Slade said that Carlisle were always up against it following Lee Miller's early red card and that he was sure that Greg Abbott's side would be safe this season.
"I feel for Greg, who is a good friend of mine, because with all the preparation you do you can't legislate for that first half and Miller getting sent off," he told reporters.
"We were at the top of our game, but I'm sure Carlisle will be fine. Things conspired against them and I'm just happy to get that first win under our belts.
"We have taken the first step, but there's still a lot of work to be done and I thought we showed our adaptability."
Orient have scored 13 goals in their last three league games against Carlisle.