In this context age is not relevant as I am using the "synonym of man" definition of "boy"

I am talking about the fact that there are non-boys with penises (Such as myself, I am AMAB agender) and boys without penises.

There are better terms that could be used here. In this particular case, for example:

“The incidence of pathological phimosis is 0.4 per 1000 boys per year or 0.6% of boys are affected by their 15th birthday.”

“The incidence of pathological phimosis is, counting only people who have penises, 0.4 per 1000 people per year; 0.6% are affected by their 15th birthday.”

Less concise but accuracy>conciseness in this context