PHRM3031 Lecture Notes - Lecture 5: Cohort Study, Confounding, Relative Risk

41 views2 pages

goldfox889

10 Aug 2018

School

Department

Pharmacy

Course

PHRM3031

Professor

Adam La Caze

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Prevalence = number of cases / total population at a specified time. Incidence = number of new cases / total population at risk per unit of time. Occurrence of lung cancer in 10,000 people at risk of disease over a three year period. At risk => free from disease or condition. All participants who ceased to have lung cancer died. 4 people had lung cancer at the start of the study. 16 people developed lung cancer during the study. Prevalence: fraction of participants with condition at any given point in time. Incidence: fraction of participants initially free of condition who develop the condition over a given time. During the 3-year study: 16/9 996 (4 participants had lung cancer at the start of the study) During 2012: 5/9 985 (15 participants had lung cancer prior to the start of 2012) Incidence density = number of new cases / number of person years at risk of exposure.

Related Questions

do you agree or disagree and why? + source of the information:

A prevalence proportion differs from an incidence rate by specified cases and time period. A prevalence rate focuses on all kinds of existing cases while incidence rate focuses on new cases of disease. Incidence rate is calculated by dividing the number of new cases over a certain period of time by the population number that is at risk at that same time. The prevalence proportion can be calculated by the number of all existing illness and deaths at a specific time divided by the number of people in that population. There is also point prevalence, which the prevalence is measured at a certain point and period prevalence which measures prevalence over a period of time. To estimate the future risk of breast cancer among women aged 50-65, Incidence rate would be a better indicator since it focuses on the new cases and divides that number by the average population that is at risk at that certain time. It would be better at indicating the risk for women of that specific age group. When estimating the number of surgeons to treat breast cancer a prevalence proportion would be a better indicator. Because a prevalence proportion focuses on all cases and not just new cases, it can measure the ratio of how many surgeons will be needed to treat all people vs just new cases.

This includes showing all calculations and explaining why you selected a specific answer for each multiple choice question (i.e. donât just circle the correct answer). I am looking to see how you got the answer, not just that you have the correct answer.

Below is data from the United States Cancer Statistics about the number of news cases of lung cancer in males in the U.S. for 2011 for ages 30 and older.

Table 1: U.S. Population Size and Incidence Cases of Lung Cancer in Males for 2011

Age (Years)	U.S. Male Population	White Population	White Incidence Cases	Black Population	Black Incidence Cases
30-34	10,181,564	7,950,924	88	1,383,650	22
35-39	9,666,162	7,557,263	212	1,271,897	23
40-44	10,363,126	8,259,215	643	1,324,847	132
45-49	10,856,131	8,766,225	2,032	1,373,346	444
50-54	10,976,172	9,004,383	5,128	1,329,551	1,148
55-59	9,733,849	8,101,629	8,607	1,091,030	1,687
60-64	8,466,308	7,183,960	12,340	845,362	2,067
65-69	6,014,777	5,178,255	15,792	539,796	2,077
70-74	4,360,942	3,769,569	16,011	376,129	1,864
75-79	3,204,196	2,807,216	14,319	255,221	1,426
80-84	2,319,839	2,078,071	11,284	154,155	883
85+	1,873,942	1,688,433	7,616	117,267	545
Total	88,017,008	72,345,143	94,072	10,062,251	12,318

3. What is the age-specific incidence rate for lung cancer in white men age 75-79 for 2011?(1 pt)

0.005 per 1000

1.3 per 1000

1.2 per 1000

5.1 per 1000

5.6 per 1000

F. Cannot be calculated from the given information

4. What is the age-specific incidence rate for lung cancer in black men age 75-79 for 2011? (1 pt)

0.005 per 1000

1.3 per 1000

1.2 per 1000

5.1 per 1000

5.6 per 1000

F. Cannot be calculated from the given information

Questions 5 through 7 are based on the information below:

Using the information in Table 1, researchers calculated the crude incidence rates and age-adjusted incidence rates (via the direct method) for both groups.

Table 2: Crude incidence rates and age-adjusted incidence rates for white and black males

White Males		Black Males
Crude Incidence Rate	Age-adjusted Incidence Rate	Crude Incidence Rate	Age-adjusted Incidence Rate
1.3 per 1000	1.2 per 1000	1.2 per 1000	1.5 per 1000

5. True or False, there is likely a difference in the age composition between the white and black males. Explain your answer

6. Based on the information in Table 2, it was reported that there was an increased risk of lung cancer in black males in 2011. (1 pt)

The conclusion is:

Correct, the age-adjusted rate is higher in black males compared to white males

Correct, because both the crude and age-adjusted rates are higher in black males compared to white males

Incorrect, because the incidence rate for white males is actually higher than the incidence rate for black males

7. What type of age-adjusted rate was calculated in table 2? How does it differ from the age-adjusted rate in question 5 in the in-class exercise for age-adjustments? Hint: See slide title: Adjustments for Other Measures of Disease Frequency in the lecture title Adjusted Rates (1 pt)

Question 8 is based on the information given below:

Cause-specific mortality rates for men in 2010 in the U.S. from various types of cancers are shown in the table below:

Cause-Specific Mortality Rates

(per 100,000 Men)

Location of the Cancer

in the Body White Asian

Pancreas 13.2 5.7

Prostate 19.1 2.5

Lung 62.3 18.5

Skin 4.9 0.3

8. The inference that White men in the U.S. are at higher risk of death due to cancer of the pancreas, prostate, lung, and skin compared to Asian men in the U.S. is

A. correct

B. incorrect because of failure to determine cause-specific mortality rates

incorrect because proportionate mortality alone does not give an estimate of risk

D. incorrect because of failure to adjust for differences in the age composition of the two populations

E. incorrect because counts were used when cause-specific mortality rates were needed

9. In January 1996, a team of epidemiologists identified a sample of 4,500 men, 65-74 years of age, for a study of prostate cancer. Tests indicated that 315 of the men already had prostate cancer and, therefore, were not at risk. The rest of the men were followed prospectively for five years to determine the incidence rate of prostate cancer in the sample. By the end of the five years of follow-up 156 of the men had developed prostate cancer. What is the incidence rate of prostate cancer in this group?

10. An epidemiologic investigation that started on January 1, 2011, identified a population of 1,000 individuals. At the start of the study 4 were found to have the disease. During the year of study, 6 new cases were found; thus a total of 10 cases were identified. Among those 10 cases, 6 deaths occurred during the year. What was the prevalence of the disease during the 1-year study?

pinkhornet564

1. The risk of acquiring disease is measured by the

a. Incidence rate

b. Incidence rate times the average duration of the disease

c. Incidence rate divided by the prevalence rate

d. Prevalence rate

e. Prevalence rate times the average duration of the disease

2. The strength of an association between a factor and a disease is best measure by .

a. Incubation rate

b. Incidence of the disease in the total population

c. Prevalence of the factor

d. Attributable risk

e. Relative risk

3. Case fatality rate for a given disease refers to

a. The crude mortality rate per 100,000 population

b. Cause-specific mortality rate due to the disease

c. A fatal outcome of any disease

d. The percentage of deaths among cases of the disease

e. The proportion of deaths due to the disease among all deaths from all causes

4. An investigator is interested in etiology of neonatal jaundice. To study this condition, he selected 100 children who were diagnosed with this condition and 100 children born in the same period and in the same hospital who did not have a diagnosis of neonatal jaundice. He then reviewed the obstetrical and delivery records of their mothers to determine various prenatal and perinatal exposures. This is an example of a(n):

a. Cross-sectional study

b. Case-control study

c. Cohort study

d. Clinical trial

e. Experiment

5. Which of the following statements describes the major advantages of a randomized clinical trial?

a. It avoids observer bias

b. It lends itself to ethical justification

c. It yields results replicable in other patients

d. It rules out self-selection of participants to the different treatment groups

d. It enrolls representative patients

6. A survey conducted in England revealed that of 224 families in which there had been a known case of poliomyelitis, 56 maintained parakeets as a family pet. In another British survey, 30 out of 99 poliomyelitis patients questioned kept parakeets. The inference that there is some relationship between the presence of a parakeet in a household and the occurrence of poliomyelitis among household members is

a. Correct b.

Incorrect because of failure to distinguish between incidence and prevalence

c. Incorrect because a proportionate ratio is used when a rate is required to support the inference

d. Incorrect because a failure to recognize a possible cohort phenomenon

e. Incorrect because there is no control or comparison group.

7. An investigator determines the correlation coefficient between triglyceride levels and degree of atherosclerosis in sampled blood vessels to be +1.67. On the basis of this you would conclude that:

a. Triglyceride level is a good predictor of atherosclerosis

b. Triglyceride level is not a good predictor of atherosclerosis

c. High triglyceride levels cause atherosclerosis

d. Atherosclerosis cause high triglyceride levels

e. The investigator has incorrectly determined the correlation coefficient

8. A screening test of known sensitivity and specificity is applied to two populations. The prevalence of the disease being screened for is 10% in population A and is 1% in population B. Which of the following is true?

a. The percent of all negative tests that have false-negative results is lower in population A than in population B.

b. Specificity is lower in population A than in population B.

c. Reliability is higher in population A than in population B.

d. The percent of all positive tests that have false-positive results is lower in population A than in population B.

e. Specificity is higher in population A than in population B.

9. Serum cholesterol levels are obtained for four healthy men. The probability that all will fall below the 10th percentile of the distribution of cholesterol for healthy males is:

a. 0.4

b. 1 â (0.1)4

c. (0.1)4

d. (0.9)4

e. Cannot be determined from these data

10. In a diabetes screening program, the screening level for a positive blood sugar level in test 1 is set at 160 mg/dl, and in test 2 at 130 mg/dl. The sensitivity is:

a. Greater in test 1

b. Greater in test 2

c. Equal in test 1 and 2

d. Dependent on the size of the population being evaluated

PHRM3031 Lecture Notes - Lecture 5: Cohort Study, Confounding, Relative Risk

Document Summary

Get access

Related Documents

PHRM3031 Lecture 4: L4 - Randomised Controlled Trials 2

PHRM3031 Lecture Notes - Lecture 7: Systematic Review, Troponin

PCL102H1 Lecture Notes - Lecture 11: Comparative Genomic Hybridization, Biomarker, Drug Discovery

Related Questions