Case-Control Study: The Relationship Between the Harmful Substances and Asthma

People spend much of their life indoors, but little attention has been paid to the health effects of the materials used for flooring, walls, and other indoor decorative elements. As a physician, you are curious to know if various human-made synthetic indoor materials (carpets, plastic tile, etc.) are associated with a higher risk of asthma in adults in the general population and if any studies have been done to assess this association.

From this information, what is the Population, the Exposure, and the Outcome? [2 marks]

The population comprised of randomly selected adults aged between 21-63years old staying in South Finland. They consist of 521 adults with new Asthma condition, as well as the control population of 932 adults satisfying the eligibility terms.

The exposure to some harmful compounds that bring about adverse immunological reactions in the airways. Outcome: resulting in a rise in the risk of bronchial hyperresponsiveness as well as asthma.

What study design would you choose to study this question? Why? [3 marks]

The case-control study design in which I will start with the outcomes and I will not have to pursue the people during the study. It is the best as it involves the interrogation of the cases or even the checking of their records to approve the various experiences they have gone through as this will help in the determination of the relationship that exists between the exposures to harmful substances and asthma.

Read the highlighted box on page 2 of Paper 1. Do you think the study identifies a representative group of cases from the population?

It identifies the representative group of the cases from the population because it checks for a team that has the eligibility criteria for the Asthmatic conditions and relates it to the other control group.

Are the cases a select group of patients (either iller or less ill than all cases in the community)?[5]

The team is unique because it only represents the people who are less harmful as seen by them having asthma-like conditions.

Do the authors provide clear criteria for how they defined a \case" of asthma? [3 marks]

They offer a standards on the way they represented a case in each case. For instance, they grouped the clients according to their health conditions, and it is from this that the group made sure that they only take in a group of qualified individuals to serve as the case.

Now read highlighted \Selection of controls" on page 744. Do you think there could be any selection bias from the way they recruited controls? [3 marks]

I believe that there was bias such that the group that was selected for the study was only those who were technologically advantaged and thus a group of respondents who could not get the letters or the calls were left out and therefore beneficial information might have been left out.

Read the highlighted section of \Exposure assessment" on page 744. Note that the questionnaire asked about each exposure type separately (carpet, plastic, etc.), even though it reads as if they combined some exposures. Was the \exposure" level determined in the same manner in cases and controls?[5mark]

It was decided using the same way. First, the identical questionnaires were used for all the conditions in different areas. The options of responses given to the clients comprised of a yes or no answer. This implies that the exposure levels were being determined in the same manner and using the same type of assessment criteria, which could have given biased information because the identical questionnaires may not be helpful in mining sufficient information for the study.

Describe what could happen if they inspected the cases houses to identify materials in the home and only administered the questionnaire only to the controls? [2 marks]

This would have increased the efficiency or accuracy of the results they found since they will determine for themselves the type of information about the materials in the house and link them to the conditions of the participants.

Do you think that cases would remember exposure details more or better than the controls in this study? Explain [5 marks]

The facts have higher chances of retaining the exposure details better than the controls being used in the study. The main reason being that they have been in the condition and they know that their requirements are as a result of specific materials in their houses. On the other hand, the controls could have less information since they only no idea of what their conditions are about.

Using data in the highlighted box in Table 2 on page 745 of the article handout, calculate and interpret the odds ratio for the two levels of plastic flooring, compared to the No plastic flooring group [5 marks]

From the analysis the number of respondents infected with asthma in the no-plastic flooring in the home environment is 130. Those infected in a flooring area of less than half of the surface area is 118 and those affected in a flooring area greater than half is 273. From the odds ratio we can see that the ratio of those affected in less than half flooring area is less than those affected in greater than half flooring area. This implies that those living in more than half plastic flooring are likely to be infected by asthma that those living in less that half. This might be due to extra coldness attracted by plastic floors.

2. Paper 2: A study was designed to measure the burden of COPD in Salzburg, Austria

The investigators identified a random sample of the inhabitants of Salzburg over the age of 40 and invited them to attend the study clinic where they completed a questionnaire and had pulmonary function tests (PFTs) performed

What study design did the investigators use?[3 marks]

They used the systematic review study. It entails of critical evaluation of all the studies that deal with certain medical issues. For instance, there was a survey in which they quantitative collected the information to use for the research.

How does this study design differ from the design of the _first study we evaluated? [3 marks]

It varies in that the first one entailed the use of case-control research while the second one involves the use of systematic review research study. It also c onsists of the use of surveys to pool the data while the first one entails the use of control group to determine the relationships.

Read the highlighted box A (Study Population) on page 30 of Paper 2 What are the shortcomings of the database they used to identify participants? What are the failures of the database they used to determine participants? [2 marks]

The database technique only relies on the participant's knowledge in using of various technological methods such as letters and phone calls which implies they might have missed vital information.

Look at Figure 1 on page 31 of Paper 2. What percent of people the investigators approached (called the target population here) actually joined the study? [4 mark]

57.20% of the target population joined the study. This can be seen by the number of people who finally participated in the study, 1258, and the entire population of 2200people.

(e) Would you say that the study sample is clearly representative of the target population? [5 marks]

It is not a true representation of the target population because of the low percentage turnout from the entire population. Most of them did not give valid information as shown by the large number of correspondents who did not qualify for the study.