Not really my area, but I believe that a relative risk of 1 means that the two groups have the same risk. Lower numbers mean lower risk for a given group. A relative risk of 0.55 is about half the risk.
I don’t think so. Relative risk of 0.55 means the blah-blah are only 55% as likely to be injured as bleh-bleh. The ratio would be 1.0 if the risks were the same.
The “adjusted” in adjusted relative risk might refer to various adjustments but I think means that the numbers have been fiddled to make them more valid, not less!
55% Relative risk means the probability of having an event at a particular instant in time under situation A is 55% of what it is in situation B. Equal risk would be a value of 1.0. Note this doesn’t mean that the overall chance of having that event is less, it may mean that you are more likely to go longer before it occurs…
As an illustration of this, suppose that every day you roll a die and on a roll of a 6 you die. Meanwhile your friend is in a worse situation and so every day he rolls the die and is killed on the roll of either a 5 or a 6. You would have a relative risk of compared to him of 50% but both of you are have a near 100% likelihood of dying within the next month.