- Paper 1: Interior Surface Materials and Asthma in Adults: A Population-based Incident
Case-Control Study
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 materials. As a physician, you are curious to know if various manmade synthetic indoor materials (carpets, plastic flooring, 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.
(a) From this information, what is the Population, the Exposure, and the Outcome? [2 marks]
(b) What study design would you choose to study this question? Why? [3 marks]
(c) Read the highlighted box on page 2 of Paper 1. Do you think the study identifies a representative group of cases from the population? Are the cases a special group of patients (either more ill or less ill than all cases in the community)?[5]
(d) Do the authors provide clear criteria for how they defined a \case” of asthma? [3 marks]
(e) 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]
(f) 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 in controls?[5mark]
(g) 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]
(h) Do you think that cases would remember exposure details more or better than the controls in this study? Explain [5 marks]
(i) 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]
- 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
(a) What study design did the investigators use?[3 marks]
(b) How does this study design differ from the design of the _first study we evaluated? [3 marks]
(c) 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 shortcomings of the database they used to identify participants?[2 marks]
(d) 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]
(e) Would you say that the study sample is clearly representative of the target population?[5 marks]
