"Don't Know" Responses for Nicotine Vaping Product Features among Adult Vapers: Findings from the 2018 and 2020 ITC Four Country Smoking and Vaping Surveys.

Nicotine vaping products (NVPs) have evolved rapidly, and some vapers have difficulty reporting about their NVP. NVP knowledge may be important for providing accurate survey data, understanding the potential risks of NVP use, and assessing legal and regulated products. This paper examines current vapers who responded "don't know" (DK) regarding their NVP features. Data are from adult daily/weekly vapers in Waves Two (2018, = 4192) and Three (2020, = 3894) of the ITC Four Country Smoking and Vaping Survey. Analyses assessed DK responses for NVP features (e.g., type/appearance, nicotine) and consumption. A DK index score was computed based on the percent of all features with DK responses, which was tested for associations with demographics, smoking/vaping status, NVP features, purchase location, and knowledge of NVP relative risks. NVP description and appearance were easily identified, but DK was more common for features such as nicotine content (7.3-9.2%) and tank/cartridge volume capacity (26.6-30.0%). DK responses often differed by vaping/smoking status, NVP type/appearance, purchase location, and country. Vapers who are younger, use box-shaped NVPs, purchase online, and exclusive daily vapers were associated with lower DK index scores. Higher DK index scores were associated with poorer knowledge of relative health risks of NVP use. The diversity of the NVP market and wide variation in how products are used makes it challenging to capture information from users about device features, such as nicotine content and capacity, in population surveys.