Pack-years is a clinical metric used to quantify a person's lifetime exposure to tobacco smoke, which is a major lifestyle risk factor for non-communicable diseases such as cardiovascular disease and lung cancer.
Table 1 shows the smoking habits and calculated cumulative pack-years for two patients at a medical clinic.
| Patient | Average cigarettes smoked per day | Years as a smoker | Cumulative Pack-Years |
|---|---|---|---|
| Patient A | 25 | 16 | ? |
| Patient B | 15 | 30 | 22.5 |
Use the following formula to calculate the cumulative pack-years for Patient A.
Pack-years=Cigarettes smoked per day20×Years smoking \text{Pack-years} = \frac{\text{Cigarettes smoked per day}}{20} \times \text{Years smoking} Pack-years=20Cigarettes smoked per day×Years smoking
