Core Outcome Measures in Effectiveness Trials

Developing a core outcome set for studies on women with invasive placentation

General Information

The incidence of invasive placentation worldwide varies from 1.7 (95% CI 1.4-2.0) in the U.K. to 14.4 (95% CI 13.4-15.4) in Canada per 10,000 deliveries. Despite its rarity, it is significant as the incidence has risen dramatically in recent decades , from 1 in 4,027 pregnancies in the 1970s to 1 in 533 pregnancies in the 2000s, and will continue to rise, paralleling the increasing Caesarean delivery rates worldwide. Screening, diagnosing, and managing invasive placentation remains challenging, partially due to the many, often conflicting, outcomes reported in the literature. Prospective studies are necessary to address these knowledge gaps. In order for these studies to translate into improved patient care, and to meaningfully compare outcomes between studies, it is important to have a core set of outcomes considered important by patients and all other stakeholders involved in the care of these patients. The goal of this project is to develop a core outcome set for invasive placentation.

Principal Investigator:
Susan O’Rinn
Senior Project Manager – Research, Women and Babies Program, Department of Evaluative Clinical Sciences, Sunnybrook Research Institute, Toronto, Canada
Institute of Health Policy, Management, and Evaluation, University of Toronto, Toronto, Canada

Rohan D’Souza
Assistant Professor, Division of Maternal and Fetal Medicine, Department of Obstetrics & Gynaecology, Mount Sinai Hospital, University of Toronto, Toronto, Canada

Jon Barrett
Waks Family Chair in Maternal Fetal Medicine Research
Professor University of Toronto
Program Research Director Women and Babies Program
Division Chief of MFM Sunnybrook Health Science Centre
Co-Director, Clinical Trials Services (CTS)/The Centre for Mother, Infant and Child Research (CMICR)

John Kingdom
Professor, Division of Maternal and Fetal Medicine, Department of Obstetrics & Gynaecology, Mount Sinai Hospital, University of Toronto, Toronto, Canada

Further Study Information

Current Stage:
January 2018 - 2020
Funding source(s):

Health Area

Disease Category
Pregnancy & childbirth

Disease Name
Pregnancy complications

Target Population

Age Range
18 - 55


Nature / type of Intervention


Consensus meeting
Delphi process
Focus group(s)
Literature review
Systematic review

(1) Systematic Literature review to identify a list of outcomes previously reported in studies of the treatment of invasive placentation;
(2) Focus Groups to identify important outcomes from the perspectives of patients, healthcare providers, and other stakeholders;
(3) Delphi Survey to arrive at a consensus on the outcomes that should comprise the core outcome; and
(4) Consensus Meeting to finalize the outcomes for inclusion in the core outcomes set.

Stakeholders Involved

Clinical experts
Consumers (caregivers)
Consumers (patients)
Journal editors
Policy makers
Service providers
Service users

Study Type

COS for clinical trials or clinical research

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