It’s easy to slip into shorthand when describing your results, especially if you are trying to stick to a set of character limits, but remember, your reader didn’t conduct this research.
You might know the difference between “group 1” and “group 2”, but everyone else will have to flip through the article to remember which is which.
That’s why you should use clear description, not codes, when you’re describing elements of your results.
So instead of writing:
Survival was greater in groups 1 and 2 than in controls.
Define each group in the text:
Survival was greater in the moderate-dose and high-dose groups than in untreated controls.