PHP - Bad practice to assign an if condition to a variable?

Would assigning an if statements condition to a variable , then using that variable in the if statement be bad practice?

I just thought about this and tested:

<?php

$c1 = 3;
$test1 = (isset($c1) && $c1 >2);

if($test1){
    echo 'true';
}

else {
    echo 'false';
} 

Which actually works and does return true without any errors.

But even though it works, I want to make sure this isn't frowned upon.
The reason why I tried this, is because I'm creating a web app with over 8 dynamic filter options. Each of these options affect the others. This will allow me to cut down my code size and make it much neater.

For example:
Filter 1: Date range
Filter 2: Call Status (Answered/ Busy/ etc...)
Filter 3: Client Phone number

So if my user selects a date range, all filters will refresh and must only display the options that would be relevant in that range. (This I have working)

What are your thoughts on assigning a condition to a variable?