A REVIEW ARTICLE ON AT HOME DIAGNOSTIC KITS

Table of Contents

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A REVIEW ARTICLE ON AT HOME DIAGNOSTIC KITS

1 ABSTRACT

2  INTRODUCTION

• Definition: A diagnostic test is any approach used to gather clinical information for the purpose of making a clinical decision (i.e., diagnosis)[1]. Diagnostic kits are developed to simplify these diagnostic tests.
• Diagnostic kits are of great importance in clinical practice since they assist clinicians for establishing positive or negative disease condition of patients. In the early 1990s, the first point-of-care tests for use in resource-constrained settings became commercially available: lateral flow immunoassays (often called rapid diagnostic tests) for the diagnosis of malaria.Today, more than 40,000 products are available worldwide for the in vitro diagnostic testing of different class of diseases or conditions. These include traditional laboratory-based tests, with samples being sent to a central laboratory for analysis, and point-of-care tests, which can be performed at the point of patient care or at certain specified area.Well defined following, six steps must be addressed when selecting an in vitro diagnostic test: (i) defining test’s purpose; (ii) reviewing market and checking each product’s specification; (iii) reviewing the test’s regulatory approval; (iv) obtaining data on the diagnostic accuracy of the test under ideal conditions (i.e. in laboratory-based evaluations); (v) obtaining data on the diagnostic accuracy of the test in clinical practice; and (vi) monitoring the test’s performance in routine use[2].

In order to use any clinical test appropriately, it is essential that several parameters must be established regarding the test and that these are taken into consideration to make firm decision.A diagnostic test is any approach used to gather clinical information for the purpose of making a clinical decision (i.e., diagnosis).  Diagnostic kits are used to simplify these diagnostic tests that are easy to interpret compared to traditional diagnostic tests. These kits work on the principle of identification of predetermined parameters. These diagnostic kits has been developed over decades to increase compliance for user. Diagnostic kits has been developed from simple paper based detection to microchips along with digital readout meter. In this review article information about what is diagnostic kits, consideration of parameters for correct selection of diagnostic kits, development of diagnostic kits over the years, types of diagnostic kits as per their mechanism of action, future aspects to develop diagnostic kits.

Conclusion: Significant progress has been made during past years; however, the research on POCT based analytical devices is still in its early stage. Greater & more precise efforts will be needed in this field to develop into widely and precisely used kits to become a more matured platform technology in diagnostic, point-of-care and environmental monitoring applications. Despite many potential future directions in this research, here, we hope to convey to the reader just a few of the perspective directions that we think are relevant and attractive in this field.

• Reliability refers to the consistency and repeatability of outcomes as measured by the clinical test. It refers to the inter examiner agreement.
• Validity refers to whether the clinical test is accurate in measuring for what it is meant to be measured.
• Therefore, most clinical tests are used to classify patients as “positive” or “negative” depending on the presence or absence (respectively) of a particular sign or symptom, which is then presumed to be indicative of the presence or absence of the condition (i.e. a “positive” test result indicates that the patient’s condition).These parameters include the test’s sensitivity, specificity, predictive values, and likelihood ratios.Specificity is determined as specific results under predetermined conditions, sensitivity refers to how test results under different conditions,predictive values depends on results obtained as per predetermined conditions whether the result is positive or negative.The sensitivity of a clinical test is the proportion of subjects with the condition who are correctly identified by the test and provide a “positive” result. Thus, if the sensitivity is high, a “negative” test result will effectively rule out the condition.The specificity is the proportion of subjects without the condition who are correctly identified by the test and provide a “negative” result. Thus, if the specificity is high, a “positive” test result will effectively rule in the condition.Predictive values are considered as usefulness of tests, they are also both influenced by the prevalence of the condition in the population to whom the test is applied.

Condition Present Absent Test Result Positive a b Negative c d a = “True Positives”  Sensitivity = a/(a + c)b = “False Positives” Specificity = d/(b +d)c = “False Negatives” Positive predictive value = a/(a + b)d = “True Negatives” Negative predictive value = d/(c + d)

Figure A: An illustration of how to calculate the sensitivity, specificity, positive predictive value, and negative predictive value for a clinical test from a 2 ´2 contingencytable.

Likelihood ratio of a positive test = (sensitivity)/ (1 – specificity)Likelihood ratio of a negative test = (1 – sensitivity)/ (specificity)The higher the likelihood ratio of a positive test, the more certain one can be that a positive test result indicates the subject has the condition. A value of 10 or more is considered an indicator that a positive test result is very good at ruling in the condition.The lower the likelihood ratio of a negative test, the more certain one can be that a negative test result indicates the subject does not have the disorder. A value of 0.1 or less is considered an indicator that a negative test result is very good at ruling out the condition.If a likelihood ratio is close to 1.0, then the test result is not a good indicator whether the subject has (for a positive test result) or does not have (for a negative test result) the condition.

Two other parameters, namely the likelihood ratios of a positive and negative test, have been suggested to be better indicators of the usefulness of a clinical test, these parameters are used  to overcome some of the misleading results if present any.These above parameters are added to validate other parameters if any area is not covered because different conditions require different views to handle[3].

FDA gave general guidelines that how should Home Use Tests should work which are as follows:

• Accuracy:  A measure of agreement between a test result and an accepted reference value. Example: If you have a standardized reference material at a known value (such as 180 mg/dl of cholesterol), accuracy measures how close the result of the test you are using will get to the known value. You may have a test that is very precise yet very inaccurate, which would be the case if your device measures 180 mg/dl of cholesterol reproducibly as 240 mg/dl.
• Analyte:The part of the sample that the test is designed to find or measure.  Example: A home pregnancy test measures human chorionic gonadotropin (hCG) in urine. The analyte is hCG.
• Approved Test: A test that has been approved by FDA, based on the manufacturer’s data showing that it is safe and effective for its intended use.
• For a new type of test, or for a test that presents higher risk to the patient, the manufacturer performs studies to show that the test does what it claims to do and does not present any unreasonable risk. The manufacturer submits the results in a “premarket approval application” that FDA reviews. If FDA approves the application, the manufacturer can begin selling the test.
• Cleared Test: A test that has been cleared by FDA, based on the manufacturer’s data showing that it is similar to other tests that are already being sold. For a test that is similar to others already on the market and that is considered to have low risk to the user, manufacturers submit information to show that the test performs similarly to the other tests. The manufacturer submits the results in a “premarket notification” that FDA reviews. If FDA determines that the test is substantially equivalent to another test, the manufacturer can begin selling the test.
• Exempt Test: A test that is considered to have such low risk to the patient that FDA does not require manufacturers to submit any premarket approval application or notification.
• False Negative: A test result that incorrectly says the analyte, disease, or condition is not present when it actually is present. False negatives can be due to human error, test error, or substances in the sample that interfere with the test. Example: A woman who is pregnant receives a test result saying that she is not pregnant.
• False Positive: A test result that incorrectly says the analyte, disease, or condition is present when it is actually not present. False positives can be due to human error, test error, or substances in the sample that interfere with the test. Example: A woman who is not pregnant woman receives a test result saying she is pregnant.
• Indications For Use: A description of why a patient would use a certain test.
• Intended Use: A description of what the manufacturer intended to measure with a certain test.
• In Vitro Diagnostic Test: A medical test that analyzes body samples, such as blood, urine, stool, or saliva, for specific components or analytes.
• Label: Written material and instructions that accompany the medical test. Labeling includes the writing on the outside of the box as well as instructions packaged with the test.
• Over-The-Counter(OTC) Tests: Tests that can be purchased and used by anyone at home. These do not require a doctor’s prescription.  If manufacturers intend to sell their test kits over the counter, they must demonstrate that untrained lay persons can perform the tests and get good results.
• Package Insert: Information about the test and/or instructions that come inside the box or package.
• Qualitative Test: A test that gives results in terms of negative or positive. Example: Pregnancy tests, ovulation tests, and drugs of abuse detection tests indicate whether or not the person has the condition.
• Quantitative Test: A tests that gives results in terms of numbers. Example: Glucose meters indicate how much glucose is present in the sample.
• Screening Test: An initial or preliminary test. Screening tests do not tell you if you definitely have a disease or condition. Rather, positive results indicate that you may need additional tests or a doctor’s evaluation to see if you have a particular disease or condition[4].

Some of the critical components used to build diagnostic kits are solid phase components (plates, membranes), antibodies or antigens, conjugates and PCR master mixes. Wash buffers and diluents are also used to build diagnostic kits but are not a critical components[5].

Table 1Gold Standard Assays to determine the Diagnostic Sensitivity & Specificity of Antigen test kits[5]

Agent	Gold Standard
Avian Influenza Virus	Virus Isolation
Avian Leukosis Virus	COFAL
Bovine Virus Diarrhea	Virus isolation/ rtPCR
Canine Parvovirus	HA/HI
Classical Swine Fever	Virus Isolation
Feline Immunodeficiency Virus	Virus Isolation
Foot & mouth Disease Virus	Virus Isolation
Giardia lambia	Fecal wet mount
Infectious Bovine Rhinotracheitis Virus	Virus Isolation
Parvovirus (canine)	Virus Isolation/fecal hemagglutination
Heartworm (canine or feline)	Necropsy worm count, with breakdown into the number of male & female worms (acceptable to compare to a licensed kit for negative samples, to avoid sacrificing healthy animals)
Mycobacterium avium spp. paratuberculosis	Fecal culture
Transmissible Spongiform Encephalopathies	Immunohistochemistry on obex

Table 2Gold Standard Assays to determine the Diagnostic Sensitivity & Specificity of Antibody test kits[5]

Sr. No.	Antibody specific for	Gold Standard	Sr. No.	Antibody specific for	Gold Standard
	Anaplasma phagocytophilum	IFA, samples from Northeast & upper Mid-west		Feline Immunodeficiency	SN
	Anaplasma platys	IFA, samples from Southwest & Mid-south		Foot & Mouth Disease	SN
	Avian Encephalomyelitis	SN		Infectious Bovine Rhinotracheitis	SN
	Avian Influenza	SN/HI		Infectious Bursal Disease	SN
	Avian Reovirus	AGID		Infectious Laryngotracheitis	SN
	Avian Rhinotracheitis	SN		Leptospira canicola, L. grippotyphosa, L. icterohaemorrhagiae, L. Pomona (combined)	MAT
	Babesiosis	CF		Tuberculosis (Mycobacterium Bovis)	caudal fold test/ agent isolation
	Blue tongue	CF		Johnes’ Disease	Fecal culture
	Bovine leukemia	SN		Mycoplasma gallisepticum	Agglutination
	Borrelia burgdorferi	IFA		Mycoplasma meleagridis	Agglutination
	Caprine Arthritis-Encephalitis	AGID		Mycoplasma synoviae	Agglutination
	Canine Leptospira	micro-agglutination		Neospora canimum	SN
	Chicken Anemia Virus	SN/IFA		Newcastle Disease Virus	HI
	Egg Drop Syndrome	HI		Ornithobacterium rhinotracheale	ELISA
	Erlichia Canis	IFA		Porcine Reproductive & Respiratory Syndrome	SN/ immunoperoxdase monolayer assay
	Erlichia ewingii	Species-specific ELISA assay		Pseudorabies	SN
	Epizootic Hemorrhagic Disease	SN		Swine influenza	SN
	Equine Infectious Anemia	AGID	Where, SN= serum neutralization HI=hemagglutination inhibition IFA= indirect fluorescent antibody AGID= agar gel immunodiffusion MAT= microscopic agglutination test ELISA= enzyme-linked immunosorbent assay
	Feline Infectious Peritonitis	SN

 

3 HISTORY OF DIAGNOSTIC KITS AND IT’S EVOLVEMENT

Table 3Origin and development of diagnostic kits over time[6-42]

Scientific Advancements	Policy Milestones
1953: DNA structure defined by Watson & Crick.	1964: Cancer marker a-1 fetoprotein (AFP) was described as tumor-associated marker.
1965: Social security amendments authorizing Medicare & Medicaid.	1966: AMA establishes & publishes first CPT coding system.
1967: Clinical Laboratory Improvement Act (CLIA)-Federal government enacts licensing, regulatory authority over clinical laboratories.	1968: First fully automated discrete chemistry analyzer for whole blood or serum.
1973: First system to measure blood gas, metabolites, electrolytes & CO-oximetry from a single sample.	1973: Federal Register published new FDA regulations on labeling requirements & procedures for standards for diagnosis.
1976: Discovery of hemoglobin glycosylation.	1976: Medical devices amendments to Food, Drug & Cosmetic Act.
1977: Sanger develops method of DNA sequencing.	1979: First Point-of-Care device developed.
1983: Social Security Amendments enacted, including Medicare prospective payment system based on DRGs	1984: Deficit Reduction Act requires labs to bill Medicare directly; creates Clinical Laboratory Fee Schedule to cap payments for lab services.
1985: HER-2/ neu gene is closed.	1985: Mullis develops Polymerase Chain reaction (PCR) for copying DNA.
1985: First diagnostic test to screen blood & blood products for HIV.	1986: First automated DNA sequencer is produced.
1988: First-generation test kits for Chlamydia trahamatis & Neisseria gonorrhea infectious.	1988: Clinical Laboratory Amendments consolidate regulation of all clinical laboratories under one statue.
1990: Human Genome Project launches.	1990: Safe Medical Devices Act.
1990: Negotiated Rule making Act enacted.	1992: Safe Medical Device Amendments establish single reporting standard for user facilities, manufacturers, & distributers.
1993: Relationship of Type-1 diabetes & degree of glycemic control demonstrated.	1993: ICD-10 codes first released by WHO as an option to replace ICD-9 codes.
1994: BRCA-1, the first breast cancer susceptibility gene, is discovered.	1995: First fully automated for high-volume blood screening laboratories.
1996: Heath Insurance Portability & Accountability Act (HIPAA) enacted.	1997: FDA Modernization Act.
1998: First targeted treatment (Herceptin) for HER-2/ neu positive metastatic breast cancer patients.	1998: EU in In vitro Diagnostics Directive.
1999: FDA Draft Guidance on Labeling for Laboratory Tests.	1999: Balanced Budget Refinement Act of 1999 pays outpatient clinical laboratory tests at Critical Access Hospitals (CAHs) on a reasonable cost basis versus a fee schedule.
2000: Medicare, Medicaid, & SCHIP Benefits Improvement & Protection Act of 2000 (BIPA).	2001: Final rule in Federal register establishes NCDs for 23 diagnostic tests as a result of negotiated rulemaking with industry stakeholders.
2001: Launch of a rapid anthrax test.	2001: First non-invasive glucose monitor using a low electric current to take glucose readings without puncturing the skin.
2001: Publication of initial Human Genome Program working draft sequence- Collins & Venter.	2002: Medical Device User Fee & Modernization Act.
2002: First fully-automated congestive heart failure test for diagnosis & monitoring treatment response.	2002: FDA Office of IVD Device Evaluation & Safety (OVID) formed to consolidate regulatory oversight of diagnostics.
2002: CMS publishes interim final rule regarding inherent reasonableness (IR) authority.	2003: West Nile virus blood screening assay available for use by U.S. manufacturers.
2003: Compliance required for IVDD: all IVD products must be “CE marked” or be prohibited from sale in EU.	2003: First fully automated, high-throughput diagnostic instrument for detecting Chlamydia trachamatis Neisseria gonorrhea.
2003: FDA draft guidance for pharmacogenomics data submissions released.	2003: Medicare Prescription Drug, Improvement & Modernization Act (MMA) enacted.
2004: First pharmacogenomic array to identify variations in drug metabolism.	2004: Freeze on clinical laboratory fee schedule becomes effective through 2008.
2004: First oral specimen rapid HIV test.	2005: Genetic Information Nondiscrimination Act of 2005.
2006: Vaginal discharge self-test to facilitate management of vaginal symptoms.	2006: Improve self-monitoring of blood glucose in type 2 diabetic patient.
2007: Home-based self-sampling and self-testing for sexually transmitted infections.	2007: User acceptability and feasibility of self-testing with HIV rapid tests.
2007: Home-based versus clinic-based self-sampling and testing for sexually transmitted infections.	2008: The reliability of point‐of‐care prothrombin time testing.
2009: Free self-test for screening albuminuria.	2009: HIV rapid tests.
2011: Own rapid HIV test in the emergency department.	2011: The uptake and accuracy of oral kits for HIV self-testing..
2011: Microfluidics-based diagnostics of infectious diseases.	2012: Rapid HIV tests to screen sexual partners
2014: A paper-based microfluidic electrochemical immunodevice for the detection of cancer bio-markers.	2014: A digital microfluidic electrochemical immunoassay.
2014: Non-invasive mouth guard biosensor for continuous salivary monitoring of metabolites	2015: “Paper machine” for molecular diagnostics.
2015: Label‐free blood analysis at the point‐of‐living.	2015:Smartphone dongle for simultaneous measurement of hemoglobin concentration and detection of HIV antibodies.
2015:Point-of-care anemia detection device.	2015:Color‐based assay for detecting severe anemia.
2015: Rapid quantification of cell-free DNA in patients with severe sepsis.	2015: A microfluidic platform with digital readout.
2015:Direct detection and drug-resistance profiling of bacteremias using inertial microfluidics.	2015:A point of care test for the determination of amniotic fluid.
2015: Wearable temporary tattoo sensor for real-time trace metal monitoring in human sweat.	2015: Wearable salivary uric acid mouthguard biosensor with integrated wireless electronics.
2015: Smart bandage with wireless connectivity for uric acid biosensing as an indicator of wound status.	2015: Epidermal devices for noninvasive, precise, and continuous mapping of macro vascular and micro vascular blood flow.
2016: Fully wearable sensor arrays for multiplexed in situ perspiration analysis.	2016: Rapid, low-cost detection of Zika virus using programmable bio molecular components.
2016: Point-of-care molecular detection of Zika virus.	2016: Vertical-flow paper SERS system for therapeutic drug monitoring of flucytosine in serum.
2016: Monitoring sepsis using electrical cell profiling.	2016: Real-time microfluidic blood-counting system.
2016: Portable cancer diagnostic tool.	2017: Diagnostics of glucose in sweat.

Twenty years ago, with the development of the Clinical Laboratory Improvement Amendments of 1988 (CLIA ’88), the clinical laboratory industry embarked on a bold new experiment in point-of-care testing (POCT)[43].

Among various kinds of POCT devices history of paper based diagnostic kits were developed by following means: Paper-based bio-analysis dates back to the early 20th century, and a big breakthrough is the invention of paper chromatography for which Martin and Synge were awarded the Nobel Prize in chemistry in 1952. Typically, these tests are based on a strip of paper (or membrane) immobilized with capture antibody specific to an antigen of interest. When the sample is applied, the antigen binds to another antibody (conjugate antibody) which is conjugated to a signal indicator (e.g., colloidal gold)[44].

The first commercial immunochromatographic lateral flow strip was used for human chorionic gonadotropin detection in the early 1980s[45].

Simple Paper based POCT evolved to Microfluidic creation on paper that, not only helps to save the amount of reagent or sample used for a test, but also provides opportunities to have multiple tests on the same platform by creating different reaction zones for different analyte detection For paper-based biosensors, mostly the following four different biological probes are used: enzymatic amino acid/protein, immunoantibody/antigen, DNA/aptamer and synthetic polymers[45].

The most common detection technique for paper-based sensors is the colorimetric assay, which works on the principle of the color change of paper as a result of chemical or biological reactions. Low-cost, easy readouts by the naked eye and simple integration with point-of-care systems have made the colorimetric assay a primary choice of readout techniques in paper-based analytical devices[46].

To overcome the limitations of colorimetric assays, an alternative, electrochemical detection method has been integrated with paper-based microfluidic devices. This technique produces electrical signals based on a chemical reaction and can be easily quantified. Electrochemical technique is an attractive detection technique for paper-based assays because of small size, portability, simplicity, low cost, high sensitivity and selectivity by proper choice of detection potential[47].

Also Paper based POCT diagnosis has evolved for detection of various Biomarkers & whole-cell analysis.Applications include tests for cancer biomarkers, proteins, pathogens, drugs, hormones and metabolites in biomedical, food and environmental settings[45].

In vitro diagnostics (IVD) refers to tests for disease or infection on samples that are removed from the body for analysis.  In clinical diagnostics, these samples are typically fluids such as blood, urine, saliva, and sometimes, cerebrospinal fluid, or secretions and cells from the nose, throat, vagina, or an open wound. Various technologies are used to test for infections and analyze the proteins, genes, enzymes, and other analytes that are indications to one degree or another of a health problem[48].

Over the years, the use of diagnostics tests has grown beyond its original role as a tool for making or confirming a diagnosis. Today, health care providers are able to catch disease early and so prevent more dire health consequences; to better manage treatment; and thanks to recent advances in molecular testing, to predict the likelihood of future health problems.

Table 4 Diagnostic kit assessment at the time of detection[48]

	WHAT THE TESTS DO	WHAT THEY MATTER
SCREENING	RISK ASSESSMENT
These tests go beyond family & medical history to evaluate the likelihood of an individual developing a particular condition.	Lifestyle changes can sometimes be made or treatment done to minimize risk or the impact of the condition should it develop.
EARLY DETECTION
Routine & at-risk screening tests that ay catch disease in its early stages.	Disease impacts can be minimized, & sometimes prevented, if caught early enough for treatment.
ASSESSMENT	DIAGNOSIS
Tests that confirm or rule out specific diagnosis.	Needed to understand next steps in care.
STAGING & PROGNOSIS
Tests used to determine how advanced or severe a condition might be or its predicted course. May also be to assess risk of recurrence & to inform adjuvant therapy decisions.	Determines whether & what kind of treatment is necessary.
MANAGEMENT	THERAPY SELECTION
Tests that predict the effectiveness & potential side effects of specific treatments.	Avoids suffering & wasted time from, & cost of, unproductive treatments.
MONITORING/TREATMENT ASSESSMENT
Tests that ensure ongoing safety & effectiveness of prescribed treatments or course of care	Enables timely intervention to adjust or change treatment as necessary.

The thousands of in vitro tests depend on telltale indicators captured in samples taken from the body to communicate to health care providers what may be amiss with the patient. These indicators and how they are detected and measured define the four disciplines into which the tests are organized[48]:

1. Chemistry: Chemistry tests measure or detect specific substances in the body to determine if they are present or present in “normal” amounts.
2. Hematology:  Hematology tests focus on blood and the components of blood.
3. Microbiology:  Microbiology tests look for agents of infectious disease, including bacteria, viruses, parasites, mycobacteria, and fungi, or the body’s immune response (typically antibodies) to these microbes.
4. Molecular:  Molecular tests analyze DNA, RNA, or the expression of proteins.

Table 5Different categories of diagnostic test kits[48]

	CHEMISTRY	HEMATOLOGY	MICROBIOLOGY	MOLECULAR
SCREENING	RISK ASSESSMENT
Cholesterol (cardiovascular disease)	Platelet count (risk of bleeding)	Rubella antibody (determines immunity in pregnant woman, risk of infection if exposed to virus)	BRCA1
BRCA2
Factor V Leiden & PT 20210 (risk of blood clots)	Cystic fibrosis (CF) Mutation panel (carrier status in prospective parents-risk of passing on the disease)
EARLY DETECTION
BUN, creatinine (kidney damage or disease)	Hemoglobin (anemia)	Hepatitis C antibody test (hep C infection) PCR or culture screening (determine bacterial presence in pregnant woman that may be harmful to newborn if passed during birth)	CIDNA (screen for DS in pregnant woman at risk of having baby with DS)
PCR screening (determine bacterial presence in pregnant woman that may be harmful to newborn if passed during birth)
ASSESSMENT	DIAGNOSIS
Hemoglobin A1c (diabetes)	CBC (anemia)	Hepatitis C RNA test (distinguish between current & past Hep C infection)	Hepatitis C RNA test (distinguish between current & past Hep C infection)
CF Mutation Panel (cystic fibrosis)
Immunophenotyping (leukemia)	Blood culture (septicemia)	PML-RARA (leukemia)
Mycobacterial culture (Tuberculosis)	BCR-ABL (leukemia)
STAGING & PROGNOSIS
CEA (cancer)	Bone marrow aspiration, biopsy (leukemia)	HIV viral load (HIV infection)	KRAS mutation (lung, colon cancer)
eGFR (kidney disease)
CCP antibody (RA)
MANAGEMENT	THERAPY SELECTION
TPMT (who can safely receive thiopurines )	PML-RARA (likely benefit from treatment with all-trans retinoic acid)	Antimicrobial susceptibility testing (many infections)	HER2/neu (breast cancer)
MONITORING/TREATMENT ASSESSMENT
CEA (cancer) Hemoglobin A1c (diabetes)	PT/INR (Warfarin therapy)	Hepatitis C viral load (hep C infection)	Hepatitis C viral load (hep C infection)
HIV viral load (HIV infection)	HIV viral load (HIV infection)
Repeat mycobacterial cultures (assess drug response & clearance of tuberculosis)	PML-RARA (quantitative)
BCR-ABL (quantitative)

4 CURRENT TRENDS FOR DIAGNOSTIC KITS

Today, more and more consumers are taking control of their health and understanding the importance of early detection and treatment. The various types of home diagnostic tests that line the shelves of pharmacies are proof that people are growing health-conscious. Currently, the market for home testing kits stands at about $2.8 billion, compared with only $750 million in 1992. The FDA has approved home testing kits for analysis of more than 26 substances or for detecting conditions such as ovulation, pregnancy, diabetes, drug abuse, high cholesterol, and HIV. At one time, the only home diagnostic tests available were for monitoring blood glucose, pregnancy detection, and ovulation prediction, but now the market is flooded with various types of diagnostic aids that monitor and diagnose illnesses. Many tests that once could be performed only in a doctor’s office but, are now available directly to the consumer. In 2003, various new at-home tests were introduced to the market that included screening for urinary tract infections, digital pregnancy tests, and ovulation tests that use saliva instead of urine[49].

1. Infertility, Ovulation, and Pregnancy Testing: In 2003, ClearBlue Easy (Unipath Diagnostics Inc.) marketed a digital pregnancy test that displays the word “pregnant” or “not pregnant” on the testing device, therefore eliminating error in the interpretation of the results. Also, various manufacturers marketed microscopes that utilize saliva to detect ovulation. These tests appear to be beneficial to females with irregular cycles. Other tests available for couples facing the obstacle of infertility allow males to test sperm concentration.
2. Cholesterol Testing: Cholesterol testing enables individuals to assess their cardiovascular risks and may motivate some people to modify unhealthy lifestyle habits and seek proper medical care from a physician. These tests, however, provide only total cholesterol level and not a complete lipid profile that distinguishes low-density lipoprotein (LDL) from high-density lipoprotein (HDL) rates. Some companies are presently working on a test that will measure HDL, LDL, and triglycerides separately.
3. HIV Testing: In 1996, the FDA approved the first and only in-home HIV testing kit, the Home Access Express HIV-1 test system, manufactured by HomeAccess Health Corp. The blood sample is collected by the consumer and mailed to a laboratory with an identification number. The results are obtained from a trained counselor. Both pre- and post-counseling are available for all consumers.

Point of Care Testing (POCT) is one of the type of at home diagnostic kit. It is a type of diagnosis process where a patient can be diagnosed at a point of care, i.e. can be performed near the patient. At present, POCT ranges from basic blood-glucose measurement to complex viscoelastic coagulation assays. There are analytical devices available that make it possible to process a whole blood sample in a simple manner, allowing untrained staff to carry out laboratory diagnostics. It is clear that the use of POCT shortens the time between sample acquisition and analysis[50]. Recent years have witnessed tremendous advances in point-of-care diagnostics (POCD), which are a result of continuous developments in biosensors, microfluidic, bio-analytical platforms, assay formats, lab-on-a-chip technologies, and complementary technologies[51]. 

Table 6 Synonyms for POCT[52].

POCT	Home testing
Ancillary Testing	Self-management
Satellite Testing	Patient self-management
Bedside Testing	Remote testing
Near Patient Testing	Physician’s office laboratories

Figure 6 Schematic layout for function of POCT diagnostic kits[50]

4.1 Different types of POCT diagnostic kits based on their action of testing

1. Type 1 – Qualitative strip-based POCT methods: These qualitative tests discriminate plus and minus results and are mostly strip-based. The signaling is often performed by simple visualization or by optical detection using a simple readout device.
2. Type 2 – So-called unit-use analyzers: simplest form of quantitative POCT device, with most of the analysis taking place on the respective test strips. The reader is used only to read the result from the strips where the reaction has already taken place. These test strips are one-use articles.
3. Type 3 – So-called bench-top POCT analyzers.
4. Spectrophotometry/reflectrometry: This is usually applied for clinical-chemistry parameters. The analyzers use different test formats [e.g., centrifugal disks for the Piccolo from Abaxis (Union City, CA, USA), test strips for the Triage Meter Pro (Alere Health) or cassette analyzers for the Reflotron (Roche Diagnostics, Mannheim, Germany)].
5. Hematological multichannel analyzers: These use conventional techniques, but are tailored for POCT needs. An example is the PocH-100i from Sysmex (Kobe, Japan).
6. Immunological multi-channel devices: these are tailored for special POCT applications. They use antibody- based immunoassay methodologies.
7. Blood gas analyzers (BGAs): BGAs usepotentiometric/amperometric or optical sensors for pH,pO₂ and pCO₂. Additional ion-sensitive electrodes for themeasurement of electrolytes and other substrates areavailable.
8. Type 4 – Hemostaseological coagulation analyzers: These POCT compatible machines show a high degree of complexity. Although they are valid for use in POCT, only qualified personnel should operate them (e.g., a laboratory physician or a trained technical assistant). The combined analysis of plasma clotting, thrombocyte function and fibrinolysis is termed viscoelastic coagulation testing. These analyzers have to be called pseudo-POCT.
9. Type 5 – Continuous measurement with POCT systems: The most common example here is continuous glucose monitoring. Such analyzing and application systems are already available commercially. They are likely to replace the invasive, intravenous electrode by the minimally invasive location of a micro dialysis catheter in subcutaneous tissue.
10. Type 6 – Molecular biology-based POCT devices to detect infectious agents: At present on the market, there are many qualitative test strips to detect infectious pathogens. The basic principle in most systems is immunochromatography of a specific microbial antigen (or, more rarely, antibody) in the patient sample (urine, swab, or whole blood).

4.2  Certain factors that is increasing current use of point of care testing are as follows[53]

• Healthcare reform and patient-centered care
• Technological advancements (faster, easier-to-use devices)
• Laboratory staff shortages
• Increasing older population and more chronic disease
• Rising incidence of lifestyle diseases (e.g., cardiac, diabetes)
• Increase in home-based POC usage
• Increasing trend toward healthcare decentralization
• Long-term savings
• Rural locations with limited lab services
• Prevalence of diseases in developing countries

4.3 Advantages [54]

• The main aim, and benefit, of POCT is to bring the test conveniently and immediately to the patient. This increases the likelihood that the physician and care team will receive the results quicker, enabling clinicians to support the timely diagnosis, monitoring and treatment of patients.
• Advantage of POCT over Central Laboratory Testing

Figure 7 Advantage of POCT diagnosis[55]

4.4  Disadvantages[54]

• There are many limitations with POCT testing if analysis procedures are not adhered to. It is essential that POCT is undertaken correctly to ensure accurate and reliable results.
• Poor quality of analysis, poor record keeping, a lack of report interpretation, failure to detect abnormal results, unauthorized processing and inappropriate testing are critical areas that directly affect patient results and care.
• POCT devices are unable to detect lipaemic, icteric and haemolysed samples. According to several studies, visual detection is inadequate to determine the presence of lipaemia in whole blood samples. Similarly, haemolysis is impossible to visually detect in whole blood samples and can heavily impair results produced.
• Result quality is often directly related to sample quality; a poor sample or incorrect analytical technique will yield poor results.
• For example, poor blood gas sample preparation handling can often result in incorrect blood gas, pH, hemoglobin and potassium results as a consequence of room air contamination, settling of the cells and haemolysis respectively.
• Put simply, an incorrect test result can result in the wrong treatment and potentially life threatening consequences.

5 FUTURE ASPECTS IN DIAGNOSTIC KITS

A number of novel parameters for POCT applications are under discussion. Potentially interesting, but still clinically unevaluated, new markers for POCT applications are as follows: NGAL, Galectin-3, Copeptin, Preeclampsia[50].

Many of the possibilities of extending the application of POCT depend on the wishes, the needs and the practicalities arising from using POCT, as well as the advantages and the disadvantages for the patient. The future challenges can described as follows[50]:

1. POCT management – Quality assessment: The quality of POCT can be assured only through a POCT-coordination system, Data management of the POCT results is also fundamental to quality. Tight surveillance of POCT data can show error trends before they affect the results. POCT data-management software programs can be categorized into proprietary and non-proprietary.
2. Trends in healthcare: the advantage of outpatient treatment and patient observation in their home environment. The importance of POCT will increase in these areas. In outpatient care, it is clear what advantage immediate diagnostic and therapeutic decisions offers the patient may not need to be further investigated.
3. New areas of use: Though POCT may be used in principle at ‘‘any’’ locale, its use today is mainly centered on various areas of the hospital, general practitioners and patient self-monitoring of glucose and INR. Other emerging field includes mobile emergency paramedical care (blood mobiles, mobiles for public events), transport vehicles (e.g., ambulances and helicopters), sport medicine or competitive sport, outbreaks of disease and catastrophes, remote areas, ‘‘third world’’ countries, military use, at the pharmacy, prisons, alternative-medicine practitioners, corporate healthcare operations, nursing homes, veterinary medicine, fitness studios, & home healthcare.
4. POCT in developing countries: The availability of medical treatment to the populationas a whole is particularly important in developingcountries. The current western systems (e.g., structuredaround a large central hospital) are largely unsuitable;rather a decentralized health system offers the mosteffective means. In this case, a decentralized diagnosticprocess with POCT systems can play a very useful part. The American National Institute of Biomedical Imaging and Bioengineering (NIBIB) has therefore begun co-operation with India, the aim of which is to develop devices, which are suitable for use at the point of need. The International Council for Standardization in Hematology (ICSH) is working on a set of guidelines, which will be applicable worldwide for POCT standardization in hematology and which can also be used in developing countries.

6 CONCLUSION

Significant progress has been made during past years; however, the research on POCT based analytical devices is still in its early stage.Greater & more precise efforts will be needed in this field to develop into widely and precisely used kits to become a morematured platform technology in diagnostic, point-of-care andenvironmental monitoring applications. Despite many potentialfuture directions in this research, here, we hope to convey to thereader just a few of the perspective directions that we think arerelevant and attractive in this field.

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