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=3. Additional resources for selecting and implementing informatics solutions - Part 2: Other vendors and service providers=
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==3.2 Medical diagnostics instrumentation and equipment vendors==
==Sandbox begins below==
===3.2.1 CLIA-certified vendors===
{{raw:wikipedia::Detection limit}}
Medical diagnostics laboratories perform various types of testing, including point-of-care testing. At least in the United States, the [[Clinical Laboratory Improvement Amendments]] (CLIA) test complexities, as determined by the U.S. Food & Drug Administration (FDA)<ref name="FDA_CLIA18">{{cite web |url=https://www.fda.gov/medical-devices/ivd-regulatory-assistance/clia-categorizations  |title=CLIA Categorizations |author=U.S. Food & Drug Administration |date=22 March 2018 |accessdate=20 January 2020}}</ref>, and resulting public CLIA Database provide insight into the instrumentation and equipment vendors marketing equipment for diagnostic and research laboratories. While not a complete list of instrument and equipment vendors, the CLIA-approved vendor lists below make an excellent starting point for laboratories seeking to add to its testing inventory.
 
 
The following two tables list vendors verified to sell CLIA-waived instruments and/or test kits. CLIA-waived instruments and test kits are deemed as being simple to use and as having little chance in providing wrong information or harming someone. The vendors were pulled from the FDA's [http://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/Databases/ucm142437.htm downloadable CLIA file] from January 2020. The file was sorted to pull out the CLIA-waived devices, and then the vendors were researched to see if they still actively marketed the listed product(s). In some cases, the vendor listed on the FDA file was acquired by another company. If the associated products were still found to be marketed by the acquiring company, that company name was used. CLIA-waived device and test kit types are given as a general guide to what CLIA-waived items the vendor offers.
 
'''Note''': Do not assume that just because a vendor is listed here all of its offerings are CLIA-waived. Some of these vendors may also sell analyzers and tests that are CLIA-certified as moderate or complex, as well as a variety of other non-CLIA-certified solutions. Additionally, this listing does not name the specific CLIA-waived item(s). It is ultimately up to the potential buyer to verify with the vendor that a specific item is CLIA-waived before purchase.
{{Vendors of CLIA-waived items}}
 
The following is a list of additional vendors verified to offer CLIA-certified moderate or complex diagnostic instruments and/or test kits. The same methodology was used as above for CLIA-waived, with the exception of opting to not provide specifics about instrument and test types.
 
'''Note''': Most of these vendors sell analyzers and tests that are CLIA-certified moderate or complex. However, is ultimately up to the potential buyer to verify with the vendor an item's CLIA certification status before purchase.
{{Vendors of CLIA-certified moderate or complex items}}
 
===3.2.2 Other vendors===
As previously mentioned, some vendors manufacturing and distributing medical diagnostic and research solutions don't get their instruments and tests CLIA certified in the U.S. It's beyond the scope of this guide to attempt to list them all, but a few representative examples include:
 
* [https://www.abacusdiagnostica.com/ Abacus Diagnostica Oy]
* [https://www.zeiss.com/meditec/int/home.html Carl Zeiss Meditec AG]
* [http://devyser.com/ Devyser AB]
* [https://www.diapro.it/ Dia.Pro Diagnostic Bioprobes Srl]
* [http://en.dynamiker.com/ Dynamiker Biotechnology (Tianjin) Co., Ltd.]
* [http://www.dynextechnologies.com/ Dynex Technologies, Inc.]
* [http://entrogen.com/ EntroGen, Inc.]
* [https://www.eppendorf.com/US-en/ Eppendorf AG]
* [https://www.euroclonediagnostica.it/ Euroclone Diagnostica Srl]
* [http://www.fast-trackdiagnostics.com/ Fast Track Diagnostics Luxembourg Sàrl]
* [https://www.hitachi-hightech.com/global/ Hitachi High-Technologies Corporation]
* [http://www.htz.biz/index.htm HTZ Ltd.]
* [http://www.htz.biz/index.htm Humasis Co., Ltd.]
* [https://www.virion-serion.de/en/ Institut Virion\Serion GmbH]
* [https://www.jeolusa.com/ JEOL USA, Inc.]
* [https://www.launchdiagnostics.com/ Launch Diagnostics Ltd.]
* [https://www.mt.com/us/en/home.html Mettler-Toledo International, Inc.]
* [http://www.mkldiagnostics.com/ MKL Diagnostics AB]
* [https://www.healthcare.nikon.com/en/ Nikon Corporation]
* [https://www.novatec-id.com/ NovaTec Immundiagnostica GmbH]
* [https://medical.olympusamerica.com/ Olympus Corporation of the Americas]
* [https://www.orgentec.com/en/ ORGENTEC Diagnostika GmbH]
* [https://www.sartorius.com/ Sartorius AG]
* [https://www.shimadzu.com/ Shimadzu Corporation]
* [https://en.vircell.com/ Vircell SL]
* [https://www.waters.com/ Waters Corporation]
 
Also, see BioPharmGuy's [https://biopharmguy.com/links/company-by-location-diagnostics.php worldwide diagnostics companies, by location].
 
==3.3 EHR vendors==
An electronic health record (EHR) is "defined as a longitudinal collection of electronic health information about individual patients and populations."<ref name="GunterTerryEHR">{{cite journal |title=The Emergence of National Electronic Health Record Architectures in the United States and Australia: Models, Costs, and Questions |author=Gunter, T.D.; Terry, N.P. |journal=Journal of Medical Internet Research |volume=7 |issue=1 |page=e3 |year=2005 |doi=10.2196/jmir.7.1.e3 |pmid=15829475 |pmc=PMC1550638}}</ref> It is a record in digital format that is theoretically capable of being shared across different health care settings. In some cases, this sharing can occur by way of network-connected enterprise-wide information systems and other information networks or exchanges.
 
In the United States, many EHRs have been certified by the Office of the National Coordinator's (ONC) Health IT Certification Program. Those certifications are based on "standards, implementation specifications and certification criteria adopted by the Secretary."<ref name="HITAbout19">{{cite web |url=https://www.healthit.gov/topic/certification-ehrs/about-onc-health-it-certification-program |title=About The ONC Health IT Certification Program |work=HealthIT.gov |author=Office of the National Coordinator for Health Information Technology |date=27 March 2019 |accessdate=20 January 2020}}</ref> The ONC's ''Certified Health IT Product List'' is an excellent resource for browsing EHR and [[electronic medical record]] (EMR) vendors. It can be found at [https://chpl.healthit.gov/ https://chpl.healthit.gov/]. One approach is to click the "Browse All' button, then on the new screen select "Certification Status" and uncheck "Suspended by ONC" and "Suspended by ONC-ACB." That will give you a list of active results. Of course, you can apply additional filters, compare products (including certification criteria and clinical quality measures), and download results.
 
==3.4 Patient outreach and engagement solution vendors==
 
 
==3.5 Laboratory billing service providers==
 
 
==References==
{{Reflist|colwidth=30em}}

Latest revision as of 18:25, 10 January 2024

Sandbox begins below

Template:Short description

The limit of detection (LOD or LoD) is the lowest signal, or the lowest corresponding quantity to be determined (or extracted) from the signal, that can be observed with a sufficient degree of confidence or statistical significance. However, the exact threshold (level of decision) used to decide when a signal significantly emerges above the continuously fluctuating background noise remains arbitrary and is a matter of policy and often of debate among scientists, statisticians and regulators depending on the stakes in different fields.

Significance in analytical chemistry

In analytical chemistry, the detection limit, lower limit of detection, also termed LOD for limit of detection or analytical sensitivity (not to be confused with statistical sensitivity), is the lowest quantity of a substance that can be distinguished from the absence of that substance (a blank value) with a stated confidence level (generally 99%).[1][2][3] The detection limit is estimated from the mean of the blank, the standard deviation of the blank, the slope (analytical sensitivity) of the calibration plot and a defined confidence factor (e.g. 3.2 being the most accepted value for this arbitrary value).[4] Another consideration that affects the detection limit is the adequacy and the accuracy of the model used to predict concentration from the raw analytical signal.[5]

As a typical example, from a calibration plot following a linear equation taken here as the simplest possible model:

where, corresponds to the signal measured (e.g. voltage, luminescence, energy, etc.), "Template:Mvar" the value in which the straight line cuts the ordinates axis, "Template:Mvar" the sensitivity of the system (i.e., the slope of the line, or the function relating the measured signal to the quantity to be determined) and "Template:Mvar" the value of the quantity (e.g. temperature, concentration, pH, etc.) to be determined from the signal ,[6] the LOD for "Template:Mvar" is calculated as the "Template:Mvar" value in which equals to the average value of blanks "Template:Mvar" plus "Template:Mvar" times its standard deviation "Template:Mvar" (or, if zero, the standard deviation corresponding to the lowest value measured) where "Template:Mvar" is the chosen confidence value (e.g. for a confidence of 95% it can be considered Template:Mvar = 3.2, determined from the limit of blank).[4]

Thus, in this didactic example:

There are a number of concepts derived from the detection limit that are commonly used. These include the instrument detection limit (IDL), the method detection limit (MDL), the practical quantitation limit (PQL), and the limit of quantitation (LOQ). Even when the same terminology is used, there can be differences in the LOD according to nuances of what definition is used and what type of noise contributes to the measurement and calibration.[7]

The figure below illustrates the relationship between the blank, the limit of detection (LOD), and the limit of quantitation (LOQ) by showing the probability density function for normally distributed measurements at the blank, at the LOD defined as 3 × standard deviation of the blank, and at the LOQ defined as 10 × standard deviation of the blank. (The identical spread along Abscissa of these two functions is problematic.) For a signal at the LOD, the alpha error (probability of false positive) is small (1%). However, the beta error (probability of a false negative) is 50% for a sample that has a concentration at the LOD (red line). This means a sample could contain an impurity at the LOD, but there is a 50% chance that a measurement would give a result less than the LOD. At the LOQ (blue line), there is minimal chance of a false negative.

Template:Wide image

Instrument detection limit

Most analytical instruments produce a signal even when a blank (matrix without analyte) is analyzed. This signal is referred to as the noise level. The instrument detection limit (IDL) is the analyte concentration that is required to produce a signal greater than three times the standard deviation of the noise level. This may be practically measured by analyzing 8 or more standards at the estimated IDL then calculating the standard deviation from the measured concentrations of those standards.

The detection limit (according to IUPAC) is the smallest concentration, or the smallest absolute amount, of analyte that has a signal statistically significantly larger than the signal arising from the repeated measurements of a reagent blank.

Mathematically, the analyte's signal at the detection limit () is given by:

where, is the mean value of the signal for a reagent blank measured multiple times, and is the known standard deviation for the reagent blank's signal.

Other approaches for defining the detection limit have also been developed. In atomic absorption spectrometry usually the detection limit is determined for a certain element by analyzing a diluted solution of this element and recording the corresponding absorbance at a given wavelength. The measurement is repeated 10 times. The 3σ of the recorded absorbance signal can be considered as the detection limit for the specific element under the experimental conditions: selected wavelength, type of flame or graphite oven, chemical matrix, presence of interfering substances, instrument... .

Method detection limit

Often there is more to the analytical method than just performing a reaction or submitting the analyte to direct analysis. Many analytical methods developed in the laboratory, especially these involving the use of a delicate scientific instrument, require a sample preparation, or a pretreatment of the samples prior to being analysed. For example, it might be necessary to heat a sample that is to be analyzed for a particular metal with the addition of acid first (digestion process). The sample may also be diluted or concentrated prior to analysis by means of a given instrument. Additional steps in an analysis method add additional opportunities for errors. Since detection limits are defined in terms of errors, this will naturally increase the measured detection limit. This "global" detection limit (including all the steps of the analysis method) is called the method detection limit (MDL). The practical way for determining the MDL is to analyze seven samples of concentration near the expected limit of detection. The standard deviation is then determined. The one-sided Student's t-distribution is determined and multiplied versus the determined standard deviation. For seven samples (with six degrees of freedom) the t value for a 99% confidence level is 3.14. Rather than performing the complete analysis of seven identical samples, if the Instrument Detection Limit is known, the MDL may be estimated by multiplying the Instrument Detection Limit, or Lower Level of Detection, by the dilution prior to analyzing the sample solution with the instrument. This estimation, however, ignores any uncertainty that arises from performing the sample preparation and will therefore probably underestimate the true MDL.

Limit of each model

The issue of limit of detection, or limit of quantification, is encountered in all scientific disciplines. This explains the variety of definitions and the diversity of juridiction specific solutions developed to address preferences. In the simplest cases as in nuclear and chemical measurements, definitions and approaches have probably received the clearer and the simplest solutions. In biochemical tests and in biological experiments depending on many more intricate factors, the situation involving false positive and false negative responses is more delicate to handle. In many other disciplines such as geochemistry, seismology, astronomy, dendrochronology, climatology, life sciences in general, and in many other fields impossible to enumerate extensively, the problem is wider and deals with signal extraction out of a background of noise. It involves complex statistical analysis procedures and therefore it also depends on the models used,[5] the hypotheses and the simplifications or approximations to be made to handle and manage uncertainties. When the data resolution is poor and different signals overlap, different deconvolution procedures are applied to extract parameters. The use of different phenomenological, mathematical and statistical models may also complicate the exact mathematical definition of limit of detection and how it is calculated. This explains why it is not easy to come to a general consensus, if any, about the precise mathematical definition of the expression of limit of detection. However, one thing is clear: it always requires a sufficient number of data (or accumulated data) and a rigorous statistical analysis to render better signification statistically.

Limit of quantification

The limit of quantification (LoQ, or LOQ) is the lowest value of a signal (or concentration, activity, response...) that can be quantified with acceptable precision and accuracy.

The LoQ is the limit at which the difference between two distinct signals / values can be discerned with a reasonable certainty, i.e., when the signal is statistically different from the background. The LoQ may be drastically different between laboratories, so another detection limit is commonly used that is referred to as the Practical Quantification Limit (PQL).

See also

References

  1. IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version:  (2006–) "detection limit".
  2. "Guidelines for Data Acquisition and Data Quality Evaluation in Environmental Chemistry". Analytical Chemistry 52 (14): 2242–49. 1980. doi:10.1021/ac50064a004. 
  3. Saah AJ, Hoover DR (1998). "[Sensitivity and specificity revisited: significance of the terms in analytic and diagnostic language."]. Ann Dermatol Venereol 125 (4): 291–4. PMID 9747274. https://pubmed.ncbi.nlm.nih.gov/9747274. 
  4. 4.0 4.1 "Limit of blank, limit of detection and limit of quantitation". The Clinical Biochemist. Reviews 29 Suppl 1 (1): S49–S52. August 2008. PMC 2556583. PMID 18852857. https://www.ncbi.nlm.nih.gov/pmc/articles/2556583. 
  5. 5.0 5.1 "R: "Detection" limit for each model" (in English). search.r-project.org. https://search.r-project.org/CRAN/refmans/bioOED/html/calculate_limit.html. 
  6. "Signal enhancement on gold nanoparticle-based lateral flow tests using cellulose nanofibers". Biosensors & Bioelectronics 141: 111407. September 2019. doi:10.1016/j.bios.2019.111407. PMID 31207571. http://ddd.uab.cat/record/218082. 
  7. Long, Gary L.; Winefordner, J. D., "Limit of detection: a closer look at the IUPAC definition", Anal. Chem. 55 (7): 712A–724A, doi:10.1021/ac00258a724 

Further reading

  • "Limits for qualitative detection and quantitative determination. Application to radiochemistry". Analytical Chemistry 40 (3): 586–593. 1968. doi:10.1021/ac60259a007. ISSN 0003-2700. 

External links

Template:BranchesofChemistry Template:Authority control