Clinical Trials using EHR Databases

Randomized Controlled Trials (RCT’s) are considered the gold standard for clinical trials, esp., when the effect of an intervention on a disease process is being measured. RCT’s allow the investigator to control for confounding factors, which can create a bias in observational studies. This aspect is crucial for a new intervention to be approved.

Observational studies, on the other hand, are generally retrospective, and prone to biases. These biases originate as the investigator may not have access to all the data, and/or cannot control for a particular variable in historical data. Furthermore, initial observational studies were not conducted well and did not control for confounding factors. As knowledge of the limitations of observational studies have become more apparent in recent years, researchers have looked for ways to eliminate these limitations. Newer observational studies are much better at controlling confounding variables. A recent article published in the Cochrane Methodology Review Group1 concluded that there was little difference between RCT’s and observational studies. Furthermore, there is now an international coalition of researchers that have released guidelines on conducting observational studies2.

Electronic medical databases allow researchers to conduct observational studies using the data captured at the point of care. When compared to RCT’s, there may be a discrepancy in data collection in the medical record because, 1) Busy clinicians may not enter accurate or complete data in the record, 2) Patients may be non-compliant and may not follow through with the intervention (e.g. Not take prescribed drugs). Well done RCT’s are generally not prone to these issues.

On the other hand, EHR’s capture more real world scenarios. The patient population in these databases may have different demographics, more co-morbid conditions, and may be on many other drugs. Using data gleaned from EHR’s, therefore, allows observational studies to better estimate the effect of an intervention in the real world.

Due to reasons mentioned above, it is very unlikely that observational studies conducted using data from EHR databases will substitute RCT’s. The controlled environment in which an RCT is conducted is crucial for approval of interventions (i.e. Drugs and devices). However, observational studies using data gleaned from EHR’s will be very useful to understand the real life impact of these interventions.


  1. Anglemyer, A., Horvath, H. T., & Bero, L. (2014). Healthcare outcomes assessed with observational study designs compared with those assessed in randomized trials. Cochrane Database Syst Rev, 4, MR000034. doi:10.1002/14651858.MR000034.pub2
  2. The PLOS Medicine Editors. (2014). Observational Studies: Getting Clear about Transparency. PLoS Med, 11(8), e1001711. doi:10.1371/journal.pmed.1001711