If it helps, you can easily quantify this using a Fisher exact...

If it helps, you can easily quantify this using a Fisher exact test. The Fisher exact test lets you answer any question in the form of “Is 3 out of 20 actually any different from 4 out of 19?”.

There are online calculators that let you plug in your values, then calculate a p-value for that set of observations, eg.:

https://www.socscistatistics.com/tests/fisher/default2.aspx

Using this test, there is no significant difference between the two treatment groups. (p=0.69, or 69% chance the two groups have the same dropout rate.) The two treatment groups are the same. But the treatment groups do have a higher dropout rate than the placebo group (p=.03).

The Fisher exact test is a really useful tool to know about whenever you want to compare results between to groups, and the online calculators make it very easy for anyone to use.