[Let's stop using packet-years as expression of tobacco consumption]

Area of Science:

• Public Health
• Epidemiology
• Tobacco Control

Background:

• Cigarette consumption is commonly quantified using "pack-years" (packs per day multiplied by years smoked).
• This metric aims to provide a single summary of an individual's cumulative tobacco exposure.
• However, the relevance of this measure for health impact studies is questionable.

Purpose of the Study:

• To evaluate the relevance of the "pack-year" metric in summarizing tobacco consumption for health studies.
• To propose a more appropriate single metric for tobacco consumption relevant to health outcomes.

Main Methods:

• Conceptual analysis of the "pack-year" metric.
• Comparison of the relative impact of smoking dose versus duration on health outcomes.

Main Results:

• The "pack-year" metric assumes equal weighting for dose and duration of smoking.
• The health impact of smoking duration is significantly greater than the impact of dose.
• Duration of exposure is a more critical factor than the number of cigarettes smoked per day.

Conclusions:

• The "pack-year" metric is not ideal for studying the health effects of tobacco.
• Smoking duration is a more relevant summary measure for assessing tobacco's impact on health.
• Future research should prioritize duration of exposure when summarizing smoking history.