Final Research Report

View this project's final research report.

Peer-Review Summary

Peer review of PCORI-funded research helps make sure the report presents complete, balanced, and useful information about the research. It also confirms that the research has followed PCORI’s Methodology Standards. During peer review, experts who were not members of the research team read a draft report of the research. These experts may include a scientist focused on the research topic, a specialist in research methods, a patient or caregiver, and a healthcare professional. Reviewers do not have conflicts of interest with the study.

The peer reviewers point out where the draft report may need revision. For example, they may suggest ways to improve how the research team analyzed its results or reported its conclusions. Learn more about PCORI’s peer-review process here.

In response to peer review, the PI made changes, including

  • Providing more detail about the analyses, particularly about how missing data were handled. Data were missing mostly because participants did not complete the follow-up assessment. The researchers did not believe it was appropriate to impute data for entire questionnaires so they did not account for missing data in their analyses of the primary outcomes. These analyses were conducted only for the 76 percent of randomized participants who provided follow-up, which raised concerns about how well the results reflect the study population as a whole.
  • Describing sensitivity analyses where the researchers reanalyzed outcomes for only those participants who completed treatment, in response to reviewers’ concerns about the effect of the high dropout rate from the intervention program.
  • Laying out the differences in the number and format of group sessions between the compared interventions. The researchers indicated in their response to reviewers that they did not believe there were material effects of these differences on the outcomes given their experience with these interventions in past studies.
  • Explaining why longitudinal follow-up assessments were added late in the study rather than being part of the original study protocol. The researchers added information to the report indicating that they obtained additional funding late in the study to complete the longitudinal analyses.

Conflict of Interest Disclosures

Project Information

Carol A. Mathews, MD*
Kevin Delucchi, PhD
The Regents of the University of California, San Francisco
Comparison of Peer-Facilitated Support Group and Cognitive Behavioral Therapy for Hoarding Disorder

Key Dates

September 2013
April 2018

Study Registration Information

*Carol A. Mathews, MD, who was at University of California, San Francisco when this project was awarded, is now at University of Florida.


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Health Conditions Health Conditions These are the broad terms we use to categorize our funded research studies; specific diseases or conditions are included within the appropriate larger category. Note: not all of our funded projects focus on a single disease or condition; some touch on multiple diseases or conditions, research methods, or broader health system interventions. Such projects won’t be listed by a primary disease/condition and so won’t appear if you use this filter tool to find them. View Glossary
Populations Populations PCORI is interested in research that seeks to better understand how different clinical and health system options work for different people. These populations are frequently studied in our portfolio or identified as being of interest by our stakeholders. View Glossary
Intervention Strategy Intervention Strategies PCORI funds comparative clinical effectiveness research (CER) studies that compare two or more options or approaches to health care, or that compare different ways of delivering or receiving care. View Glossary
State State The state where the project originates, or where the primary institution or organization is located. View Glossary
Last updated: March 4, 2022