In pharmacoepidemiology, cohort studies and case-control studies have been commonly used as research methods to examine causal relationship between exposures to medicines and occurrences of advance events. For both study designs, we could assume a common population at risk, in which cases are developed. A cohort study defines a research cohort within the population at risk and tries to investigate the research cohort directly, and a case-control study tries to investigate the research cohort partly by the control sampling. Assuming an underling research cohort, it becomes possible to understand cohort studies and case-control studies within an unified framework. We revisited several sampling methods to select controls in case-control studies and effect measures implied by the sampling methods. (Jpn J Pharmacoepidemiol 2013; 18(2): 95-111)

MHLW released a guideline for Risk Management Plan (RMP) in April 2012, in order to manage the risk of pharmaceutical products from the development stage towards post marketing period. The guideline suggests to determine Safety Specification and to develop Pharmacovigilance Plan (PVP) and Risk Minimization Plan aligned to the ICH E2E guideline. However, in some of the RMPs, which had been published online (as of August 2014), conventional (Special) Drug Use Results Surveys are planned as a “universal” PVP regardless of the impact, severity and characteristics of the risks. Our JPMA taskforce (Data Science Expert Committee) summarized report and published in August 2014. In this report, we explained how to evaluate safety events based on evidence level for safety specification and how to develop PVP. Also, we would like to propose KAIZEN activities for RMP improvement as follows:
1. In order to clarify the research question, rationale and evidence for safety specification should be evaluated carefully.
2. It is essential to be considered in advance how to collect and analyze the safety data for detecting safety specification during clinical development.
3. Safety profiles should be discussed thoroughly on DSUR development among stakeholders in order to clarify safety specification at NDA. Research questions for each different risk and missing information should be established according to PECO, which will flow into appropriate PVP planning.
4. Continuous PDCA cycling is critical for RMP. The first survey or research will bring you next research question (s).
We expect all stakeholders, including clinical development specialists in industry, regulatory authorities, and academia, to have better understating of RMP principle and to manage and implement it more appropriately in a scientific manner.