Question 3: A researcher wants to investigate the relationship between intravenous drug use and staph infection. The researcher proposes a study that would enroll 1,000 young adults. Each participant will be asked whether or not they have every used intravenous drugs and, if so, for how many years. Participants will be followed over time to determine whether or not they develop staff infection. The planned statistical analysis is to calculate the incidence density for those with a history of IV drug use and for those without a history of IV drug use. The incidence densities will be used to calculate a risk ratio.

a)What type of study design has the researcher proposed?

b)The institutional review board reviewing the proposed study is concerned that participants may not want to admit to using intravenous drug use. How could this bias the results of the study? Would make an association between IV drug use and staph infection look stronger or weaker?

c)The institutional review board is also concerned about loss to follow-up, especially among intravenous drug users. How could loss to follow-up bias the results of the study? Would it make the association between IV drug use and staph infection look stronger or weaker?

d)In the United States, the incidence of staph infection in the general population is approximately 40 cases per 100,000 person years. The institutional review board is concerned that very few of the study participants are likely to develop staph infection. Why would this be a problem?

e)Due to their concerns, the institutional review board has encouraged the researchers to consider using a different study design. If you were to suggest a different study design, what type would you suggest and why?