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Vice Chair for Educational Programs, Department of Epidemiology
Stephan Ehrhardt

Departmental Affiliations

Clinical Trials and Evidence Synthesis

Stephan Ehrhardt, MD, DTMPH, MPH, designs and leads data coordination centers, managing complex, multicenter randomized clinical trials.

Contact Info

615 N. Wolfe Street, Room E6153

Research Interests

Randomized clinical trials; cohort studies; data coordinating centers; multicenter studies; network studies; research ethics

Experiences & Accomplishments
HAW Hamburg, Germany
Free University Berlin
Charite University Medicine

My research interests include clinical trial methodology, in particular the design, conduct, and analysis of randomized clinical trials (RCT). Specifically, I am involved in developing methods to estimate more precise treatment effects across subgroups of study participants. RCT generally focus on estimating the average treatment effect of an intervention across the study sample. We aim to use prognostic data to determine individual randomization probabilities to increase external validity of RCTs, allow for estimation of complex treatment heterogeneity, potentially improve outcomes in study participants in the control arm, and improve the acceptability of RCTs to study participants while minimizing the loss of power in estimating the average treatment effect.

I design, lead, and co-lead flexible and methods-driven Data Coordinating Centers (DCC) for large and complex multicenter clinical trials across a variety of content areas.

For example, ENRICH is a multicenter, cluster-randomized trial evaluating a new home visiting-based intervention to improve cardiovascular health (CVH) in pregnant people and their offspring. Poor CVH contributes greatly to maternal morbidity and mortality in the United States, and many families enrolled in home visiting are at risk for poor CVH.  Improving CVH requires focusing on CVH risk factors, 2-generation strategies addressing mothers and children, and greater use of settings where families already receive care.  The Johns Hopkins Early Intervention to Promote Cardiovascular Health of Mothers and Children (ENRICH) Resource and Coordinating Center (RCC) will generate rigorous, innovative, timely and actionable new knowledge to promote CVH and reduce CVH disparities in mothers and young children.

Another current project is the Clean Air 2 DCC. COPD is a leading cause of death and morbidity worldwide and is attributable to the aggregate burden of toxic gases and particles that individuals inhale during their lifetime. Particulate matter (PM) and nitrogen dioxide (NO2) are common pollutants in indoor environments where adults with COPD spend >90% of their time. In a Phase III multi-center randomized sham-controlled trial we are testing the effectiveness of an air cleaner intervention targeting indoor pollutants (PM and NO2) on quality of life and exacerbation risk reduction among former smokers with COPD (n~770) across multiple clinical practice locations.

Other areas of interest include neurology and gastroenterology. I have worked across a variety of settings in both high- and low-income countries and am experienced in leading multi-country research projects.

Methodologic issues in observational network studies and consortia are of great interest in addition to the interventional work.

My research portfolio includes research ethics in multicenter studies.

Select Publications

Selected publications: *Student, staff, or junior faculty supervised or mentored

  • Ehrhardt S, Appel LJ, Meinert CL. Trends in National Institutes of Health Funding for Clinical Trials Registered in JAMA. 2015 Dec 15;314(23):2566-7. doi: 10.1001/jama.2015.12206.

  • Ervin AM, Taylor HA, Meinert CL, Ehrhardt S. RESEARCH ETHICS. Evidence gaps and ethical review of multicenter studies. Science. 2015 Nov 6;350(6261):632-3. doi: 10.1126/science.aac4872.

  • Barthel D*, Barkmann C, Ehrhardt S, Schoppen S*, Bindt C; International CDS Study Group. Screening for depression in pregnant women from Côte d?Ivoire and Ghana: Psychometric properties of the Patient Health Questionnaire-9. J Affect Disord. 2015 Nov 15;187:232-40. doi: 10.1016/j.jad.2015.06.042.

  • Thio CL, Guo N*, Xie C*, Nelson KE, Ehrhardt S. Global elimination of mother-to-child transmission of hepatitis B: revisiting the current strategy. Lancet Infect Dis. 2015 Aug;15(8):981-5. doi: 10.1016/S1473-3099(15)00158-9.

  • Ehrhardt S, Xie C*, Guo N*, Nelson K, Thio CL. Breastfeeding while taking lamivudine or tenofovir disoproxil fumarate: a review of the evidence. Clin Infect Dis. 2015 Jan 15;60(2):275-8. doi: 10.1093/cid/ciu798.

ENRICH multicenter, cluster randomized trial (
Clean Air 2 multicenter, randomized clinical trial (
NatPro multicenter, randomized clinical trial (
S-CitAD multicenter, randomized clinical trial (