Core Outcome Set (COS)

Core Outcome Set (COS)

CTD & GAMT caregivers, patients, and clinicians–We want to hear from you!

Researchers across the globe are studying treatments to improve care for individuals with Creatine Transporter Deficiency (CTD) and GAMT Deficiency (GAMT). Those research projects need appropriate outcome measures to determine if they are successful.

The Delphi Survey aims to assist caregivers, patients, and clinicians in identifying a meaningful core outcome set.

Round 3 will be the final survey and will go live in August. If you participated in Round 1 and/or Round 2, you will receive a personalized survey link when it opens.

What are outcomes?

  • Outcomes are used to determine if a treatment is effective or not.
  • Outcomes may include how someone feels, what they can do, observable symptoms, or results of lab tests.

What is a Core Outcome Set (COS) and why is a COS used?

  • A ‘Core Outcome Set’ is a small set of outcomes that are established as important and should be collected in every research study of the same disease.
  • An established COS prevents studies from reporting only a selection of the outcomes that were measured. It is expected that they report on all outcomes in the COS.

Why is a COS important?

  • If researchers measure different outcomes, it is hard to compare and contrast the effectiveness of interventions or treatments.
  • A COS will help us compare CTD and GAMT deficiency studies to identify which treatments work best.

How can I contribute?

In multiple rounds of an online survey, we will show you a list of outcomes related to CTD and GAMT deficiency and ask you to rate how important each outcome is to you. The survey will be available in English, French, and Spanish. As a rare disease community, we need as many patients, caregivers, and clinicians as possible to participate!

Who is eligible?

  • Adult patients (18 years or older) diagnosed with CTD or GAMT deficiency
  • A parent or caregiver of a person diagnosed with CTD or GAMT deficiency
  • A health care professional experienced in caring for patients with CTD or GAMT deficiency (e.g., geneticist, dietician, physical therapist, speech therapist, psychologist, neurologist, etc.)

What is the time commitment?

  • You will be asked to complete 2-3 surveys within the next 3-5 months.
  • Each survey will take about 1 hour to complete.
  • After each survey you complete, you will be entered into a drawing to win:
    • One of five Amazon gift cards valued at $50 USD for the first survey round
    • One of five Amazon gift cards valued at $75 USD for the second survey round
    • If a third survey round is required, additional Amazon gift cards will be awarded

What is a Delphi Survey?

  • A survey designed to gather opinions from multiple people and eventually reach consensus
  • Delphi surveys are confidential to ensure that everyone has an equal say.
  • Delphi surveys have multiple rounds (usually between 2 and 3). This means that participants get more than one chance to give their opinion.
  • The figure below outlines the steps involved in a Delphi survey:

What happens in Round 1 of the Delphi Survey?

  • The research team has developed a list of possible outcomes that we want to ask you about. We created this list after looking at many research papers, analyzing data from our CreatineInfo Patient Registry, and conducting focus groups with parents/caregivers of CTD and GAMT deficiency patients.
  • In round 1, we will ask you to rate the importance of each outcome on a scale from 1 to 9.
  • When you complete the survey, your ratings will be sent back to the research team along with the ratings from all other participants. We will then summarize the responses for each participant group (patients, parents/caregivers, and health care professionals) in a graph. These graphs will be included in round 2 of the Delphi Survey.

What happens in round 2 (and possibly round 3) of the Delphi Survey?

  • We will ask you to complete the survey again. You will be given a reminder of how you rated each outcome last time. You will also see the summary graph showing how each group rated the outcomes. No one can see another individual participant’s ratings, you can only see the overall results for each group as a whole.
  • Looking at your previous ratings and the summary graphs, we will ask you if you would like to stick with your original rating or change it. You are not under any pressure to change your rating if you don’t want to. It is perfectly fine for you to stick to your own rating even if you rated the outcome differently than the majority of the group.
  • The research team will review the results from round 2 and decide if a 3rd round is needed. In that case, the steps above would be repeated in round 3.

What happens after the Delphi Survey?

  • After the last round, you will be invited to discuss the results in a virtual meeting. You can decide later if you would like to participate in the meeting.
  • At the end of this process, the research team will produce a report on the outcomes that patients, parents/caregivers, and health care professionals agreed were the most important outcomes. These are called the ‘core outcomes’ for CTD and GAMT Deficiency in children and youth.

This information is adapted from the Core Outcome Measures in Effectiveness Trials initiative,

Why are we doing round 2?

Round 2 is your chance to see how others rated each outcome and reconsider your rating. A Delphi survey is a consensus survey. This means the end goal is to come to a decision together.

Why am I seeing an overview of responses from other participants?

A Delphi survey is a consensus survey. This means that we work as a group to come to an agreement throughout the process.

Why are there so many outcomes?

The outcomes come from multiple sources, including scientific literature, caregiver focus groups, and ACD’s patient registry. Our team originally gathered over 1,000 outcomes and condensed those to the list of 85 you saw in round 1. Through the Delphi process, we will reduce this to the final 8-10 outcomes.

Why are some of the outcomes so similar?

The outcomes we gathered came from many sources. Sometimes different terms are used for similar outcomes. This is why we need your help to find the most accurate terms for the most important outcomes for GAMT and CTD.

All of these outcomes are important! What should I do?

  • This is the tricky part! Since our goal is to reduce this list to 8-10 outcomes for a final COS, we will need to be slightly more selective in which outcomes we rate as “most important”.  
  • Please be selective in which outcomes you rate as “most important”. Reminder, our goal is to reduce these outcomes down to 8-10.

What happens after round 2?

We will do a third and final round of the Delphi survey, approximately 1 month later. In round 3, you will be asked to rank your most important outcomes. After round 3, there will be a final consensus workshop with a small group of patients, caregivers, and CCDS experts to finalize the COS.

How do I participate?

If you completed the previous round(s), you will receive an email with a personalized email link. If you did not participate in round 1 or did not receive a personalized email link, you can participate by clicking this link.

I did not complete round 1. Can I still participate in round 2?

Yes, you can participate in round 2 even if you did not complete round 1.

Why did we remove outcomes in round 2?

Only outcomes that were rated “Important” or “Most Important” by at least 70% of participants in round 1 were included in round 2. This is intentional and part of the consensus process.

What happened to my comments from round 1?

Round 1 comments will be shared and discussed in the consensus meeting, helping us arrive at the best final Core Outcome Set.

Link to Round 2 FAQ Sheet PDF

If you have questions please contact Emily at

Establishing Core Outcome Sets (COS) for CTD and GAMT deficiency

Why are we doing this study?

Researchers across the globe are studying treatments to improve care for individuals with Creatine Transporter Deficiency (CTD) and GAMT Deficiency (GAMT). Those research projects need appropriate outcome measures to determine if they are successful.

Study Goal:

To develop Core Outcome Sets for CTD and GAMT deficiency.