Question

#11-16. For each study described, state whether it will experimental or observational. If observational, identify which type specifically (retrospective cohort, prospective cohort, case-control, cross-sectional, ecological). Briefly explain how you can tell.

• We plan to distribute a questionnaire to all UNLV faculty, students and staff ages 40 and 60. In that questionnaire, we will ask if they suffer from kidney disease, and if they take regular medications including BZDs. We than assess how many people with kidney disease take BZDs and how many people without KC take BZDs.

• We select a group of 1,000 middle-aged volunteers without kidney disease who are likely to suffer from insomnia/anxiety. We assign them randomly into two groups. Group 1 is told to live their lives as normal and take any meds proscribed by their doctor. Group 2 is told not to use BZDs for 2 years, and doctors prescribe Group 2 with natural alternatives to BZDs. After those 2 years, we follow them up and check to see who developed kidney disease in each group, and compare the groups.   

• We will get the age-adjusted incidence rates of kidney disease in 30 different countries and compare those with the rates of BZD consumption per capita (total usage in country/total population of that country). We will then check to see if there is a correlation between the BZD consumption and kidney disease.

• In 2010, we examined the medical records of 2,000 patients ages 53+ associated with Kaiser Permanente (large health care organization) who did NOT have kidney disease in 2005. Then, we look back in the records to see who took BZDs from 2000-2005. After that, we look to see who developed kidney disease from 2006 until 2008. We compared the rates of kidney disease among those who took the BZDs and those who didn’t.

• We plan to select a large healthy group of 4000 50-year old people from the general population and give them a questionnaire to fill out. One of the questions concerns the use of BZDs. We are going to follow them for 5 years and compare how many developed kidney disease among those who said yes to BZD consumption and among those who said no to BZD consumption.

• We will select 200 patients with kidney disease and 600 patients without kidney disease. We will then access their prescription records to see if they used BZDs regularly when they were aged 40-50 years of age.

Answer 1

1. Its an observational study prospective cohort type. The rationale behind is this that we are just observing the presence of risk factor to the people who are exposed to it. Here it comprises, patient with kidney disease who are taking benzodiazipenes or not. There is no active intervention required in this type of study.

2. This is an experimental study as subjects are assigned to two different groups and they receive different treatmens.

3. This is an observational study cross sectional type. This is so as we are accessing data from a specific population who have been exposed to the benzodiazepines and its possible relation to kidney disease.

4. This is an observational study retrospective cohort type. In this kind of study we go retrospectively ie go back in time and gather information regarding the specific drug and disease occurence. The event and outocme have already occured and information is assessed to ascertain its relationship.

5. this is an example of ecological study. here the study populations are assessed using risk modifying factors and their effect on outcomes. for eg here we are going to see what the effect of benzodiazepines has on kidney disease 5 years from now.

6. This is an observational study case control type. In this kind of study we go back retrospectively to compare patients who have a disease or outcome of interest (kidney disease) with patients who do not have the disease or outcome (do not have kidney disease). Then we access the association of risk factor between cases and controls.