A medical impairment rating is completed by an independent professional in an appointment known as an Impairment Rating Evaluation (IRE). The rating gives a percentage number – between 0 and 100 – to the level of impairment, so the worker, employer, and insurer can all understand how much the worker has been injured and how much the impairment will affect work. The results of the medical impairment rating determine how long a person might get benefits, how much compensation he might receive, and whether he’s expected to return to work.