Developing a core outcome set for studies on Placenta Accreta Spectrum (PAS) disorder

The incidence of Placenta Accreta Spectrum (PAS) disorder 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 PAS disorder 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 PAS disorder.


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

Janet Parsons
Staff Research Scientist
Applied Health Research Centre
Li Ka Shing Knowledge Institute
St. Michael's Hospital, Unity Health Toronto
Associate Professor, Dept. of Physical Therapy, the Rehabilitation Sciences Institute,
Institute of Medical Science and Institute of Health Policy Management and Evaluation,
University of Toronto

Further Study Information

Current Stage: Ongoing
Date: January 2018 - December 2021
Funding source(s): Pending

Health Area

Disease Category: Pregnancy & childbirth

Disease Name: Pregnancy complications, Placenta Accreta Spectrum (PAS) disorder

Target Population

Age Range: 18 - 55

Sex: Female

Nature of Intervention: Any

Stakeholders Involved

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

Study Type

- COS for clinical trials or clinical research


- Consensus meeting
- Delphi process
- Systematic review
- Interview

(1) Systematic literature review to identify a list of outcomes previously reported in studies on PAS disorder;
(2) One-on-one interviews 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 set; and
(4) Consensus meeting to finalize the outcomes for inclusion in the core outcomes set.