Health Dictionary
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Pack year
Introduction
A pack year is a quantification of cigarette smoking.
Definition
Definition
A way to measure the amount a person has smoked over a long period of time. It is calculated by multiplying the number of packs of cigarettes smoked per day by the number of years the person has smoked. For example, 1 pack year is equal to smoking 1 pack per day for 1 year, or 2 packs per day for half a year, and so on.[1]
Calculating ‘Pack Years’
Calculating ‘Pack Years’
Number of pack years = (number of cigarettes smoked per day x number of years smoked)/20
For example: a patient who has smoked 15 cigarettes a day for 40 years has a (15×40)/20 = 30 pack year smoking history. (1 pack has 20 cigarettes).
A pack-year is smoking 20 cigarettes a day for one year. If someone has smoked ten cigarettes a day for six years they would have a three pack-year history. Someone who has smoked forty cigarettes daily for twenty years has a forty pack-year history.
Significance and Usage
Significance and Usage
Quantification of pack years smoked is important in clinical care where degree of tobacco exposure is closely correlated to risk of disease.
References
References
- ↑ http://www.cancer.gov/Templates/db_alpha.aspx?CdrID=306510 National Cancer Institute Definition of Pack Year