Sean Hennessy, PharmD, PhD

faculty photo
Professor of Epidemiology in Biostatistics and Epidemiology
Department: Biostatistics and Epidemiology
Graduate Group Affiliations

Contact information
University of Pennsylvania
423 Guardian Drive
803 Blockley Hall
Philadelphia, PA 19104-6021
Office: 215-898-9112
Fax: 215-573-5315
BS (Pharmacy)
Philadelphia College of Pharmacy and Science, 1989.
PharmD (Clinical Pharmacy)
Philadelphia College of Pharmacy and Science, 1990.
MSCE (Clinical Epidemiology)
University of Pennsylvania School of Medicine, 1996.
PhD (Epidemiology with Biostatistics minor)
University of Pennsylvania, 2002.
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Description of Research Expertise

Dr. Hennessy conducts research in the field of pharmacoepidemiology, which is the study of the health effects of drugs and other medical products in populations. His team identified a survival benefit of potassium supplementation in users of loop diuretics, and studied serious health consequences of drug-drug interactions involving high-risk drugs including anticoagulants, antidiabetic agents and antiplatelet agents. His research has produced crucial knowledge about the cardiovascular safety of many widely-used drugs for mental health conditions in including ADHD, depression, and schizophrenia. He also evaluated an early approach to using medical insurance data to improve prescribing, finding it ineffective despite its federal mandate. This contributed to the omission of a requirement for drug utilization review programs in Medicare Part D. He co-led a pair of studies demonstrating the effectiveness and safety of the SA14-14-2 vaccine for Japanese encephalitis (JE), which subsequently led to the immunization of millions of children per year in populous countries including Cambodia, India, Malaysia, Nepal, Sri Lanka, and Thailand. Use of that vaccine has been credited with reducing the incidence of JE. He co-developed the trend-in-trend research design for studying the effects of rapidly increasing or declining exposures. He was the senior author of one of two citizen petitions to the US Food and Drug Administration that led to re-labeling of metformin, the best-proven oral drug for diabetes, to permit its use in persons with mild to moderate renal insufficiency.

Selected Publications

Hennessy S, Leonard CE, Gagne JJ, Flory JH, Han X, Brensinger CM, Bilker WB.: Pharmacoepidemiologic methods for studying the health effects of drug-drug interactions (DDIs). Clinical Pharmacology and Therapeutics 99: 92-100, 2016.

Hennessy S, Strom BL: Improving post-approval drug safety surveillance: Getting better information sooner. Annual Review of Pharmacology and Toxicology 55: 13.1-13.13, 2015.

Leonard CE, Bilker WB, Brensinger CM, Han X, Flory JH, Flockhart DA, Gagne JJ, Cardillo S, Hennessy S: Severe hypoglycemia in users of sulfonylurea antidiabetic agents and antihyperlipidemics. Clinical Pharmacology and Therapeutics 99: 538-47, 2016

Flory JH, Hennessy S: Metformin use is substantially reduced in mild-moderate renal impairment. JAMA Internal Medicine 174, 2015 (doi:10.1001/jamainternmed.2014.6936).

Leonard CE, Bilker WB, Brensinger CM, Flockhart DA, Freeman CP, Kasner SE, Kimmel SE, Hennessy S: Comparative risk of ischemic stroke among users of clopidogrel together with individual proton pump inhibitors. Stroke 46: 722-31, 2015.

Ioannides KLH, Mamtani M, Shofer FS, Small DS, Hennessy S, Abella BS, Scott KR: Medical students in the emergency department and patient length of stay. Journal of the American Medical Association 314: 2411-13, 2015

Ertefaie A, Small DS, Flory J, Hennessy S: A sensitivity analysis to assess bias in IV analyses due to selecting subjects based on treatment received. Epidemiology 2015 (DOI: 10.1097/EDE.0000000000000430).

Flory J, Haynes K, Leonard CE, Hennessy S: Proton pump inhibitors do not impair the effectiveness of metformin in diabetic patients. British Journal of Clinical Pharmacology 78: DOI: 10.1111/bcp.12506, 2014

Schelleman H, Bilker WB, Kimmel SE, Daniel GW, Newcomb C, Guevara JG, Cziraky MJ, Strom BL, Hennessy S: Methylphenidate and risk of serious cardiovascular events in adults. American Journal of Psychiatry 169: 178-85, 2012.

Hennessy S: Potentially remediable features of the medication-use environment in the United States. American Journal of Health-System Pharmacy 57: 543-548, March 15 2000.

Liu ZL, Hennessy S, Strom BL, Tsai TF, Wan CM, Tang SC, Xiang CF, Bilker WB, Pan XP, Yao YJ, Xu ZW, Halstead SB: Short-term safety of live attenuated Japanese encephalitis vaccine (SA14-14-2): results of a randomized trial with 26,239 subjects. Journal of Infectious Diseases 176: 1366-1369, 1997.

Hennessy S, Liu Z, Tsai TF, Strom BL, Wan CM, Liu HL, Wu TX, Yu HJ, Liu QM, Karabatsos N, Bilker WB, Halstead SB: Effectiveness of live-attenuated Japanese encephalitis vaccine (SA14-14-2): a case-control study. Lancet 347: 1583-1586, 1996.

Hennessy S, Berlin JA, Kinman JL, Margolis DJ, Marcus S, Strom BL: Risk of venous thromboembolism from oral contraceptives containing gestodene and desogestrel versus levonorgestrel: a meta-analysis and formal sensitivity analysis. Contraception 64: 125-133, 2001.

Hennessy S, Bilker WB, Berlin JA, Strom BL: Factors influencing the optimal control-to-case ratio in matched case-control studies. American Journal of Epidemiology 149: 195-197, 1999.

Hennessy S, Bilker WB, Weber A, Zhou L, Brensinger C, Wang Y, Strom BL: Retrospective drug utilization review, prescribing errors, and clinical outcomes. Journal of the American Medical Association 290: 1494-9, 2003.

Mansson R, Joffe M, Sun W, Hennessy S: On the estimation and use of propensity scores in case-control and case cohort studies. American Journal of Epidemiology 165: 1-8, 2007.

Hennessy S, Bilker WB, Weber A, Brensinger C, Strom BL: Retrospective drug utilization review, prescribing errors, and clinical outcomes. Journal of the American Medical Association 291: 185-186, 2004.

Schelleman H, Bilker WB, Brensinger CM, Han X, Kimmel SE, Hennessy S: Warfarin with fluoroquinolones, sulfonamides, or azole antifungals: interactions and the risk of hospitalization for gastrointestinal bleeding. Clinical Pharmacology and Therapeutics 84: 581-588, 2008.

Schelleman H, Bilker WB, Brensinger CM, Wan F, Yang Y, Hennessy S: Fibrate/statin initiation in warfarin users and gastrointestinal bleeding risk. American Journal of Medicine 123: 151-7, 2010.

Schelleman H, Brensinger CW, Bilker WB, Hennessy S: Antidepressant-warfarin interaction and associated gastrointestinal bleeding risk in a case-control study. PLoS ONE 6: e21447, 2011 Notes: doi:10.1371/journal.pone.0021447.

Hennessy S: When should we believe non-randomized studies of comparative effectiveness? Clinical Pharmacology and Therapeutics 90: 764-66, 2011.

Toh S, Reichman ME, Houstoun M, Ross Southworth M, Ding X, Hernandez FF, Levenson M, Li L, McCloskey C, Shoaibi A, Wu E, Zornberg G, Hennessy S: Comparative risk of angioedema associated with the use of drugs that target the renin-angiotensin-aldosterone system. Archives of Internal Medicine 172: 1582-1589, 2012.

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Last updated: 03/14/2017
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