PHRM3031 Lecture Notes - Lecture 11: Relative Risk

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goldfox889

10 Aug 2018

School

Department

Pharmacy

Course

PHRM3031

Professor

Adam La Caze

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Document Summary

Ic incidence of the endpoint in the control group (%) It incidence of the endpoint in the intervention group (%) Relative risk ratio (rr) it / ic. Absolute risk reduction (arr) ic - it. Number needed to treat (nnt) 100 / arr. Incidence density = number of new cases / number of person years at risk of exposure. Ie incidence of the disease in the exposed group. Ine incidence of the disease in the non-exposed group. No (false neg. ) d (a+c) (b+d) c (false pos. )

Related Questions

Compute the Person-Years of smoking exposure using the tablebelow. (Hint: add the years at risk of throat cancer (TC) â seeexamples).
Once they develop TC they are no longer at risk and their yearsin the study canât be counted.
Add each personâs years of exposure in the right column andenter the value in the box next to âTotal P-Y at Risk of ThroatCancerâ.
Then count the P-Y at risk for the Current/Former Smokers(exposed) and the P-Y at risk for the Never-Smokers (notexposed)
Using the Person-Years for each exposure group as thedenominator and the number of TC recorded for each exposure group;compute the Incidence Density for TC risk in current/former smokers(exposed) (ID_E) & compute the incidence density forTC risk in never smokers (not exposed) (ID_NE).
The compute the Incidence Density Ratio (also call RR), dividethe ID_Eby the ID_NE. This value is interpretedthe same as the Relative Risk.

		Years in the Study at Risk of Developing ThroatCancer								Years at Risk
Person	Smoker	1	2	3	4	5	6	7	8	Years at Risk
A	Yes	at risk	at risk	TC	No longer at risk of throat cancer					2
B	No	at risk	at risk	at risk	at risk	at risk	at risk	at risk	at risk	8
C	No
D	Yes						TC
E	Yes				TC
F	No
G	No					TC
H	No								TC
I	Yes		TC
J	Yes							TC
	Total P-Y at Risk of Throat Cancer

Sum the Person-Years of Exposure for each exposure group? (1point)

Former/Current Smoker (1/2 point)

Never Smoker(1/2 point)

How many of the exposed & not exposed participantsdeveloped throat cancer (1 point)?

Former/Current Smoker (1/2point):

Never Smoker(1/2point):

What is the Incidence Density for the exposed (ID_E)and non-exposed (ID_NE) groups? (1 point)

Former/Current Smoker (1/2point):

Never Smoker (1/2 point):

Compute the Incidence Density Ratio (IDR). Is the IDRprotective or hazardous? (1 point).

10. Using the interpretation for Relative Risk onpage 120 of your text, interpret the meaning of the IncidenceDensity Ratio (1 pt):

rubyjellyfish692

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

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

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

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

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

Part II 1.The California Occupational Mortality study data set was employed to assess mortality data for the years 1979-1981. A 2% sample of employed persons from the 1980 census of California was used. It contains the occupation of each person who had died. This study, like any occupation-based study, is restricted to the work life span as far as age of subjects is concerned. This study used ages 16-64 years. Certain persons, because of their source of work, were excluded as subjects: homemakers, retired persons, students, disabled, military personnel, etc. Only main-stream-type employment was used in this study to establish occupations at risk for heavy alcohol drinking. Using the Table below, answer the following:

1.What occupations are most vulnerable to acquiring cirrhosis of the liver from heavy drinking?

2.List several of the occupations identified by the research studies that are more vulnerable to alcohol-induced, cirrhosis related deaths and that have the highest mortality rates.

3. What are possible confounding variables for the research in occupations and heavy drinking that lead to fatal diseases?

4. Based on available research data, develop and construct a web of causation along with the appropriate decision trees for occupational group-related alcohol deaths. Table. Alcohol Related Deaths in California, 1979-1981 Cirrhosis 5.5% Digestive organ cancers 5.7% Injuries 13.7% Suicide and homicide 5.% All other causes 64.9%

Zika and microcephaly Since May 2015, Brazil has experienced a significant outbreak of Zika virus. In recent years, Brazilian officials reported an increase in the number of babies born with microcephaly.

1. Briefly describe what we know and what we do not know about Zika virus.

2. What has been done and what should be done to prevent Zika virus epidemic in US and world-wide?

PHRM3031 Lecture Notes - Lecture 11: Relative Risk

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