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The headline number for your trial
Try it freeClinical trial feasibility
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Check your eligibility rules against real US health data. In minutes.
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Meet your US Population Twin
Move the sliders. See how many people share your profile.
…US adults match this profile
Counted from sex, age, BMI and smoking. Blood pressure only changes the risks.
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Educational simulation based on CDC NHANES 2015–2018. Not medical advice.
Top health risks
Validated on published research
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Pick a trial and watch its rules apply.
Each square is 1% of the starting group. Squares fade as each eligibility rule removes people.
1 square = 1% of 243.8 million US adults
On all five trials the published number falls inside our range, within about 1 percentage point.
37.4%91.2 million US adults qualify
- Trial Fit
- 91.2 million
- Published
- 93.0 million
Published number is inside our range −0.7 pts
See the full report
Our range
83.2 million – 99.2 million
Published source
Wong et al., Cardiovasc Drugs Ther 2023
Rule by rule
Of 243.8 million US adults, about 91.2 million (37.4%) meet every rule we can check. Biggest cut: Obesity (BMI 30+), or overweight (BMI 27+) with a weight-related health problem (removes 47% of the group).
Same rules, using the standard medical cut-offs (for example blood pressure 140/90). This reproduces the numbers in the researchers' own flowchart.
Same 243.8 million starting population. Paper rules as written give 42.2%; classic thresholds reproduce the paper's flowchart.
- No diabetes85.0%
- Obesity (BMI 30+), or overweight (BMI 27+) with a weight-related health problem38.4%
- No previous weight-loss surgery37.5%
- No kidney failure37.4%
Source: Wong et al., Cardiovasc Drugs Ther 2023. Data: CDC NHANES 2015–2018. Shares are of US adults.
- Trial Fit
- 91.3 million
- Published
- 93.4 million
Published number is inside our range −0.9 pts
See the full report
Our range
83.3 million – 99.3 million
Published source
Wong et al., Cardiovasc Drugs Ther 2024
Rule by rule
Of 243.8 million US adults, about 91.3 million (37.5%) meet every rule we can check. Biggest cut: Obesity (BMI 30+), or overweight (BMI 27+) with a weight-related health problem (removes 47% of the group).
Same rules, using the standard medical cut-offs. This reproduces the numbers in the researchers' own flowchart.
Same group and definitions as STEP 1. Only diabetes and prior obesity surgery are excluded.
- No diabetes85.0%
- Obesity (BMI 30+), or overweight (BMI 27+) with a weight-related health problem38.4%
- No previous weight-loss surgery37.5%
Source: Wong et al., Cardiovasc Drugs Ther 2024. Data: CDC NHANES 2015–2018. Shares are of US adults.
- Trial Fit
- 16.4 million
- Published
- 16.8 million
Published number is inside our range −0.2 pts
See the full report
Our range
14.4 million – 18.3 million
Published source
Bress et al., JACC 2016
Rule by rule
Of 219.4 million US adults, about 16.4 million (7.5%) meet every rule we can check. Biggest cut: Age 50 or older (removes 57% of the group).
We followed the rules exactly as the published paper describes them, including its heart-risk score. This already matches the researchers' number, so no adjustment was needed.
Matches step by step: 43.3 → 17.1 → 12.1 → 7.5% of adults vs 43.3 → 17.0 → 12.0 → 7.6% published.
- Age 50 or older43.3%
- Blood pressure in the trial's range (top number about 130–180)17.1%
- High risk of heart attack or stroke (heart or kidney disease, age 75+, or high risk score)12.1%
- No diabetes8.5%
- No previous stroke7.9%
- No large amounts of protein in the urine7.8%
- No heart failure7.5%
- No kidney failure or dialysis7.5%
Source: Bress et al., JACC 2016. Data: CDC NHANES 2007–2012. Shares are of US adults.
- Trial Fit
- 1.8 million
- Published
- 1.86 million (1.59–2.12)
Published number is inside our range −0.4 pts
See the full report
Our range
1.5 million – 2.0 million
Published source
Wong, Fan, Pak, Diab Vasc Dis Res 2020
Rule by rule
Of 27.5 million US adults with type 2 diabetes, about 1.8 million (6.4%) meet every rule we can check. Biggest cut: Has heart disease or had a stroke (removes 78% of the group).
We followed the rules exactly as the published paper describes them. This already matches the researchers' number, so no adjustment was needed.
Same 27 million adults with type 2 diabetes. Small difference at the HbA1c step (‘on treatment’ is not defined in the paper).
- Has heart disease or had a stroke21.9%
- Blood sugar (HbA1c) in the trial's range: 7–9%, or 7–10% if on treatment7.3%
- BMI 45 or below6.8%
- Kidneys working well enough (eGFR 30 or more)6.4%
- No signs of serious liver damage6.4%
Source: Wong, Fan, Pak, Diab Vasc Dis Res 2020. Data: CDC NHANES 2007–2016. Shares are of US adults with type 2 diabetes.
- Trial Fit
- 6.3 million
- Published
- 6.2 million
Published number is inside our range +0.0 pts
See the full report
Our range
4.5 million – 8.1 million
Published source
Lu et al., Circ CQO 2024 (2017–2020)
Rule by rule
Of 134.5 million US adults aged 45+, about 6.3 million (4.7%) meet every rule we can check. Biggest cut: Has heart disease or had a heart attack or stroke (removes 53% of the group).
Also leaves out people a doctor ever told they have diabetes. This one change reproduces the researchers' 4.7% exactly.
Paper rules as written give 7.0 million; adding self-reported diabetes gives 6.3 million.
- Overweight or obesity (BMI 27+)62.7%
- Has heart disease or had a heart attack or stroke9.3%
- No diabetes (blood test, medicines, or ever told by a doctor)4.7%
Source: Lu et al., Circ CQO 2024 (2017–2020). Data: CDC NHANES 2017–March 2020. Shares are of US adults aged 45+.
Before you ask sites
Tune the criteria first. Ask sites once.
Manual feasibility asks specific sites how many patients they can recruit. It takes weeks and costs thousands.
Trial Fit answers a different question in minutes: what share of US adults meet your criteria, and which rule cuts the most people.
Trial Fit
- Time
- Minutes
- Cost
- Free preview, $349 report
- Based on
- Examined people, CDC NHANES
Manual feasibility
- Time
- Weeks
- Cost
- Thousands to tens of thousands
- Based on
- Estimates from sites
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Ask about itQuestions
The headline number for your trial is free. The full report — range, the rules that exclude the most people, which rule to relax, what can't be checked, assumptions and a PDF — is $349, one-time. Payments are in test mode during the preview.
Ideally the full protocol. A ClinicalTrials.gov ID works too, but it usually lists only a summary of the criteria (STEP 1 shows a few; its protocol has 35), so the number is less precise.
Files are read in your browser; only the text is sent to compute the report. We don't publish or share it.
On the five trials with published reference numbers, Trial Fit is within about 1 percentage point of published reference numbers (absolute: e.g. 37.4% vs 38% for STEP 1), and all published numbers fall inside our range. For other trials there is no reference, so the report shows every assumption and what can't be checked. Try them on the home page.
No. A feasibility study asks your sites how many patients they can recruit. Trial Fit comes before it: in minutes it shows what share of US adults meet your criteria and which criterion cuts the most people, so you can tune the protocol first and run site feasibility once, on the final version.
The United States today (CDC NHANES). The UK, EU and others are next.
No. AI only translates the wording into rules from a fixed list of survey questions; you review them, and the engine computes every number.