Question

Over 1,700 patients with lung cancer, all under age 75, were eligible for the case-control study. About 15% of these persons were not interviewed because of death, discharge, severity of illness, or inability to speak English. An additional group of patients were interviewed but later excluded when initial lung cancer diagnosis proved mistaken. The final study group included 1,465 cases (1,357 males and 108 females). The following table shows the relationship between cigarette smoking and lung cancer among male cases and controls.

	Cases	Controls
Cigarette smoker	1,350	1,296
Non-Smoker	7	61
Total	1,357	1,357

Table 1. Smoking status before onset of the present illness, lung cancer cases and matched controls with other diseases, Great Britain, 1948-1952.

Question 9 (2 points) From this table, calculate the proportion of cases and controls who smoked. • Proportion smoked, cases: • Proportion smoked, controls:

Answer 1

Cigarette smoker cases = 1,350

Total Cases= 1,357

The Proportion of smoked cases = Cigarette smoker cases/ Total Cases

Therefore 1,350/1,357 = 99.5%

So the proportion of smoked cases = 99.5%

Cigarette smoker Controls = 1,296

Total Controls =1,357

The Proportion of smoked controls = Cigarette smoker controls / Total controls

Therefore 1,296/1,357 = 99.5%

So the proportion of smoked controls = 99.5%