You did not say it but the research did not say you would be 5x safer in a house without a gun. It said you would be five times less likely to be killed with a gun. 3.2 million people die in the US each year. 50,000 of those were firearms related and half of those were suicide. Having guns in the house is an almost trivial additional risk unless someone is considering suicide. You don't also consider how many people were not killed because they had a gun and either used it in active self-protection or as a deterrent. For stupid people without proper firearms training there is some small added risk. For a capable person with proper firearms training having a gun in the house makes them safer.

If there are no children in the house the risk for accidents goes way down.

TEK