Health Medical Homework Help

Part A. Bias

QA1: A study to assess the association of diabetes and lifetime smoking habits compared a group of hospitalized individuals with diabetes (cases) with a group of volunteer individuals without diabetes (controls) who were full-time employees of the same hospital where the cases were identified. Interviews with the cases took longer since the interviewers wanted to be sure to probe for details about their risk behaviors. The results from this study reported, for the first time in the literature, a strong association between diabetes and smoking.

1. What specific type(s) of bias may be present (list at least 3 types of bias)? Please explain why you suspect each type of bias in 1-2 sentences.

1. The magnitude of this association is likely to be either over- or underestimated. Which do you think is the case, and what makes you think so?

QA2: A case-control study was conducted to assess the association of diet and ulcers. Newly diagnosed individuals with ulcers (cases) were compared with a random sample of individuals without ulcers (controls) in regard to their diet for the previous 2 years.

1. Which specific type of bias is most likely to affect the described study? Please explain your answer.

1. How could the study be better designed or conducted to reduce this bias?

QA3: Match the following issues with their type of bias (selection or information and the specific type).

1. In a randomized trial of the impact of physical activity on cognition those in the physical activity intervention group dropped out more than those in the control group.
   1. Selection or Information bias?
   2. Type of bias?
2. In a trial of mammogram screening, participants had the choice of being either: 1) randomized to personalized timing of screenings or the standard screening timeline OR 2) allowed to pick whether to join the personalized timing of screenings or the standard screening timeline.
   1. Selection or Information bias?
   2. Type of bias?
3. In a case control study of advanced stage Alzheimer’s disease, control participants were asked about their history of dietary fat intake, because cases had advanced Alzheimer’s disease a family member was instead asked the questions about the patient.
   1. Selection or Information bias?
   2. Type of bias?

Part B. Confounding

QB1: Many studies have been performed to look at the association of pesticides and Parkinson’s disease. When stratified by sex, here are the results of 3 different cohort studies. Please label whether the results appear that sex is a confounder, effect modifier, or neither.

	Crude RR	RR in Males	RR in Females	Confounder, effect modifier, or neither?
Ascherio et al. (2006)	5.63	5.3	1.01
Baldi et al. (2003)	1.72	1.73	1.70
Li et al. (2009)	2.57	0.99	1.01

QB2: In the study by Ascherio et al, 2006, are pesticides associated with a higher risk of Parkinson’s disease? Which RR(s) provide(s) you with this information?

QB3: Please interpret the association (Hint: this one is tricky!!)

QB4: In the study by Baldi et al, are pesticides associated with a higher risk of Parkinson’s disease? Which RR(s) provide(s) you with this information?

QB5: Please interpret the association.

QB6: In the study of Li et al, are pesticides associated with a higher risk of Parkinson’s disease? Which RR(s) provide(s) you with this information?

QB7:

In the above figure, is artery thickening representing a confounder to the relationship between High Cholesterol and Myocardial infarction? Please explain why or why not.