Error using get_user_message_registry()

I had this error when using {% if get_user_message_registry() > 0 %} in twig :
1/1 ContextErrorException: Notice: Object of class CCDNMessage\MessageBundle\Entity\Registry could not be converted to int in /var/www/montagne-cable/app/cache/dev/twig/4e/c4/05c26c9e49533701d53c57223acb4b20d27b93f5b8ece9f7a3c51eaaac75.php line 100
