What is the 12-month prevalence rate of nicotine use?

• A. 15.5%
• B. 25.0%
• C. 20.0%
• D. 18.7%

Answer: (C)

The main idea here is understanding what 12-month prevalence means. It tells us the proportion of people who have used nicotine at least once in the past year. It’s a snapshot of recent use, not new cases or lifetime experience.

If the rate is 20.0%, that means about one-fifth of the population reported nicotine use during the previous 12 months, regardless of current cessation status. This differs from incidence, which would count only new users in that period, and from lifetime prevalence, which would count anyone who has ever used nicotine up to today.

The other numbers don’t fit because they would reflect different timeframes or measurement approaches (for example, shorter windows, or cumulative lifetime use). So 20.0% is the value that aligns with the definition of the 12-month prevalence in this context.