The doctor was concerned about high mortality among those with the disease.
Explanation:
The word "mortality" refers to the state of death or the rate of death or the state of being mortal. This term generally signifies the state of being subjected to death or the nature of it.
In the sentence <em>"[T]he doctor was concerned about high mortality among those with the disease"</em>, the use of the term "mortality" is correct. This is because as "mortality" refers to the state of death, the doctor's concern about the high death rate among the people is correct sentence construction.
