Reference no: EM133865290

Epidemiology and Statistics

Assessment Overview
This individual assessment is designed to evaluate your understanding of key concepts used in epidemiological investigation and their application in public health. It will assess your ability to distinguish different measures of disease frequency, their association with determinant factors, data sampling and validity, and their interpretation and application in real-world public health scenarios.

Scope of Assessment
The assessment covers content from Weeks 1 to 7, focusing on fundamental epidemiological principles, including:

Epidemiological Measures: Understanding measures of frequency, including cumulative incidence, incidence rate, and prevalence (point and period), as well as mortality, morbidity and case fatality rates, and data standardisation.

Measures of Association: Exploring the relationship between exposure factors and outcomes to calculated risk/rate ratios, odds ratios, impacts of association, and the interpretations of the measures

Epidemiological study designs: characterise different types of quantitative study designs both descriptive and analytical and their measures or associations.

Population data presentation and analysis: distribution of data into exposure and outcome groups, conduct appropriate data analysis, explain effects, and interpret the findings

Sampling process and data validity: Identify the sampling strategy, procedures and assess data validity and representativeness and generalisability of the study data.

QUESTION 1
Following reports of new cases of an infectious disease in a residential care facility within a regional community, the local health department undertook measures to monitor the emergence of additional cases among vulnerable residents. To evaluate the extent of the issue, a month-long study was conducted, involving all 150 residents of the facility. It is known that infection with this disease confers permanent immunity. All residents were present in the facility throughout the four-week study period, with attendance accounted for during scheduled health assessments. The chart (Figure 1.1) below illustrates the occurrence of the disease across the four-week period within the facility.

The remaining residents, not shown in the chart, were unaffected by the disease.

 

Using the disease occurrence chart in Figure 1.1, please answer the following questions.

At the start of the study (the start of week 1), the research team assessed the extent and severity of the infectious disease affecting residents in the residential care facility.

If researchers want to know how many residents were having the disease at day one of the study, which is the most appropriate measure of frequency for researchers to use here?

Calculate this measure of frequency and interpret your result

How many residents were at-risk of developing the disease at the beginning of the study period?

How many residents developed the disease during the study period?

Calculate the total person-days at risk for the study population, using whole days. Assume, no one else was added or dropped out

Using your results in part ‘d' and ‘e', please calculate the appropriate measure of the infectious disease and interpret your result? You should express your answer as cases per 100 person-week

Using disease occurrence chart in Figure 1.1, calculate the case fatality rate and interpret your result? Express your answer in percentage rate

How would you verify whether the current rate of occurrence of the disease is above the usual rate?

QUESTION 2
A study was performed to investigate the association between obesity and the occurrence of lower body joint conditions (e.g., osteoarthritis, joint pain) in adults aged 40-60 years. The study randomly selected 1,000 individuals from medical records and assessed obesity status over a 10-year period, and the occurrence of lower body joint conditions was evaluated at the end of this period. The study found that among the 288 obese participants (BMI ≥30), 183 developed lower body joint conditions, and among the 712 non-obese participants (BMI <30), 143 developed lower body joint conditions.

Based on the study findings, construct a 2 x 2 table for 1000 people showing the number of people that developed joint conditions in exposed group and number of people that developed joint conditions in non-exposed group over the study period. Label the exposure and outcome groups. Give your table a title in 15 words or less.

Title: ..................................................................................................................................................
Exposure Outcome
................................ ................................ Total
................................ ......... ......... .........
................................ ......... ......... .........
Total ......... ......... 1,000

What would be the appropriate measure of frequency in this study?

Calculate the appropriate measure of frequency (risk) of joint conditions for:

Those that were obese

Formula:
Calculation: workout

Those that were not obese

Formula:
Calculation: workout

For all joint conditions

Formula:
Calculation: workout

Calculate the appropriate measure of association and interpret your answer

Formula:
Calculation: workout
Interpretation:

Assuming a causal link, what percentage of the cases of joint conditions in those that are currently obese is due to their current obesity? Interpret your answer

Formula:
Calculation: workout
Interpretation:

QUESTION 3
Using the table provided, please classify each hypothetical study described below (i-v) according to:
Whether they are:
Cross-Sectional Study - Analytical
Ecological Study - Analytical
Cross-Sectional Study - Descriptive
Case-Control Study
Retrospective Cohort Study
Prospective Cohort Study
Longitudinal Study - Descriptive
Randomised Controlled Trial
Justify why the study is either a descriptive or an analytical study and justify why it is the selected study design, use less than 15 words.

Name the measure of frequency (point prevalence, period prevalence, cumulative incidence, incidence rate) or the measure of association {e.g., prevalence (rate) ratio, risk ratio, rate ratio, and odds ratio of exposure} appropriate for the study design. Some studies may have more than one possible measure, please list only one; also, do not use the term relative risk.

Study scenarios:
i During a disease outbreak of listeriosis in a small outback community, local public health officials conducted an investigation to identify the cause of the outbreak among the visitors to a local food festival. On interview, the investigative team found that 44 of diseased had eaten watermelon and 60 did not.
ii. Ageing Research Institute wanted to study the effectiveness of an improved medicated skin device for skin wrinkle treatment in 40-55 years women. They included 10 local skin clinics that agreed to participate in the program. From a list of 256 referred clients from the skin clinics, 100 clients met the eligibility criteria and consented to participate. They were randomly allocated to either the improved medicated skin device or a usual skin device and followed for 6-months period. None of the participants received any financial benefit from the study.

iii. The Public Health Nutrition unit of a local metropolitan city council wanted to examine the association between dietary habits and obesity among adult residents. The research team decided to send questionnaires to a randomly selected group of 100 adults residing in the city council area. They collected data on present dietary patterns, including the consumption of fruits, vegetables, and processed foods, health conditions as well as demographic features, to analyse the relationship between these variables.

iv. Researchers conducted a study to observe changes in cognitive health and identify patterns of cognitive decline among 500 adults aged 65 and above. The participants were followed for a period of 15 years, with assessments conducted every two years to monitor their cognitive health and physical activity levels.

v. A children health research team planned to look at the effect of long-term exposure to air pollution on the respiratory health in children. They randomly selected 1,000 children aged 5-15 years from randomly selected schools in Victoria and followed for a period of 10 years, with assessments conducted annually.

Please place your answers to Q3 in the table below (you can expand the table as required)

Question Study type
b. Reasons in less than 15 words 1 mark for analytical/descriptive, 1 mark study design c. Relevant measure of frequency or association

QUESTION 4
Post-Traumatic Stress Disorder (PTSD) is a psychological condition linked to personal mental stress or trauma experienced by the individual in the past. Literature suggests early-childhood stress could be a cause for developing PTSD later in the life. To investigate, researchers recruited 100 individuals aged between 25 and 45 years suffering from PTSD from a national mental health register and 150 individuals of the same age range free from PTSD living in the community. The research team obtained consent from all participants and interviewed about their early childhood experience before the age of 18 years. Participants mental stress was measured by the Perceived Stress Scale (PSS-10) for early-childhood psychological stress. The table below presents the study findings.

Table 4.1: Frequency of participants suffered from PTSD and their early-childhood stress

		PTSD
		yes	no
Early-childhood stress	yes	54	45
	no	46	105
Total		100	150

Name the measure of association that would be most appropriate to assess the data for an association between the early-childhood stress and PTSD.

Calculate the appropriate measure of association and interpret your result.

If investigators decide to recruit controls for the study from a hospital accident trauma ward instead of selecting non-PTSD control from general population, what type of bias would this introduce? Explain.

What public health implication conveyed by the study results? What preventative measures can be recommended to reduce the exposure to traumatic childhood experience, use a socio-ecological model to elaborate your response.

 

Public health implication:

Socio-ecological model:
Intrapersonal/individual factors:
Interpersonal factors:
Community factors:
Institutional and organisational factors:
Public policy factors:

QUESTION 5

Read the abstract below then answer the following questions:

Background: Night shift work is a common practice in healthcare settings, often necessary to provide continuous patient care. However, the disruption of circadian rhythms associated with night shifts may have adverse effects on health workers' sleep patterns, potentially leading to insomnia.

Objective: This study aims to investigate the prevalence and severity of insomnia among healthcare workers aged 35-65 who engage in night shift work.
Methods: Hospital emergency units in Melbourne that agreed to take part in the study were asked to mail invitation letters to all emergency doctors, nurses and paramedics aged 35-65 years who were rostered for dayshift and nightshift at least 7 days per months in the last 6 months period to take part in the study. Participants were asked to attend a sleep research clinic, within 20 kilometres of their residence, for clinical measurements of level of insomnia using the Insomnia Severity Index (ISI) and complete a questionnaire about their work schedules, sleep habits, and demographic information.

Of the 5,200 adults aged 35-65 years contacted, 1,248 volunteered to take part in the study. The participants were in paid employment and did not always work at home. Participants were followed up every 6 months. At 24 months follow-up, 640 had withdrawn from the study. The researchers had complete data from 608 participants.

Results: The findings revealed that 45% of night shift health workers reported moderate to severe insomnia, compared to 20% of their day shift counterparts. The prevalence of insomnia was significantly higher among those with irregular night shifts and longer shift durations. Factors such as age, gender, and years of experience were also analysed, with younger and less experienced workers showing higher rates of insomnia.

Conclusion: Night shift work is associated with a higher prevalence of insomnia among health workers. Interventions aimed at mitigating the impact of night shifts on sleep, such as optimising shift schedules and providing sleep hygiene education, are essential to improve the well-being and performance of health workers.

Identify the population of interest, sampling frame (source population), study sample, and study participants used.

What type of sampling method is being used? What is the disadvantage of using this type of sampling method.

In less than 150 words, please comment on the response rate. Why is this important?

Response rate:
Importance of response rate:

Please suggest factors which may undermine the representativeness of the study sample.