IHP 330 Module Two Worksheet (1)
docx
keyboard_arrow_up
School
Southern New Hampshire University *
*We aren’t endorsed by this school
Course
330
Subject
Health Science
Date
Jul 2, 2024
Type
docx
Pages
4
Uploaded by MinisterWater43194
IHP 330 Module Two Worksheet
Complete this worksheet by replacing the bracketed text with the relevant information.
Part 1: Measuring Disease
A causal relationship between cigarette smoking and lung cancer was first suspected in the 1920s based on clinical observations. To test this apparent association, numerous epidemiologic studies were undertaken between 1930 and 1960. Two studies were conducted by Richard Doll and Austin Bradford Hill in Great Britain. The first was a case-control study begun in 1947; it compared the smoking habits of lung cancer patients with the smoking habits of other patients. The second was a cohort study begun in 1951; it recorded causes of death among British physicians in relation to smoking habits. This case study deals first with the case-control study and then with the cohort study.
Data for the case-control study were obtained from hospitalized patients in London and the vicinity over a four-year period (April 1948–February 1952). Initially, 20 hospitals, and later more, were asked to notify the investigators of all patients admitted with a new diagnosis of lung cancer. These patients were then interviewed concerning smoking habits, as were controls selected from patients with other disorders (primarily nonmalignant) who were hospitalized in the same hospitals at the same time. Data for the cohort study were obtained from the population of all physicians listed in the British Medical Register who resided in England and Wales as of October 1951. Information about present and past smoking habits was obtained by using a questionnaire. Information about lung cancer came from death certificates and other mortality data recorded during the ensuing years.
Over 1700 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 the initial lung cancer diagnosis proved to be 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:
Table 1: Relationship between cigarettes and lung cancer
Patient Type
Cases
Controls
Cigarette Smoker
1,350
1,296
Nonsmoker
7
61
Total
1,357
1,357
1.
Calculate the proportion of cases that smoked. Be sure to show your calculations.
1,350 ÷ 1,357= 0.99484156
99.48% 2.
Calculate the proportion of controls that smoked. Be sure to show your calculations.
1,296 ÷ 1,357= 0.9550479
95.5%
This worksheet was modified using information from the original case study found on the CDC website:
Centers for Disease Control and Prevention. (2003). Cigarette smoking and lung cancer. Centers for Disease Control and Prevention Epidemiology Program Office Case Studies in Applied Epidemiology
, 731–703. https://www.cdc.gov/eis/downloads/xsmoke-student-731-703.pdf
3.
Calculate the odds ratio with the correct equation, and interpret the calculation betweeen smoking and lung cancer. What can you infer from the odds ratio about the relationship between smoking and lung cancer?
(1,350 × 61) ÷ (1,296 × 7) = 82,350 ÷ 9,072 = 9.07738095
9.08 The odds ratio is calculated at 9.08. This shows that the people who are smokers are 9 times more likely to develop cancer than those individuals who do not smoke. Table 2 shows the frequency distribution of male cases and controls by the average number of cigarettes smoked per day.
Table 2: Daily Cigarette Consumption
Daily Number of
Cigarettes
Number of Cases
Number of Controls
Odds Ratio
0
7
61
Referent
1–14
565
706
6.97
15–24
445
408
9.50
25+
340
182
16.28
All smokers
1350
1296
9.08
Total
1357
1357
8.71
4.
Calculate the odds ratio by category of daily cigarette consumption, comparing each category to nonsmokers. Be sure to show your calculations. Replace the bracketed text with the calculated ratios.
o
(61 × 565) ÷ (7 × 706) = 34,465 ÷ 4,942 = 6.97389721
6.97 o
(61 × 455) ÷ (7 × 408) = 27,145 ÷ 2,856 = 9.5045518
9.50
o
(61 × 340) ÷ (7 × 182) = 20,740 ÷ 1,274 = 16.2794349
16.28
o
(61 × 1350) ÷ (7 × 1296) = 82,350 ÷ 9,072 = 9.07738095
9.08
o
(61 × 1357) ÷ (7 × 1357) = 82,777 ÷ 9,499 =8.71428571
8.71
5.
Interpret these results and describe the trends or patterns you see in the data.
The results shows the odds ratio increases when more cigarettes are smokes daily. This can increase the chances of cigarette smokers being diagnosed with lung cancer.
This worksheet was modified using information from the original case study found on the CDC website:
Centers for Disease Control and Prevention. (2003). Cigarette smoking and lung cancer. Centers for Disease Control and Prevention Epidemiology Program Office Case Studies in Applied Epidemiology
, 731–703. https://www.cdc.gov/eis/downloads/xsmoke-student-731-703.pdf
Part 2: The Cohort Study
Data for the cohort study were obtained from the population of all physicians listed in the British Medical Register who resided in England and Wales as of October 1951. Questionnaires were mailed in October 1951 to 59,600 physicians. The questionnaire asked the physicians to classify themselves into one of three categories: 1) current smoker, 2) ex-smoker, or 3) nonsmoker. Smokers and ex-smokers were asked about the
amount they smoked, their method of smoking, the age they started to smoke, and, if they had stopped smoking, how long it had been since they last smoked. Nonsmokers were defined as persons who had never consistently smoked as much as one cigarette a day for as long as one year. Physicians were also asked whether they had a diagnosis of lung cancer. Usable responses to the questionnaires were received from 40,637 (68%) physicians, of whom 34,445 were males and 6,192 were females. The next section of this case study is limited to the analysis of male physician respondents, 35 years of age or older. The occurrence of lung cancer in physicians responding to the questionnaire was documented over a 10-year period (November 1951 through October 1961) from death certificates filed with the Registrar General of the United Kingdom and lists of physician deaths provided by the British Medical Association. All certificates indicating that the decedent was a physician were abstracted. For each death attributed to lung cancer, medical records were reviewed to confirm the diagnosis.
Diagnoses of lung cancer were based on the best evidence available; about 70% were from biopsy, autopsy, or sputum cytology (combined with bronchoscopy or X-ray evidence); 29% were from cytology, bronchoscopy, or X-ray alone; and only 1% were from just case history, physical examination, or death certificate. In total, 355 cases of lung cancer occurred during this 10-year period, with 255 newly diagnosed cases of lung cancer.
Of 4,597 deaths in the cohort over the 10-year period, 157 were reported to have been caused by lung cancer; in 4 of the 157 cases, this diagnosis could not be documented, leaving 153 confirmed deaths from lung cancer. The following table shows numbers of lung cancer deaths by daily number of cigarettes smoked at the time of
the 1951 questionnaire (for male physicians who were nonsmokers and current smokers only). Person-years of observation (“person-years at risk”) are given for each smoking category. The number of cigarettes smoked was available for 136 of the persons who died from lung cancer.
6.
Calculate the incidence of lung cancer during the 10-year period. Be sure to show your calculations.
(145,400) ÷ (100,000) = 1.454
1.45
7.
Calculate the prevalence of lung cancer during this 10-year period. Be sure to show your calculations.
136/145,400 x 1,000 = 0.93535076
0.94
This worksheet was modified using information from the original case study found on the CDC website:
Centers for Disease Control and Prevention. (2003). Cigarette smoking and lung cancer. Centers for Disease Control and Prevention Epidemiology Program Office Case Studies in Applied Epidemiology
, 731–703. https://www.cdc.gov/eis/downloads/xsmoke-student-731-703.pdf
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
Table 3: Number and rate (per 100,000 person-years) of lung cancer deaths by number of cigarettes smoked per day, Doll and Hill physician cohort study, Great Britain, 1951–1961.
Daily Number of
Cigarettes Smoked
Deaths From
Lung Cancer
Person-Years
at Risk
Mortality Rate per
1,000 Person-Years
0
3
42,800
0.07
1–14
22
38,600
0.57
15–24
54
38,900
1.39
25+
57
25,100
2.27
All smokers
133
102,600
1.30
Total
136
145,400
0.94
8.
Calculate the lung cancer mortality rates for each smoking category. Be sure to show your calculations.
(22 ÷ 38,600) x 1,000 = 0.56994819
0.57 (54 ÷ 38,900) x 1,000 = 1.38817481
1.39
(57 ÷ 25,100) x 1,000 = 2.27091633
2.27
(133 ÷ 102,600) x 1,000 = 1.2962963
1.30
(136 ÷ 145,400) x 1,000 = 0.93535076
0.94
9.
Describe the trends or patterns you see in the data about mortality and explain what the trends or patterns mean.
The higher consumption of cigarettes smoked daily leads to a higher mortality rate.
This worksheet was modified using information from the original case study found on the CDC website:
Centers for Disease Control and Prevention. (2003). Cigarette smoking and lung cancer. Centers for Disease Control and Prevention Epidemiology Program Office Case Studies in Applied Epidemiology
, 731–703. https://www.cdc.gov/eis/downloads/xsmoke-student-731-703.pdf