Diagnostic test (medical)
A diagnostic test is, as its name implies, a medical test or series of tests designed to examine a patient's signs or symptoms (what hurts, or what otherwise seems abnormal to the patient) in order to allow a medical practitioner to give a diagnosis (a conclusion) about what is wrong drawn an analysis of the patient's test results. This is the first step in deciding how to treat the ailment or disease.
Some diagnostic tests may be similar to screening tests, however they differ from the latter in that screening tests are designed to discover abnormality before any symptoms are manifested; diagnostic tests take place after the patient has notice symptoms of abnormality, illness or disease.
Interpreting diagnostic tests
Non-specific benefit of tests
Medical tests can have value when results are abnormal by explaining to a patient the cause of their symptoms[1]. 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 [2].
If a normal test result is expected, understanding the meaning of a normal test in advance of learning the test results may reduce the rates of subsequent symptoms.[3][4]
Non-specific harm of tests
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[5] or anxiety[6]. This may be similar to the effects of labeling.[7]
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.[8]
Tests that seem harmless individually, may be harmful when repeated multiple times in a patient. For example in radiology, it is estimated that computed tomography may be contributing to cancer.[9]
References
- ↑ 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.
- ↑ Thomas Mordekhai Laurence (2004). Extreme Clinic -- An Outpatient Doctor's Guide to the Perfect 7 Minute Visit. Philadelphia: Hanley & Belfus. ISBN 1-56053-603-9.
- ↑ 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.
- ↑ Hoefman E, Boer KR, van Weert HC, Reitsma JB, Koster RW, Bindels PJ (2007). "Continuous event recorders did not affect anxiety or quality of life in patients with palpitations". Journal of clinical epidemiology 60 (10): 1060–6. DOI:10.1016/j.jclinepi.2007.01.014. PMID 17884602. Research Blogging.
- ↑ Haynes RB, Sackett DL, Taylor DW, Gibson ES, Johnson AL (1978). "Increased absenteeism from work after detection and labeling of hypertensive patients". N. Engl. J. Med. 299 (14): 741–4. PMID 692548. [e]
- ↑ 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.
- ↑ Brenner DJ, Hall EJ (2007). "Computed tomography--an increasing source of radiation exposure". N. Engl. J. Med. 357 (22): 2277–84. DOI:10.1056/NEJMra072149. PMID 18046031. Research Blogging.