Survival rates of heart patients differ depending on marital status

Wall Street Journal reported today on a study about survival rates of heart patients:

In a study of nearly 600 heart-surgery patients, unmarried people were nearly twice as likely to die as married people within five years of the procedures. For married patients, the survival rate was roughly 85%; for the unmarried, 70%

I'm not sure how "nearly twice as likely to die" was calculated given the numbers:
25% of married patients die or 1 in 4, so twice as likely would be 2 in 4 of 50%.
Instead unmarried patients die at a rate of 30% or 1 in 3, not exactly "nearly". There is likely another calculation that is not jumping out at me.

Also, the bigger more revealing part of the story is here:

Much of the long-term difference could be explained by unmarried patients being more likely to smoke (a behavior that spouses can influence, naturally).

So the headline could have read "People who smoke are more likely to die than those who don't after heart surgery (oh, and people who smoke also have a higher chance of being single). But, then no one would read it ad it wouldn't make a heart warming (pun intended) story about how marriage can literally save your heart (of which I full heatedly (it's too easy) agree).

What would it mean to your business if a certain segment of customers was found to be less receptive to your offering and by less receptive I mean will be more likely to die?