Question

The death rate per 100,000 for lung cancer is 7 among non-smokers and 71 among smokers. The death rate per 100,000 for coronary thrombosis is 422 among non-smokers and 599 among smokers. The prevalence of smoking in the population is 55%.The population etiologic fraction of disease due to smoking is:a.0.83 for lung cancer and 0.18 for coronary thrombosis.b.Cannot be determined from the information provided.c.0.80 for lung cancer and 0.28 for coronary thrombosis.d.0.83 for lung cancer and 0.28 for coronary thrombosis.e.0.80 for lung cancer and 0.18 for coronary thrombosis.

Answer 1

Answer:

A) 0.83 for lung cancer and 0.18 for coronary thrombosis.

Explanation:

For the population etiologic fraction due to smoking, we use the formula:

$= \frac{P_s(RR_s-1)}{(1+P_s(RR_s-1))}$

For lung cancer:

Given:

$P_s = 55percent = 0.55$

We first find RRs which is the relative risk of dying from cancer for a smoker compared to a non smoker.

$RR_s = \frac{num of smokers death}{num of non-smokers death}$

$= \frac{71}{7}$

= 10.1429

Therefore population etiologic fraction due to cancer wil be:

$\frac{0.55(10.1429-1)}{1+0.55(10.1429-1)}$

$= \frac{5.029}{6.029}$

= 0.8341

Population etiologic fraction of cancer due to smoking is 0.834

•For coronary thrombosis:

Let's use the formula:

$\frac{P_s}{RR_s-1}{1-P_s(RR_s-1}$

Let's first find the RRs (relative risk of dying from cornary thrombosis for a smoker compared to a non smoker)

$= \frac{599}{422}$

$RR_s = 1.4194$

The population etiologic fraction of cornary thrombosis due to smoking, will be:

$= \frac{0.55(1.4194-1)}{1+0.55(1.4194-1)}$

$= \frac{0.231}{1.231}$

= 0.187

The population etiologic fraction of cornary thrombosis due to smoking is 0.187

Therefore the answer is option (A) 0.83 for lung cancer and 0.18 for coronary thrombosis