For every numerator, you need a denominator: a simple statement but key to measuring the quality of care of the "dying".

A mathematical rate is composed of a numerator, denominator, and time period of observation. Deciding who is in the denominator is a key, yet difficult task given the blurred boundaries of chronic illness, in examining the quality of care for dying patients. We propose two potential solutions. First, one could prospectively define the outcome state of "living with life-threatening" illness, where there is life expectancy of 1 or 2 years. Second, retrospective interviews could be used with family members or other loved ones about their perceptions of the quality of care in the last weeks of life. Improving the quality of care for dying patients and their families requires attention to this matter.