| The evidentiary significance of case reports: eye rubbing and keratoconus. | |
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MedLine Citation:
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PMID: 18382341 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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PURPOSE: Individual case reports (observational or interventional) are thought to have a very low ranking for evidentiary significance. This clinical report examines the relationship between the evidentiary significance of case reports and their presentation. METHODS: An observational report of unilateral keratoconus (KC), that developed in association with a corresponding unilateral chronic habit of abnormal rubbing, is examined to identify features that can raise the level of evidentiary significance. RESULTS: A feature of this type of case is the opportunity to compare the eye with KC to the unaffected eye, for which there was an unremarkable rubbing history. The unaffected eye serves as a retrospective unintentional control for the affected eye. Detailed assessment to establish the normality of the apparently normal eye is crucial to the differential diagnosis between a markedly asymmetric presentation and a true unilateral presentation. Any history of systemic diseases that may be associated with the presenting disease can be important. Longitudinal follow-up, especially if postonset data are supplemented with preonset data, can contribute to the evidentiary base by allowing for comparison with the natural history of the relevant disease. Intervention to remove a suspected causal factor, when combined with appropriate follow-up, can provide additional evidence. CONCLUSIONS: Depending on their presentation, some types of case report can have a significant evidence-based function in assessing causal hypotheses and, accordingly, provide a higher evidentiary ranking than generally assigned to case reports. The potential for a higher evidentiary ranking may be more important when randomized clinical trials are contraindicated for ethical reasons, or there are challenging problems with study design. Wider agreement regarding the quantitative and qualitative criteria for diagnosing the earliest stages of KC would aid the assessment of the evidentiary significance of case reports of this disease. |
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Authors:
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Charles W McMonnies |
Publication Detail:
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Type: Case Reports; Journal Article |
Journal Detail:
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Title: Optometry and vision science : official publication of the American Academy of Optometry Volume: 85 ISSN: 1040-5488 ISO Abbreviation: Optom Vis Sci Publication Date: 2008 Apr |
Date Detail:
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Created Date: 2008-04-02 Completed Date: 2008-08-05 Revised Date: 2009-11-19 |
Medline Journal Info:
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Nlm Unique ID: 8904931 Medline TA: Optom Vis Sci Country: United States |
Other Details:
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Languages: eng Pagination: 262-9 Citation Subset: IM |
Affiliation:
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School of Optometry and Vision Science, University of New South Wales, Kensington, Australia. cmcmonnies@unsw.edu.au |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Follow-Up Studies Genetic Testing Humans Keratoconus / etiology*, genetics Longitudinal Studies Male Medical History Taking Observer Variation Physical Stimulation / adverse effects* |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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