The denominator is your overall patients that would qualify for the measure and would be your larger number of the two. Of you have a 0 for your denominator, then your numerator would be 0 as well. For example, For hypertension and blood pressure measurement your denominator is the number of patients who are 18 years and older who are diagnosed with hypertension. Your numerator is those patients in your denominator that have a controlled blood pressure. If you have no patients that qualify for your denominator (giving you a 0) then there will be a 0 as well for your numerator.
