NMS Q&A Family Medicine

chapter 41Concepts in Epidemiologyand Research MethodExamination questions : Unless instructed otherwise, choosethe ONE lettered answer or completion that is BEST ineach case.1 A study to investigate a new drug for primary preventionof colorectal cancer enlisted 400 subjects withhistories of adenomatous polyps by colonoscopy inthe treatment group and 400 subjects with historiesof adenomatous polyps in a placebo group, matchedfor age, sex, geography, and other variables. Theywere followed for 10 years, and the treatment grouphad a 3% incidence of colorectal cancers, whereas thecontrol group a 5% incidence. Assuming the studywas valid and results were statistically significantlydifferent in the two groups, how many patients,matched with the study group for age, sex, and riskfactors for colorectal carcinoma would you have totreat for 10 years to prevent one colorectal cancer?(A) 25(B) 50(C) 100(D) 200(E) 4002 Which of the following is an example of secondaryprevention?(A) Salt restriction to prevent onset of hypertension(B) Pap smears to prevent carcinoma of the cervix(C) Aspirin 80 mg daily to prevent vascularthrombotic disease(D) Angioplasty of the right coronary artery toprevent recurrence of angina pectoris(E) Prescription of simvastatin to correctdyslipidemia in a patient who has had amyocardial infarction3 Smoking cessation to prevent lung cancer is an exampleof which type of prevention?(A) Primary(B) Secondary(C) Tertiary(D) Quaternary(E) Common sense4 Which of the following is an example of tertiary prevention?(A) Resection of a carcinoma of the colon, found tobe in Duke’s stage A in a patient who presentedwith hematochezia.(B) Finding an elevated thyroid stimulatinghormone (TSH) in a patient whose T-4 and T-3are within normal limits and who has nosymptoms or a palpable goiter.(C) Removal of an adenomatous polyp duringscreening colonoscopy(D) Voluntary weight loss in a 50-year-old man withcentral obesity to prevent diabetes.(E) Carotid endarterectomy in a 57-year-old manwith an incidental finding of 80% stenosis ofthe right carotid artery.5 A new test for colorectal cancer is based on detectingcarcinoma DNA in stool. 1,000 subjects with firstdegree relative who had manifested either adenomatouscolon polyp or colorectal carcinoma were followedto test for the development of colorectal cancer.Annual colonoscopy by endoscopists who wereblinded to results of the new testing served as the“gold standard” for appearance in 1,000 subjects ofaverage risk followed over a period of 10 years. Overthe 10-year period there were 65 cases of cancer diagnosedby colonoscopy. Of these 63 tested positive tothe new stool test and 110 tested positive for the testwho did not have colorectal cancer upon colonoscopy.Which of the following figures represent thesensitivity of the new stool test (chances of a cancerof the colon being diagnosed by the new test)?(A) 63%(B) 89%(C) 90%(D) 36%(E) 100%249