Final answer:
To determine the effectiveness of diphenhydramine versus acetaminophen in the prevention of aseptic meningitis after IV globulin infusion, a randomized-sequenced double blind, placebo-controlled crossover clinical study is most appropriate.
Step-by-step explanation:
The most appropriate type of research study to determine if premedication with diphenhydramine is more effective than acetaminophen to reduce the incidence of aseptic meningitis after IV globulin infusion is a randomized-sequenced double blind, placebo-controlled crossover clinical study. This type of study design allows for the comparison of two or more treatments, or a treatment and a placebo, within the same patient group. Each participant receives the treatments in a sequential order, and neither the participants nor the researchers know which treatment is being administered at any given time (double blind), which minimizes bias and maximizes the reliability of the results.
The cross-sectional study is not suitable for this scenario as it is designed to assess the prevalence of an outcome or exposure at a single point in time and cannot establish causal relationships. On the other hand, randomized controlled trials (RCTs) are considered the gold standard for evaluating the efficacy of interventions because they effectively control for confounding variables and provide high-quality evidence.