Results Summary

PCORI funded the Pilot Projects to explore how to conduct and use patient-centered outcomes research in ways that can better serve patients and the healthcare community. Learn more.


Treatments for many health problems don’t work the same way in all people. A person’s age, sex, health problems, genes, and other factors can affect how well a treatment will work. For example, a treatment might work well in most people with a heart problem but not very well for people who also have diabetes. Researchers usually do not look at how well a treatment works for different groups of individuals (e.g., men and women, those with or without diabetes). This makes it harder for doctors to use research study results when treating their patients.

Project Purpose

The researchers used a statistical approach called subgroup analysis to determine whether the results of a study differ for specific groups of people. Then they developed a computer program to help determine where individual patients fit into the different groups; this program is intended to be used by doctors and patients when making treatment decisions.

The researchers asked whether this approach would be useful for helping clinicians and patients take study results into account when making treatment decisions. They tested this approach with data from a wide variety of medical research studies.


The researchers looked at results from 32 studies involving treatments for different medical conditions.

Each study

  • Had 1,000 or more participants
  • Split participants by chance into two or more groups to compare treatments
  • Had a specific goal for treatment

The researchers compared the following information in each study:

  • Patient details, such as age, gender, and other health conditions
  • How well the treatment worked

The researchers made sure the patient information was complete for each study they examined. If some information was missing, then they checked to make sure that the missing information wouldn’t change the results.

The researchers used the information from these comparisons to determine how well each treatment would be expected to work, on average, for most patients. Then they compared this with what happened for different groups of patients in each study.


The researchers found that, how well treatments worked varied a lot for different groups of people. Often, results from some groups of patients made it look like the treatment was effective for everyone in the study. But many other patients in the study didn’t get much benefit from the treatment. For example, in one diabetes study, most of the benefit was limited to the quarter of participants at highest risk from the disease.

In a few cases, only a small group of patients in the study actually benefited from the treatment at all, but because the benefit for these small groups was so large, it appeared that the treatment worked well for everyone.


The researchers only had information about the treatment and the patients that was provided in the publication describing each study. Some studies provided more information than others. If researchers had more information across all studies, they might have had different results. Also, the researchers could have used other proven statistical techniques for studying differences between groups. These techniques might have produced different results.

Importance of Findings

In studies of medical treatments, it is common for treatments to work better for some people than others. If researchers only look at how well a treatment works overall, they might miss important information about who is more likely to benefit from the treatment and who is likely to receive unnecessary treatment.

If researchers used information about patients (such as age, gender, and other health conditions) when looking at the results of studies, which the researchers in this study found is possible to do, they could tell doctors which groups of people are most likely to benefit from a treatment. This information could help doctors and patients make better decisions about whether a treatment is right for an individual patient.

Sharing the Results

The researchers has published journal articles about their research and held a meeting to present the findings of this study to doctors and researchers. The presentation was recorded and is available at

PCORI has funded the research team to undertake a project to advance the use of these research results to improve health care in real-world settings.

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Project Information

David M. Kent, MD, MS
Tufts Medical Center Inc.
Assessing and Reporting Heterogeneity of Treatment Effect in Clinical Trials

Key Dates

June 2012
May 2015

Study Registration Information


Has Results
Award Type
Funding Type
State State The state where the project originates, or where the primary institution or organization is located. View Glossary
Last updated: April 29, 2022