Which measure is most appropriate for determining the strength of association between chlorhexidine exposures and Burkholderia cepacia complex infections?

• A. Relative Risk
• B. Odds Ratio
• C. Hazard Ratio
• D. Attributable Risk

Answer: (B)

In this scenario, the strength of the link between chlorhexidine exposure and Burkholderia cepacia complex infections is best measured using an odds ratio. When studying a rare infection outbreak, researchers often use a case-control design: they compare how often people with the infection were exposed to chlorhexidine versus how often people without the infection were exposed. The odds ratio directly compares these exposure odds between cases and controls, giving a clear sense of how much more likely exposure is among those with the infection. It doesn’t require knowing the actual incidence of infection in a population, which is hard to obtain for rare outcomes.

Relative risk would require data from a defined cohort with observed incidence in the exposed and unexposed groups. Hazard ratio is used for time-to-event analyses, not a straightforward case-control exposure comparison. Attributable risk focuses on the excess risk due to exposure, not the strength of the association between exposure and infection. So the odds ratio best captures how strongly chlorhexidine exposure is associated with developing the infection.