Dr. Regillo: The treat-and-extend and treat-and-observe approaches are, by definition, a way to individualize anti-VEGF therapy to treat patients with wet AMD. The treat-and-extend has become the more popular regimen used over the years, because for each patient you find that [treatment] interval that seems to work best, but you're treating at every visit so you hope to minimize recurrences and keep the visual gains optimally high. It is more convenient than a frequent-and-fixed regimen, and it may be also more convenient for patients compared to a treat-and-observe protocol because the treat-and-observe does require very frequent follow-up for our patients to keep on top of the disease and identify those recurrences when they do occur. So the treat-and-extend does help to minimize the cost burden of follow up and management of follow up, and for all those reasons has become the preferred technique for retina specialists in the United States over the past few years.
That being said, the potential advantage of a treat-and-observe, or PRN [pro re nata; as needed], approach compared to treat-and-extend or even continuous therapy of any type is that it does allow you to identify the occasional patient who does not need ongoing therapy. Therefore, it effectively becomes the most cost-effective approach, because you don't continue to treat. But you still need to observe those patients closely, so there is still the burden of the patient coming to the office on a regular and frequent basis.
Some major clinical studies, such as the [US] CATT trial1,2 or the IVAN3 study out of the UK, do show that, on average, PRN therapy, which is the
So, over time, the treat-and-observe approach may in some patients be suboptimal. And why is that the case? Well, because when you