QNT Reference Interval

QNT Reference Interval

Quantitative Reference Interval (RI)

Overview

Other Names - Normal Range, Reference Range, Expected Values, Biological Reference Interval, Normal Limits

A Reference Interval MV experiment determines the range of values expected for a healthy population, verifying the test's clinical applicability.

Definitions

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**Cualia Support Docs Definitions (Public)**

Name
Definition
Experiment

A sampling of results that are statistically analyzed and interpreted in the evaluation of testing performance.

Label

The general identification used to identify a specific Sample.

Method Validation

A systematic process to evaluate whether the performance of a medical Test meets quality goals to be used for medical testing.

Method Verification

A systematic process to evaluate whether the performance of a medical Test meets quality goals set by a validation. Performance evaluations may usually be found in a manufacturer insert.

Min. Samples Per Range

The minimum number of eligible samples required in order for the Reference Interval to be set. For a verification we recommend minimum 20 samples.

Reference Interval (RI)

The range of values that includes the central 95% of a healthy population's test results. It is derived from a large sample of healthy individuals to ensure accuracy and reliability. It is often considered the normal range of results for a healthy person.

Reference Interval (RI) Experiment

An experiment used to determine the normal ranges for a test within populations measured by the laboratory

Reference Interval Groups

Classifications used to segment reference intervals based on specific characteristics of the population such as age or gender.

Result(s)

A value or determination collected by measurement or calculation.

Results Within Range (%)

The percent of the population results that must be within the Reference Interval for it to be confirmed. We recommend a 95% to match with statistical confidence intervals for populations.

Sample(s)

Individual specimens collected for testing representing the source. In MV experiments with Runs, this can refer to to the number of concentration levels used.

What is the Reference Interval Experiment?

The Reference Interval Experiment is an MV Experiment used to establish the range of values within which a healthy population's test results are expected to fall. This experiment ensures that a laboratory method produces results consistent with clinical expectations and helps differentiate between normal and abnormal values. The reference interval is typically determined by measuring a representative sample from a healthy population and analyzing the distribution of results to define the upper and lower limits, often encompassing the central 95% of the data.

The experiment involves rigorous data collection and statistical analysis to confirm that the method performs accurately and consistently within the defined interval. It considers variables such as age, sex, ethnicity, and other relevant factors that may influence the distribution of results. By validating these intervals, the experiment verifies that the method can be used to reliably interpret clinical outcomes, providing critical support for diagnosis, monitoring, and treatment decisions in healthcare settings.

In an MV it is the laboratory’s responsibility to confirm a population reference interval.

Experiment Settings and Acceptance Criterias

Set up the Test’s Reference Intervals

It is recommended to set up the Reference Intervals in the Test Settings for the Organization’s Analyzer, however this can be done in the MV’s Test Settings as well. In Cualia, up to 5 Reference Interval Groups may be set and evaluated.

For information on how to set them please see the section on Quantitative Tests: Reference Intervals.

Define Acceptance Criterias

In Cualia’s Reference Interval Experiment there are 2 Acceptance Criterias:

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Min. Samples Per Range: The minimum number of eligible samples required in order for the Reference Interval to be set. For a verification we recommend minimum 20 samples.

Results Within Range (%): The percent of the population results that must be within the Reference Interval for it to be confirmed. We recommend a 95% to match with statistical confidence intervals for populations.

Sample Selection

For each Reference Interval Group, select samples that represent the a normal member of the general population.

Testing Samples

Measure each sample and enter in the data within its Reference Interval Group.

Preparation Checklist

Analyzer is set up in Cualia → AnalyzersAnalyzers
Tests are set up in the analyzer → Quantitative TestsQuantitative Tests and Qualitative TestsQualitative Tests
The initial MV details are prepared → MV Overview and DetailsMV Overview and Details

General Experiment Recommendations: Dos and Don’ts

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Don’t: Enter private patient information, identifiers or data into Cualia.
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Don’t: Rush Through an MV: Sometimes an MV can take months waiting for the right samples to come through. Based on our experience, the most time consuming part of an MV is finding out after days after measurements and painstakingly entering in the data to find that something was done incorrectly and the cycle must be repeated.
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Don’t: Rely too much on controls, calibrators and spiked samples: The goal of an MV is not to pass inspection but to truly evaluate that your instrumentation’s performance is up to clinical standards. Using samples that reflect the lab’s testing population will offer the best insights into the evaluation
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Do: Prepare your Cualia MV before taking measurements: Having a blueprint of work provides a smooth experience.
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Do: Enter Results Directly into Cualia: Taking down results to enter them into a spreadsheet just to copy them into Cualia will increase sources of error. When a result is returned, enter it directly into Cualia. You will be able to immediately have feedback into the success state of the experiment, identifying any missing variables that will hinder your MV.
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Do: Ask for clarification. Talk to regulators, auditor, consultants and don’t hesitate to reach out to support@cualia.io with questions.

Data Table

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  1. Tabs to select the Reference Interval group to enter data.
  2. Click to open up the options for Reference Interval Groups to Add/Remove them from the experiment.
  3. Select the toggles to set whether to include the Reference Interval Group in the experiment.
  4. Click and drag the handlers to reorder the Reference Interval Groups.
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Data Table Columns

Label | Free text - The general identification used to identify a specific Sample.

Source | Free text - The original source of the Sample such as Patient, EQA, or the name of the Manufacturer

Actual | Pos or Neg Label only - Represents the real-world value measured by the instrument being evaluated.

Result | Read Only - Indicates whether the measurements are within agreeable range.

(blank) - No result. The sample is likely to be ineligible for calculation because it is missing an actual and/or reference value.

(✓) → The individual result is out of agreement range and/or unacceptable Error Index

(✓) → The individual result within agreement range and/or acceptable Error Index

Experiment Pass / Fail

Each Reference Interval Group Acceptance

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Results: The number of eligible samples much exceed the Min. Samples Per Range requirement set in the Acceptance Criterias.

In Range: The percent of the samples measured that are within the Reference Interval.

When both Results and In Range are satisfied, the Reference Interval is verified and considered Passed.

Reference Interval Experiment Acceptance

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When all Reference Interval Groups have passed, the experiment will be verified and pass.