Quantitative Tests

Quantitative Tests

Quantitative Tests

A Quantitative Test provide numerical results that are critical for precise diagnosis and treatment decisions in medical laboratories. They are essential for determining the exact concentration or amount of a substance in a sample.

Overview

This section will cover:

  • Quantitative tests and information on their details.
  • How to manage your quantitative tests.

Lab Juice

Quantitative tests measure the specific concentration of analytes in a given sample, offering precise numerical data. These tests are crucial for monitoring patient conditions, determining treatment efficacy, and ensuring accurate laboratory results.

Definitions

🗣️
**Cualia Support Docs Definitions (Public)**

Name
Definition
Actual

Actual represents the real-world value measured by the instrument being evaluated.

Agreement

Whether two values, usually the actual and reference values acceptably agreeable, based on testing requirements and/or Error Allowance.

Agreements

The total number of measurements between actual and reference value in agreement.

Analyte

Substance or chemical constituent being measured or analyzed.

Disagreement

When two values, based testing requirements and Error Allowance are outside of acceptable agreement.

Interfering Substance (IF)

An Interfering Substance (IF) is an external or endogenous compounds that can alter the outcome of a laboratory test by affecting the test's reagents, analytes, or measurement process.

Manufacturer Claim

A performance metric for a test determined by the Manufacturer through Validation

Manufacturer Insert

A document from the Manufacturer of a Test providing details on Manufacturer Claims, Procedures, warnings and any other considerations for 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.

Minimum Detectable Concentration (LoD)

The lowest concentration of an analyte that can be reliably detected by a test, distinguishing it from zero or background noise.

Quantitative

A Test Result Type that produces Results as a numerical value within a Range.

Quantitative Agreement

Quantitative Agreement uses Error Allowance as TEa or its counterparts REa, SEa, or a Custom Error rate. Actual and Expected are in Agreement when the Bias between the Results is less than the Error Allowance and the Error Index is less than 1.0

Random Allowable Error (REa)

The maximum amount of Random Error allowed for two results to be in agreement

Random Error

An error in measurement caused by factors which vary from one measurement to another.

Range

The Range between the lowest and highest value

Reference Interval Groups

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

Reference Value

The value/result that represents the true value from a trusted reference source such as a verified instrument, EQA, or a commercial product.

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.

Systematic Error

A consistent, predictable error that skews results in a specific direction. Systematic errors affect the accuracy of the test results, leading to a consistent deviation from the true value.

Systematic Error Allowance (SEa)

Acceptable shift across the detectable range of a test in a single direction.

Test

A Test is a process used to determine the presence or concentration of a substrate.

Test Abbreviation

A concise, 12-character maximum shorthand for a test, such as ALT for Alanine Aminotransferase.

Test Details

Information about a test relevant to the description, background and performance metrics.

Test Systems

A Testing System is a product, model, system or a developed process/method used in the medical laboratory setting for performing analysis of clinical samples. This can represent a system offered a Manufacturer or an LDT

Test/Analytical Measurement Range (AMR)

Range between the lowest and highest concentrations of an analyte that a test can accurately measure without dilution or concentration.

Total Allowable Error (TEa)

The set limit of combined REa and SEa tolerable for a single result. It represents the error range around an Expected result that can be considered in Agreement to an Actual result. TEa = REa + SEa

Units

The standardized measurements used to express the quantity of a substance or the outcome of a test.

Analyte

An Analyte is the substance or chemical constituent being measured or analyzed. This can include molecules like glucose, cholesterol, or more complex entities such as viral RNA or specific antigens, like those for COVID-19.

The term "analyte" is used broadly and does not differentiate based on the testing methodology, encompassing any target substance regardless of the specific analytical technique employed. There is subjectivity involved as the targets can be specific but refer to a larger group. For example, COVID as a test analyte may actually measure specific antigens or sequences.

Range (AMR)

Range represents the Analytical Measurement Range (AMR) which is the range between the lowest and highest concentrations of an analyte that a test can accurately measure without dilution or concentration.

Range MV Requirements

Validated Tests - The AMR is typically established by the manufacturer and included in the Manufacturer Insert. It is the laboratory’s responsibility to verify that the test performs accurately within this range under their specific testing conditions.

LDT Tests - For Laboratory-Developed Tests (LDTs), it is the laboratory’s responsibility to establish the AMR. This involves conducting method validation studies to determine the range over which the test can reliably measure the analyte. The laboratory must ensure that the test remains accurate, precise, and linear across this range.

Total Allowable Error (TEa)

Total Allowable Error (TEa) is the maximum permissible error/difference between Actual (sample result) and Expected (true value). Actual and Expected results within TEa are said to be in Agreement.

TEas are established through a combination of clinical requirements, regulatory standards, biological variation and performance data from validation studies. The process involves several steps to ensure that the TEa is appropriate for the intended use of the test and meets necessary quality standards.

Generally, it is best to use TEas from authoritative bodies such as CLIA, RCPA and ISO who provide acceptable error rates for many analytes.

💡
If TEas are not set, only an exact match between actual and expected values will be in agreement!

Bias Calculations

Bias=Actual−Reference\text{Bias} = {\text{Actual} - \text{Reference}}%Bias=Actual−ReferenceReference×100\text{\%Bias} = \frac{\text{Actual} - \text{Reference}}{\text{Reference}} \times 100

Total Allowable Error Units and %

TEas are presented as either a Percent (%) or Units.

Units

Units TEas allow for calculations at low concentrations to represent allowable errors more appropriately. For example, a result of 2.5 vs 2.8 ng/dL represents a 12% difference which may be beyond allowable error in % but be insignificant at only 0.3 ng/dL difference.

Percent (%)

Percent TEas allow for better representation for calculations at high concentrations. For example, a result of 500 vs 520 ng/dL would net a bias of 20 but a percent bias of 4% which could be within allowable error ranges.

Systematic and Random Allowable Error (SEa and REa)

Total Allowable Error (TEa) is the sum of Systematic Allowable Error (SEa) and Random Allowable Error (REa).

TEa=REa+SEaTEa = REa + SEa

Systematic Error is a consistent predictable deviation from the true value. This can often can be seen as a shift. For example, a test consistently returning an actual value 5 units lower than expected would be said to have systematic error.

Random error: Unpredicable variations in test results that occur due to various factors such as environmental conditions or slight differences in sample handling. Random errors affect the precision of the test results, causing variability around the true value.

Reference Interval (RI)

https://images.spr.so/cdn-cgi/imagedelivery/j42No7y-dcokJuNgXeA0ig/2c6545bd-199a-4faf-ba91-596db13a9822/2024-11-05_143647_Microsoft_Edge/w=828,quality=90,fit=scale-down

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 Intervals have a low and a high value. When a result is between this range, the results are considered to be within the RI.

Many tests have multiple Reference Interval Groups (RI Groups) to segment populations where their RI’s may be different. For example, many CBCs include different RI’s for the Male and Female groups.

Reference Interval MV Requirements

Validated Tests: Reference Intervals will be found in the Manufacturer Insert. It is the laboratory’s responsibility to verify the interval.

LDT Tests: It is the laboratory’s responsibility to determine the appropriate Reference Interval for their population.

Interfering Substances

Interfering Substances: compounds or factors that can affect the accuracy and reliability of laboratory test results. These substances can cause analytical interference, leading to false positives, false negatives, or skewed results, which can impact clinical decision-making and patient care. For example, lipemia can affect turbidimetric and colorimetric assays.

Interfering Substances MV Requirements

Validated Tests - For tests that have been validated, information about potential interfering substances is typically included in the Manufacturer Insert with concentrations of the substance and amount of effect on results. It is the laboratory’s responsibility to verify their test performance is within Manufacturer Claims.

LDT Tests - It is the laboratory’s responsibility to identify to evaluate potential interfering substances. This involves conducting thorough testing to determine if any endogenous or exogenous substances could affect the accuracy and reliability of the test results.

Subscription Plans

Free Plan Limited to 1 location, department and analyzer
Core Lab Plan Can have 1 lab, unlimited departments and analyzers
Organization Plan -Coming Soon- Unlimited labs, departments, and analyzers

Add a Quantitative Test to an Analyzer

  1. Navigate to the Analyzer
  2. Select the Quantitative Tests Tab
  3. Select “Add a Test” which will direct your browser to the test adding form
  4. Fill out the required fields submit the form

Edit Test Information

To edit Test Information, navigate to the analyzer’s test list and select the test. An edit button will appear on the test information sidebar which will direct to the test editing form.

https://images.spr.so/cdn-cgi/imagedelivery/j42No7y-dcokJuNgXeA0ig/9a45ef7d-e03a-49fb-854a-d99b5d5ac36b/20240715-175621_-_Microsoft_Edge_-_BX-3010_324232_Quantitative_Tests__Cualia_Labs_-_Cualia.io/w=1920,quality=90,fit=scale-down

Test Information

To view Test Information, navigate to the analyzer’s test list and select it. A sidebar with the test information will appear with the details and performance characteristics.

The fields for test represent various details, performance characteristics and general information about the test needed for MV experiments and quality control.

https://images.spr.so/cdn-cgi/imagedelivery/j42No7y-dcokJuNgXeA0ig/6e3a7f2a-7f53-4e49-8e26-bf81452a922c/20240715-175621_-_Microsoft_Edge_-_BX-3010_324232_Quantitative_Tests__Cualia_Labs_-_Cualia.io/w=750,quality=90,fit=scale-down

Analyte

The Analyte field allows your test to be linked to an analyte. This means that you can search your tests for what analyte they measure even if they may have different test names or specific antigens. Typing in the Analyte field will search through the analyte libraries to select the correct match or add a new analyte.

💡
As you type in the analyte search field, the suggestions will look for match base on alternative names as well. For example, “SGOT” will also produce Aspartate Aminotransferase as a result.

Test Abbreviation

The Test Abbreviation is a required field and often used throughout Cualia as a shorthand for the test.

Units

The test’s Units field shows what standardized measurement system the test uses. While it won’t affect the outcomes of MVs, it’s important to keep these set properly for clinical management of your lab.

In Quantitative Tests the field is required. In Qualitative tests the units field is optional, and part of Limit based MV experiments.

Externally Validated

The Externally Validated checkmark allows for entry about the validation that the test has already gone through. It is common for medical labs to acquire instrumentation that have already been validated by authoritative bodies such as the FDA or CE. Information on validation status will usually be offered by the manufacturer.

Range

The Range section allows for entry of a Range Low and Range High value. In many cases the best value to include is the Clinical Measurement Range or the Analytical Measurement Range. This range will usually be found in the manufacturer insert.

In an MV this range will be evaluated in the Linearity experiment.

Limit of Blank

Limit of Blank (LoB) is the highest concentration of analyte detected for a blank sample. It represents the threshold below which any measurement can be considered as noise or background signal, rather than a true indication of the analyte's presence. This value can usually be found in the manufacturer insert.

TEas

TEa % and Units

In the Cualia app, you have the ability to set TEa values, one in raw units and one in a percent. Additionally, you can specify the source of the TEa values, choosing from a list of common reputable sources such as RCPA and CLIA, or entering from your own sources.

To remove a TEa value from a test, select the X next to it.

When setting the value, you may check “Add TEa to Library” in order to make this TEa available in your standard library for all tests with the same analyte.

https://assets.super.so/870ae751-e8f4-442f-9a6a-8bdbaca88e9b/images/8d1984c0-adcd-4f9d-8ac0-c321107cb403/20240715-171400_-_Microsoft_Edge_-_Edit_Lactate_Dehydrogenase__Cualia_Labs_-_Cualia.io.gif?w=676.4931030273438

Test Systematic (SEa) and Random Error (REa) allowance %

The test’s SEa and REa percentages can be set from the slider. The two values will always add to 100%.

https://images.spr.so/cdn-cgi/imagedelivery/j42No7y-dcokJuNgXeA0ig/cb3c40a9-7d2d-4a7c-87d9-dde8cd75d186/20240715-172040_-_Microsoft_Edge_-_Edit_Lactate_Dehydrogenase__Cualia_Labs_-_Cualia.io/w=640,quality=90,fit=scale-down

Reference Intervals

Up to 5 Reference Intervals (RIs) may be added to your test. Each RI includes a group name to specify the specific population, the Lower Range and the Higher Range. For each RI, each of its fields must be filled. The order of the RIs can be re-sorted with the drag bar on the left side.

It is important for Medical Labs to verify reference intervals amongst their population. These values will be used for the MV Reference Interval experiment evaluations of the test.

Commercially available analyzers will have validated Reference Intervals available in their manufacturer inserts.

Interfering Substances

An Interfering Substance (IF) is an external or endogenous compounds that can alter the outcome of a laboratory test by affecting the test's reagents, analytes, or measurement process.

Up to 5 Interfering Substances may be added to a test. Each IF involved a substance name (eg hemolysis) and an allowable error. The allowable error is the maximum % change in reported concentration from a sample without the IF in the sample substrate.

It is important to for medical labs to verify manufacturer claims of maximum error from interfering substances in the MV process. These values will be used in Cualia’s MV tooling for evaluation.

Test Description

The test Description is an optional field to enter any general information about the test.

Delete a Test

To delete a test, enter the edit form for the test and select Delete Test. A confirmation modal will appear. After confirmation the test will be deleted and will redirect back to the analyzer.

FAQs

How many tests can my analyzer have?

An analyzer can have unlimited tests.

How will editing test fields affect MVs?

Cualia is designed to be robust and fulfill the requirements of a high throughput laboratory. Any changes made to a test will not affect any MVs regardless of approval status.

MV’s in progress will be able to import changes made to the analyzer’s test. Any test fields that do not match the state of the analyzer will show a purple border that allows you to sync the changes automatically.