Table 16 Source of data on mentholation status in the lung cancer studies

American Health Foundation study [68]

Subjects were asked about lifetime history of brands of cigarettes smoked (up to 7 brands per person) and information was obtained on whether all brands reported were mentholated or not. If the brand name could not be recalled, the mentholation status was recorded.

Kaiser Permanente study [51]

Subjects were asked about the brand of the cigarette currently smoked and on whether the brand was mentholated or not. The authors did not report that they had obtained information on which brands were mentholated, or that they had checked one answer against the other.

Los Angeles County study [69]

Mentholated cigarette use was based on the question "On average over your lifetime, out of every 100 cigarettes you smoked, how many were menthol?"

Slone Epidemiology Center study [53]

Subjects were asked about the most recent brand and the brand used for the longest period of time to determine the brand name and whether it was mentholated or not. The consistency of the brand name and menthol status was not checked. In some analyses, cigarettes smoked prior to 1956 were assumed not to be mentholated.

Second American Health Foundation study [83]

Details are not given in the methods, but the variable analyzed related to whether current smokers preferred mentholated cigarettes.

German study [84]

Subjects were asked about their smoking history including brand names, with exposure to mentholated cigarettes derived from the brand names blinded for case-control studies.

Lung Health study [56]

At baseline subjects were asked "Do you now smoke cigarettes?" followed by "What type of cigarettes are they? Are they plain or menthol?" Similar questions were asked at annual follow-ups but the answers were not used in the analyses related to risk of lung cancer.

Houston study [85]

Smokers were asked to report their use of mentholated cigarettes, with ever use the endpoint used for analysis.