returns null

<?php
class Connection {

    protected $host = "localhost";
    protected $dbname = "aaron_aaron";
    protected $user = "aaron_aaron";
    protected $pass = "d6G4X5S54";
    protected $DBH;

    function __construct()
    {
        try {
            $this->DBH = new PDO("mysql:host=$this->host;dbname=$this->dbname", $this->user, $this->pass);
        }
        catch (PDOException $e)
        {
            echo $e->getMessage();
        }
    }
	public function getMembers()
	{
		$sth = $dbh->prepare("SELECT * FROM members");
		$sth->execute();
		$result = $sth->fetchAll();
	}
}

$dbh = new Connection($host,$dbname,$user,$pass);

var_dump($result);


 ?>