dr. Chambers said. It will not put an end to current applications in which similar devices with similar mechanisms of action are proceeding along different pathways.
One device might aim for a 510(K) approval with a 75-patient study. Another, seemingly identical device, might aim for Premarketing Approval with a 550-patient study. What the agency hopes it will do is encourage developers to work with the FDA early and often to determine which pathway and what types of studies are more appropriate for the most expeditious approval possible.