Question

Currently, large body of evidence in the world that smoking is the cause of numerous life-threatening diseases such as cardiovascular and pulmonary diseases along with different kinds of cancer. Despite the wamings given in the media and press, the number of smokers is escalating day by day. A case study conducted on 117 male students aging from19 to 27 years old. The 88 smokers had a history of consuming at least 5 cigarettes a day for at least 2 years. The case with lung cancer for smokers is 33 and 2 for non-smokers. Calculate the ratio of incidence of the disease among the exposed and incidence among the non- exposed and the amount or proportions of disease that can be attributed to a specific exposure. Discuss your results and recommendations.

Answer 1

• It is a type of cohort study which starts with risk factor and low risk factor.
• It is a prospective study.(forward)
• If proceeds from cause to effect or risk factor to disease.

Now we create 2 × 2 table.

Lung cancer no lung cancer

Smokers. 33. 55. 88

Non smokers. 2. 27 29

35. 82

Incidence:-

It is a rate of new cases diagnosed in a population during study.

1) incidence of disease among exposed

= Smokers having lung cancer/ total no of smokers

=33/88

= 0.375

2) incidence of disease among non exposed

= Non smokers having lung cancer/ total number of non smokers

= 2/29

= 0.068

3) relative risk

It is used to measure the risk of disease ine exposed to non exposed.

RR = incidence of disease in exposed/ incidence of disease in non exposed.

=

= 5.43

The risk of lung Cancer among smokers 5.43 times greater than the non smoker.

4) attributable risk (AR)

AR

= (Incidence of exposed -incidence of norm exposed)/ incidence of exposed

= (33/88 - 2/29) / (33/88)

= 1- 0.183

= 0.817

It is the percentage attributed by a risk factor in causing a disease.

Hear it one percent of lung cancer occurs due to smoking.

Interpretation:-

There is a positive association of smoking with a lung cancer because RR >1.

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