Research Techniques Made Simple: Databases for Clinical Research Katrina Abuabara, MD MA David Margolis, MD PhD University of Pennsylvania

What Is the Research Question? The usefulness and validity of databases depend on the research question Research questions are often framed around an exposure and an outcome – Exposure: environmental, medication, risk factor, or disease – Outcomes: onset of disease (incidence), presence of disease (prevalence), or severity of duration of a disease or symptom

Which Epidemiologic Study Design?

What Type of Electronic Database? Repurposed data: originally generated for purposes other than clinical research – Administrative claims data – Electronic medical record (EMR) data Ad hoc data: designed for a particular study, often prospective cohort or registry Hybrid data: Blends features of the prior two categories

What Type of Electronic Database?

Design of a New Patient Database Consider measures to optimize data collection, patient follow-up, data quality, and and data security Consider the generalizability of the results when selecting patients Consider whether to include a valid comparison group

Considerations for the Design of a New Registry or Database 1 1. PCORI Standards Committee (2013) The PCORI Methodology Report.

Potential Sources of Bias Bias is a systematic deviation of a study’s result from a true value – Information bias: systematic differences in the accuracy or completeness of data leading to differential misclassification of individuals – Selection bias: systematic differences in the probability of including subjects in the study (or being lost to follow-up) leading to spurious conclusions

Potential Sources of Imprecision Imprecision may arise from the study size or from the measurement of exposures, confounders, or outcomes Detailed chart review and physician query may be used to evaluate the validity of measurements Dermatologic outcomes are not often precisely measured in electronic databases