A core outcome measurement set for hyperemesis gravidarum research: a consensus study

Background
Outcome reporting in hyperemesis gravidarum (HG) research lacks standardization, which hampers the aggregation of data. A core outcome set (COS) for HG research has been developed to increase standardization. While a COS represents which key outcomes should be measured, it does not describe how and when they should be measured. Our aim was to develop a consensus-based core outcome measurement set for HG complementing the existing COS for HG.

Method
This study included multiple phases: (1) systematic review to identify all existing outcome measurement instrument (OMI)s in HG research; (2) a consensus meeting with the steering committee of this study to vote for one best OMI per outcome; (3) a modified Delphi consultation survey of at least 100 stakeholders including patients, obstetric healthcare professionals, other healthcare professionals and researchers to achieve consensus on one OMI per outcome.

Results
The literature review identified 362 unique OMIs in 461 studies. The modified Delphi consultation round included 155 stakeholders including researchers (12.3%), women or families with lived experiences (51%), obstetric healthcare professionals (20%), and other healthcare professionals (12.9%) representing 10 countries. We achieved consensus (> 70% agreement) on all 24 OMIs presented during the Delphi survey including validated questionnaires such as the Pregnancy Unique Quantification of Emesis 24 h (PUQE-24) score and the EQ-5D-5 L as well as standardized definitions for outcomes such as preterm birth and babies small-for-gestational-age. Consensus was achieved on an OMI for each outcome included in the COS.

Conclusions
We developed a consensus-based set of core outcome measurements to record the previously established COS for studies in HG. This core outcome measurement set describes how outcomes included in the COS should be measured and reported. The COS and core outcome measurement set should be used in all future HG trials. This will help further standardize outcome selection, collection, and reporting in HG trials.