Methods
Protocol registration
The detailed protocol was prospectively registered with COMET
(Registration Id: 1489)
(http://www.comet-initiative.org/) and submitted to
a peer reviewed journal. The study is reported according to the PRISMA
statement (Figure S1).10
Study selection
Studies describing completed core outcome sets specific to maternal or
neonatal health were included if they developed or applied methodology
for determining which outcomes should be measured, or are important to
measure in clinical trials, research or clinical practice. Studies were
eligible if they related to pregnant or postpartum participants (up to
12 months postpartum), or neonates/infants (where the first outcome
measurement is recommended within the first 28 days of birth), with any
health condition and in any setting. Published conference papers were
included if they provided adequate information about the completed COS
or where a primary paper provided further information.
Excluded studies
Consistent with Gargon et al. papers were excluded if the design or
rationale reported (i) a single study; (ii) related to pre-clinical or
early phase trials only; (iii) reported the use of a COS; (iv) a
systematic review of clinical trials; (v) studies of prognosis; (vi)
studies of outcomes measured in clinical trials or quantitative
descriptions of outcomes; (vii) based on the opinion of a single author;
(viii) or focused on one domain/outcome only.5 We
excluded papers relating to early pregnancy loss (prior to 20 weeks
gestation) as these were considered gynaecological rather than
maternity.
Information sources
We searched the COMET11 and CROWN4registers and ICHOM (International Consortium for Health Outcomes
Measurement) list of standard sets.12 We conducted an
electronic database search of MEDLINE (via Ovid), EMBASE and CINAHL
Complete (via EBSCOhost) in January 2020. Studies reported in English
language were included from inception to January 2020. All ongoing COS
identified in the COMET register and in previous
reviews2,5,6,13-17 were searched for updates of
progress. Hand-searching reference lists complimented the search.
Search
A university health librarian helped to develop and pilot the search
strategy. Our search terms combined three concepts (‘core outcome set’,
‘methodology’ and ‘population’). All terms within each concept were
combined with the Boolean operator OR and then the three concepts with
AND. Search terms are outlined in Appendix S1.
Study selection and data
management
Endnote software X8 was used to screen all citations. Duplicates were
identified and removed. Titles and abstracts were screened by one author
(VS). Full text papers were reviewed for all studies meeting the
inclusion criteria. Papers not meeting the eligibility criteria were
excluded and reason recorded. Full paper screening was conducted
independently by one researcher (VS). Ten percent of included and
excluded papers were assessed by a second reviewer (DC). Any
disagreement between reviewers or uncertainty were resolved by consensus
or by arbitration using a third reviewer (JG).
Data extraction
Data were extracted by one author (VS) using extraction forms guided by
criteria outlined in previous reviews:2,6 author(s),
year of publication, COMET registration number, disease category,
disease name, related papers, funder, CROWN registration, publication
type, each item as defined on the COS-STAR
statement18, scope, stakeholder involvement,
geographical location of stakeholders, patient participation, consensus
process, final list of outcomes/domains, and measurement
recommendations.
Sources of information
Supporting data was collected from primary COS papers, relevant project
papers (systematic reviews and protocols) and from the COMET and CROWN
registers.
Assessment of study against minimum
standards
Included studies were assessed against COS-STAD minimum
standards.8 COS-STAD contains 11 standards covering
three key domains (scope, stakeholders, and consensus process).
Consistent with others,9 item 9 (‘A scoring
process and consensus definition is described a priori ’) was modified
to include two assessment items for scoring process (termed 9a) and
consensus definition (termed 9b). Each item was assessed as standard
met, unclear, or not met using the assessment criteria outlined by
Gargon and colleagues.9
Synthesis of results
Findings were described descriptively using text and tables and
summarised as frequencies and percentages.