Reference no: EM133122899

COMH 7047 Health Measurement - University of The Witwatersrand

QUESTION 1

Scenario
In England and Wales there was an increase in the number of deaths attributed to cancer of the lung in the first half of the 20th century. For example, in the quarter of a century between 1922 and 1947 the annual number of deaths recorded increased from 612 to 9,287, or roughly fifteen-fold. This remarkable increase was far out of proportion to the increase of population - both in total and, particularly, in its older age groups.

Two main causes were put forward: 1) general atmospheric pollution from the exhaust fumes of cars, from the surface dust of tarred roads, and from gas-works, industrial plants, and coal fires, and 2) the smoking of tobacco. Some characteristics of the former had become more prevalent in the last 50 years, and the smoking of cigarettes had greatly increased. Muller (1939) reported that only 3 out of 86 male patients with cancer of the lung were non-smokers, while 56 were heavy smokers, and, in contrast, among 86 healthy men of the same age groups there were 14 non-smokers and only 31 heavy smokers. There were similar reports from other countries.

A case-control study was conducted: 649 males and 60 females with lung cancer from 20 hospitals were matched to equal number of control patients (same age + sex) admitted to the same hospital with a disease other than cancer. A detailed smoking history was obtained from participants. Assume that the study was well-conducted and results were not judged to be due to bias or confounding. The following results were obtained:

Questions

1a) Comment on the use of counts to comment on the magnitude of disease in the first paragraph.

1b) Explain how the percentages in Table IV were calculated.

1c) In your own words, describe the case-control study design based on this study.

1d) Explain why you think the researchers used matching in this study.

f) Based on the information presented in this study

fi. Assess the association between smoking and lung cancer using the Bradford-Hill criteria for judging whether an association is causal. Use only the information provided in the scenario.

fii. What other four studies or information would you like to see in order to help you in your assessment?

fiii. In terms of causal relationships, is smoking

a) a necessary cause and/or

b) a sufficient cause of lung cancer? Explain your answer.

QUESTION 2

Residents of a community in the United States were asked to participate in a study to determine whether cigarette smoking was associated with age-related maculopathy (ARM). At a baseline examination, participants were asked to report their smoking habits. After 5 years, participants had an examination to determine whether they had developed age-related maculopathy. Table 1presents the number of cases of age-related maculopathy in the study measured at the follow-up examination among the 1682 male participants, aged 43-86 years, who did not have age-related maculopathy (ARM) at the baseline examination.

Table 1: Cases of age-related maculopathy by selected exposures, Flesher Bay, United States

2a) What is the study design? State a reason to support your answer.

2b) Does this study show any association between smoking and maculopathy? Explain your answer. Show all formulae.

2c) In Table 1, the data for alcohol drinkers and non-alcohol drinkers were presented separately. What was the investigator trying to assess?

2d) Briefly state the conclusion(s) that did the investigator could have drawn from the results in (2c) above.

QUESTION 3

In a recent study of dental erosion in 5-year old children, 2020 healthy school going children were selected for study. The investigators recorded the erosion level on their maxillary deciduous incisors and whether or not their communities used fluoridated water. The results are summarised in the table below.

3a) What is the incidence of erosion of the five years for the two groups of children? (Assume that the children's teeth were free of erosion at birth.)

3b) What is the incidence rate difference between the fluoridated areas and non-flu0ridated areas? Explain your answer.

3c) What is the relative risk for those in the non-flu0ridated group given that the non-fluoridated group are the exposed children? Interpret your answer.

QUESTION 4

In Country X, the age expectancy of a child aged 2 is 88 years. Last year, 100 000 children aged 2 years were sick for 2 weeks and 5% of them died. The disability weight of the disease is 0.5%.

4a) Using the information provided above, calculate the DALYs per 1000 children.

4b) Interpret the results obtained in (5a) above.

QUESTION 5

Find and read the paper cited below:

Themba Mzembe, Richard Lessells, Aaron S Karat, Safiyya Randera-Rees, Anita Edwards, Palwasha Khan, Andrew Tomita, Frank Tanser, Kathy Baisley, Alison D Grant, Prevalence and Risk Factors for Mycobacterium tuberculosis Infection Among Adolescents in Rural South Africa, Open Forum Infectious Diseases, Volume 8, Issue 1, January 2021, ofaa520,

Answer the questions that follow.

5a) State the rationale/reason, hypothesis and objective(s) of the study.

5b) State the study design. Explain your selection.

5c) What was the target population?

5d) Describe the study population comprehensively.

5e) Name the sampling method and explain the reason for using this sampling approach?

5f) Describe the final sample(s) used for the analyses.

5i) What was the outcome and how was it measured?

5j) What potential errors were prevented by limiting analysis to the final sample(s)?

5k) State the main conclusions made by the authors. Do you think these conclusion were justified?

5l) What two main study limitations presented in the paper.