What is the fine-grained topic of the following text: Results: The age frequency percentage in the intervention and control group was 40 % and 28.3 % in age range of 20-29, 26.7 % and 41.7 % in age range of 30–39, and finally 33.3 % and 30 % for the age over 40 years, respectively (p= 0.19). Only return the topic.
Age distribution in intervention and control groups