Two of my friends (one male and one female) died suddenly in the past year. Pluto isn't squaring my Mars or Venus, but is applying quincunx to my sun and has been for the past year, year and a half or so.
That's not a hard and fast predictive tool, though. Quincunxes may be common as transits to the charts of the surviving friends, but that doesn't mean you'll definitely have a friend die whenever you have a transiting quincunx to your chart. For me, those two deaths really stand out because they happened so close together and these were relatively young people who just suddenly dropped dead, and as far as I know, the only connection between them is that they both knew me. They might have known others in common too, but if so, I'm not aware of it.