Capturing total nicotine exposure in a multi-product landscape using Nicotine Product Days (NPDs)

With the popularity of noncombustible nicotine products among young people —such as e-cigarettes and nicotine pouches—and the decline in combustible tobacco use, it remains unclear how overall nicotine exposure and its potential long-term health risks have evolved. The standard measure used by the Centers for Disease Control and Prevention—any tobacco product use in the past 30 days—does not account for frequency of use or differences in risk profiles across products.

To more comprehensively assess nicotine exposure, we developed an innovative measure: nicotine product days (NPDs), defined as the number of days an individual used any nicotine product in the past 30 days. NPDs are additive across products and range from 0 to 30, where 0 indicates no use and 30 indicates daily use. We also constructed product-specific NPDs to reflect potential differences in health risks across nicotine products. Using all available waves of the Population Assessment of Tobacco and Health Study, we examined trends in overall and risk-adjusted NPDs among US adolescents and young adults over time. In addition, we assessed how overall and risk-adjusted NPDs vary across key sociodemographic groups.