Diagnostic test (medical): Difference between revisions
imported>Robert Badgett No edit summary |
imported>Robert Badgett |
||
| Line 27: | Line 27: | ||
===Delay testing=== | ===Delay testing=== | ||
<!-- under development --> | <!-- under development --> | ||
[[Randomized controlled trial]]s show benefit of immediate versus delayed testing in patients without possible emergent conditions.<ref name="pmid11179160">{{cite journal |author=Kendrick D, Fielding K, Bentley E, Kerslake R, Miller P, Pringle M |title=Radiography of the lumbar spine in primary care patients with low back pain: randomised controlled trial |journal=BMJ |volume=322 |issue=7283 |pages=400-5 |year=2001 |pmid=11179160}}</ref><ref name="pmid12783911">{{cite journal |author=Jarvik J, Hollingworth W, Martin B, Emerson S, Gray D, Overman S, Robinson D, Staiger T, Wessbecher F, Sullivan S, Kreuter W, Deyo R |title=Rapid magnetic resonance imaging vs radiographs for patients with low back pain: a randomized controlled trial |journal=JAMA |volume=289 |issue=21 |pages=2810-8 |year=2003 |pmid=12783911}}</ref> | [[Randomized controlled trial]]s show benefit of immediate versus delayed testing in patients without possible emergent conditions.<ref name="pmid11179160">{{cite journal |author=Kendrick D, Fielding K, Bentley E, Kerslake R, Miller P, Pringle M |title=Radiography of the lumbar spine in primary care patients with low back pain: randomised controlled trial |journal=BMJ |volume=322 |issue=7283 |pages=400-5 |year=2001 |pmid=11179160}}</ref><ref name="pmid12783911">{{cite journal |author=Jarvik J, Hollingworth W, Martin B, Emerson S, Gray D, Overman S, Robinson D, Staiger T, Wessbecher F, Sullivan S, Kreuter W, Deyo R |title=Rapid magnetic resonance imaging vs radiographs for patients with low back pain: a randomized controlled trial |journal=JAMA |volume=289 |issue=21 |pages=2810-8 |year=2003 |pmid=12783911}}</ref> The benefit may be in part due to successful empirical treatment. | ||
===Establish an alternative diagnoses=== | ===Establish an alternative diagnoses=== | ||
Revision as of 14:35, 9 December 2007
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]
Strategies to reduce unnecessary diagnostic testing
Improve availability of prior results
Sometimes testing is redundant.[10] Having the results of prior tests available may reduce the need for repeating tests.[11] A randomized controlled trial has shown reduction i ordering of redundant tests.[12]
Delay testing
Randomized controlled trials show benefit of immediate versus delayed testing in patients without possible emergent conditions.[5][8] The benefit may be in part due to successful empirical treatment.
Establish an alternative diagnoses
Studies show that the chance of thromboembolism is less in patients who have have alternative explanations for their symptoms.
Patients with chronic abdominal symptoms are less likely to have underlying organic disease if they meet criteria for irritable bowel.
Among patients referred for endoscopy, psychiatric diagnoses are associated with normal endoscopies.[13]
Recognize futility of testing when disease prevalence is extremely low
Examples where thresholds are established to justify testing include:
- HIV screening - the threshold is very low
- New seizure - the threshold is very low
- Pharyngitis
- Influenza
A randomized controlled trial showed a small reduction in test ordering when a computer displayed very low probabilities that a test would be abnormal.[14]
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.
- ↑ 5.0 5.1 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]
- ↑ 8.0 8.1 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.
- ↑ Bates DW, Boyle DL, Rittenberg E, et al (1998). "What proportion of common diagnostic tests appear redundant?". Am. J. Med. 104 (4): 361–8. PMID 9576410. [e]
- ↑ Tierney WM, McDonald CJ, Martin DK, Rogers MP (1987). "Computerized display of past test results. Effect on outpatient testing". Ann. Intern. Med. 107 (4): 569–74. PMID 3631792. [e]
- ↑ Bates DW, Kuperman GJ, Rittenberg E, et al (1999). "A randomized trial of a computer-based intervention to reduce utilization of redundant laboratory tests". Am. J. Med. 106 (2): 144–50. PMID 10230742. [e]
- ↑ O'Malley PG, Wong PW, Kroenke K, Roy MJ, Wong RK (1998). "The value of screening for psychiatric disorders prior to upper endoscopy". Journal of psychosomatic research 44 (2): 279–87. PMID 9532557. [e]
- ↑ Tierney WM, McDonald CJ, Hui SL, Martin DK (1988). "Computer predictions of abnormal test results. Effects on outpatient testing". JAMA 259 (8): 1194–8. PMID 3339821. [e]