Diagnostic test: Difference between revisions
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| Simple accuracy|| Easy to understand ||Varies with prevalence of disease | | Simple accuracy|| Easy to understand ||Varies with prevalence of disease | ||
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| Gain in Certainty<ref name="pmid4014166">{{cite journal |author=Connell FA, Koepsell TD |title=Measures of gain in | | Gain in Certainty<ref name="pmid4014166">{{cite journal |author=Connell FA, Koepsell TD |title=Measures of gain in certainty from a diagnostic test |journal=Am. J. Epidemiol. |volume=121 |issue=5 |pages=744–53 |year=1985 |month=May |pmid=4014166 |doi=|url=http://aje.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=4014166 |issn=}}</ref><br/>([[Sensitivity and specificity|Sensitivity]] plus [[Sensitivity and specificity|specificity]]) ||Easy to understand<br/>Stable with prevalence of disease || | ||
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| Youden's ''J'' index<ref name="pmid15405679">{{cite journal |author=Youden WJ |title=Index for rating diagnostic tests |journal=Cancer |volume=3 |issue=1 |pages=32–5 |year=1950 |month=January |pmid=15405679 |doi= |url= |issn=}}</ref><br/>([[Sensitivity and specificity|Sensitivity]] plus[[Sensitivity and specificity|specificity]] minus 1) | | Youden's ''J'' index<ref name="pmid15405679">{{cite journal |author=Youden WJ |title=Index for rating diagnostic tests |journal=Cancer |volume=3 |issue=1 |pages=32–5 |year=1950 |month=January |pmid=15405679 |doi= |url= |issn=}}</ref><br/>([[Sensitivity and specificity|Sensitivity]] plus [[Sensitivity and specificity|specificity]] minus 1) || Easy to understand<br/>Stable with prevalence of disease || | ||
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| Area under the [[receiver operating characteristic curve]] (AROC)<ref name="pmid7063747">{{cite journal| author=Hanley JA, McNeil BJ| title=The meaning and use of the area under a receiver operating characteristic (ROC) curve. | journal=Radiology | year= 1982 | volume= 143 | issue= 1 | pages= 29-36 | pmid=7063747 | | Area under the [[receiver operating characteristic curve]] (AROC)<ref name="pmid7063747">{{cite journal| author=Hanley JA, McNeil BJ| title=The meaning and use of the area under a receiver operating characteristic (ROC) curve. | journal=Radiology | year= 1982 | volume= 143 | issue= 1 | pages= 29-36 | pmid=7063747 | ||
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| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=clinical.uthscsa.edu/cite&retmode=ref&cmd=prlinks&id=17569110 |doi=10.1002/sim.2929 }}</ref><br/>Change in sensitivity plus change in specificity||Stable with prevalence of disease<br/>Can interpret multi-level tests||Hard to understand | | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=clinical.uthscsa.edu/cite&retmode=ref&cmd=prlinks&id=17569110 |doi=10.1002/sim.2929 }}</ref><br/>Change in sensitivity plus change in specificity||Stable with prevalence of disease<br/>Can interpret multi-level tests||Hard to understand | ||
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[[File:Reclassification_table_example.jpg|300px|thumb|right|Net reclassification example]] | |||
== Types of medical tests == | == Types of medical tests == | ||
Revision as of 03:39, 24 April 2023
A diagnostic test is any kind of medical procedure performed to aid in the diagnosis or detection of disease. For example:
- to diagnose diseases
- to measure the progress or recovery from disease
- to confirm that a person is free from disease
A drug test can be a specific medical test to acertain the presence of a certain drug in the body (for example, in drug addicts).
Overview
Some medical tests are parts of a simple physical examination which require only simple tools in the hands of a skilled practitioner, and can be performed in an office environment. Some other tests require elaborate equipment used by medical technologists or the use of a sterile operating theatre environment.
Some tests require samples of tissue or body fluids to be sent off to a pathology lab for further analysis. Some simple chemical tests, such as urine pH, can be measured directly in the doctor's office.
Most medical tests are conducted on the living; however, some of these tests can also be carried out on a dead person as part of an autopsy.
Medical tests can be classified into three categories:
Properties
The result of a test may be positive or negative: this has nothing to do with a bad prognosis, but rather means that the test worked or not, and a certain parameter that was evaluated was present or not. For example, a negative screening test for breast cancer means that no sign of breast cancer could be found (which is in fact very positive for the patient).
Bayesian probability and performance metrics
Other characteristics of tests include:
- sensitivity
- specificity
- positive predictive value
- negative predictive value
- false positive
- false negative
| Method | Advantages | Disadvantages |
|---|---|---|
| Simple accuracy | Easy to understand | Varies with prevalence of disease |
| Gain in Certainty[1] (Sensitivity plus specificity) |
Easy to understand Stable with prevalence of disease |
|
| Youden's J index[2] (Sensitivity plus specificity minus 1) |
Easy to understand Stable with prevalence of disease |
|
| Area under the receiver operating characteristic curve (AROC)[3]and variations[4] | Stable with prevalence of disease Can interpret multi-level and continuous outcome tests |
Hard to understand |
| Diagnostic odds ratio (DOR)[5] | Stable with prevalence of disease Can be included in multivariable analyses |
Hard to understand Underestimates heterogeneity[6] |
| Net reclassification index[7] Change in sensitivity plus change in specificity |
Stable with prevalence of disease Can interpret multi-level tests |
Hard to understand |
Types of medical tests
Consulting room tests
- auscultation, including listening with a stethoscope
- weighing, and measuring height and girth
- measuring blood pressure
- taking the patient's pulse
- breath tests
- reflex tests
- eye examination
- hearing test
- digital rectal examination
- vaginal examination
More invasive examinations requiring sterile procedures
Requiring laboratory analysis
- urine tests
- stool samples
- saliva samples
- hair samples
- blood tests
- ESR
- CBC (complete blood count)
- CMP (comprehensive metabolic panel)
- blood gas monitor
- DNA tests
Requiring microscopy
Requiring elaborate medical equipment
- X-rays
- barium enema
- intravenous pyelogram (IVP test)
- ultrasound scans
- electrocardiogram (EKG)
- electroencephalogram (EEG)
- computer aided tomography scans
- endoscopy
Psychological effects of diagnostic tests
Medical tests can have value when results are abnormal by explaining to a patient the cause of their symptoms[8]. In addition, normal test results can have value by reassuring patients that serious illness is not present and even reduce the rates of subsequent symptoms [9]. Understanding the meaning of a normal test in advance of learning the test results may also reduce the rates of subsequent symptoms [10].
Lack of adequate education about the meaning of test results (especially relevant to tests that may have incidental and unimportant findings) may cause an increase in symptoms [11]. In addition, the possible benefits must be weighed against the costs of unnecessary tests and resulting unnecessary follow-up and possibly even unnecessary treatment of incidental findings [12].
See also
References
- ↑ Connell FA, Koepsell TD (1985). "Measures of gain in certainty from a diagnostic test". Am. J. Epidemiol. 121 (5): 744–53. PMID 4014166. Unknown parameter
|month=ignored (help) - ↑ Youden WJ (1950). "Index for rating diagnostic tests". Cancer. 3 (1): 32–5. PMID 15405679. Unknown parameter
|month=ignored (help) - ↑ Hanley JA, McNeil BJ (1982). "The meaning and use of the area under a receiver operating characteristic (ROC) curve". Radiology. 143 (1): 29–36. PMID 7063747.
- ↑ Leeflang MM, Deeks JJ, Gatsonis C, Bossuyt PM, Cochrane Diagnostic Test Accuracy Working Group (2008). "Systematic reviews of diagnostic test accuracy". Ann Intern Med. 149 (12): 889–97. PMID 19075208.
- ↑ Glas AS, Lijmer JG, Prins MH, Bonsel GJ, Bossuyt PM (2003). "The diagnostic odds ratio: a single indicator of test performance". J Clin Epidemiol. 56 (11): 1129–35. PMID 14615004.
- ↑ Cornell J, Mulrow CD, Localio AR (2008). "Diagnostic test accuracy and clinical decision making". Ann Intern Med. 149 (12): 904–6. PMID 19075211.
- ↑ Pencina MJ, D'Agostino RB, D'Agostino RB, Vasan RS (2008). "Evaluating the added predictive ability of a new marker: from area under the ROC curve to reclassification and beyond". Stat Med. 27 (2): 157–72, discussion 207-12. doi:10.1002/sim.2929. PMID 17569110.
- ↑ Ward B, Wu W, Richter J, Hackshaw B, Castell D (1987). "Long-term follow-up of symptomatic status of patients with noncardiac chest pain: is diagnosis of esophageal etiology helpful?". Am J Gastroenterol. 82 (3): 215–8. PMID 3826028.
- ↑ Sox H, Margulies I, Sox C (1981). "Psychologically mediated effects of diagnostic tests". Ann Intern Med. 95 (6): 680–5. PMID 7305144.
- ↑ Petrie K, Müller J, Schirmbeck F, Donkin L, Broadbent E, Ellis C, Gamble G, Rief W (2007). "Effect of providing information about normal test results on patients' reassurance: randomised controlled trial". BMJ. 334: 352. PMID 17259186.
- ↑ Kendrick D, Fielding K, Bentley E, Kerslake R, Miller P, Pringle M (2001). "Radiography of the lumbar spine in primary care patients with low back pain: randomised controlled trial". BMJ. 322 (7283): 400–5. PMID 11179160.
- ↑ Jarvik J, Hollingworth W, Martin B, Emerson S, Gray D, Overman S, Robinson D, Staiger T, Wessbecher F, Sullivan S, Kreuter W, Deyo R (2003). "Rapid magnetic resonance imaging vs radiographs for patients with low back pain: a randomized controlled trial". JAMA. 289 (21): 2810–8. PMID 12783911.
External links
- Diagnostic medical tests - Informative, educational and user- friendly web site that offers valuable information about laboratory services, diagnostic and medical tests with comprehensive references and information.
- Detecting breast cancer earlier - Breast cancer research foundation web site. Information on breast cancer medical researches that demonstrates the potential for discovering earlier methods of detecting breast cancer.