Models that have ben resurrected or have been treated with emergency medical aid may suffer complications in surgery, as you might expect. This reflects the fact that dead guys should really stay dead, and people heal best when left to do it over time.
Some of the bad results on the table are stat reductions, as physical or mental faculties are degraded in the process of either bringing them back from death or rushing their healing. But what happens if the model in question has a “-” value for the stat to be reduced? The answer is simple: nothing. Well, nothing bad, at least. They recover without mishap as if they had rolled a 6-8 result.
Now this has caused a few highly analytical folk to raise their eyebrows. Surely this gives models with “-” stats an advantage? Well yes, technically it does. In the unlikely situation that a model reduces their stat to the worst it could possibly be they will die, and a model with a “-” value for this stat is obviously immune to this. However, this is only a very slight benefit indeed. To start with, there are only 2 models currently in the game that have a 7+ stat, and could threfore die with one bad roll. All other models need to get themselves into this situation repeatedly and then you have to have and choose to spend the points to resurrect or buy emergency care, and then they have to roll exactly the same result again. So yes, being able to avoid this is a bonus, but a tiny one. Most people won’t ever see a model die from reducing a stat this way.
Remember also that the model with this supposed advantage is also labouring under a complete lack of that stat, and so are already at a (IMO rather bigger) disadvantage. The most common stats to lack are Shoot and Command; the former limits your combat ability and the latter can trigger a lost battle. Both are things I think hugely outweigh any benefit that may accrue in the very rare (and somewhat self-infllicted) situation of repeated complications.