Understanding PHP MySQL Prepared Statements Security

I made the following prepaid statement.
id:int type, name:varcher type, area:int type.
Assume area is a number from 1 to 10 that represents the position where you live.
For example, 1=Kanto, 2=Kansai, 3=Shikoku, ...

In this case, how do I retrieve user data for all regions?

For example,

 if($area==0){
  $db->query("SELECT id, name FROM user");
} else {
  $ps=$db->prepare("SELECT id, name FROM user WHERE area=:area");
  $ps->bindValue(':area', (int)$area, PDO::PARAM_INT);
  $ps->execute();
}

Is there no security problem with this?