Core Outcome Measures in Effectiveness Trials

Development of a definition and core outcome set for studies in hyperemesis gravidarum

General Information

Nausea and vomiting are common in pregnancy (NVP): up to 80% of women suffer nausea, and up to 50% suffer vomiting. Hyperemesis gravidarum (HG) is less common, affecting 0.2-3.6% of pregnant women. Women with HG have extreme nausea and vomiting, and may lose weight, become dehydrated, and are frequently admitted to hospital. Some studies indicate HG may lead to adverse perinatal and long-term offspring outcome. There is no consensus on the exact criteria for HG or a minimum set of core outcomes to be reported in intervention studies on HG. Due to the lack of consensus on both definition and outcomes, our ability to perform meta-analyses and draw firm conclusions regarding evidence based treatments remains limited. Furthermore, patient involvement in determining relevant outcomes has been limited to date. This study aims to develop a consensus definition of HG and core outcome set for use in future trials, systematic reviews and guidelines on the management of HG.

Contact email address:

T.J. Roseboom, PhD
R.C. Painter, MD, PhD
I.J. Grooten, MD
J. van ’t Hooft, MD

Further Study Information

Current Stage:
December 2015 - 2016
Funding source(s):

Health Area

Disease Category
Pregnancy & childbirth

Disease Name
Hyperemesis gravidarum

Target Population

Age Range


Nature / type of Intervention


Consensus meeting
Delphi process
Systematic review

First, we will perform a systematic review of randomized controlled trials on the treatment of HG to identify previously reported characteristics to define HG and outcomes. Trial registers (including CENTRAL,, WHO ICTRP) will be searched for additional items used in the definition of HG and outcomes described in ongoing trials. Second, we will systematically identify and approach an international panel of representatives of HG stakeholders (including patients, general practitioners, midwives, dieticians, obstetricians, researchers) . Using the input from the systematic review, the international panel will complete two separate online Delphi surveys aimed at reaching consensus on both HG definition and a core outcome set. If no consensus has been reached even after additional Delphi rounds, a final consensus meeting will be organized.

Stakeholders Involved

Clinical experts
Consumers (caregivers)
Consumers (patients)
Journal editors
Patient/ support group representatives

Study Type

COS for clinical trials or clinical research

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