| Repeatability of measurements of effectiveness of glaucoma medication. | |
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MedLine Citation:
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PMID: 22989663 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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AIMS: To determine short-term repeatability of the effect of intraocular pressure (IOP) reducing medication and the number of repeated measurements necessary to estimate therapeutic effect with a given degree of precision. METHODS: IOP was measured at 8:00, 11:00 and 16:00 h at each of three weekly visits in untreated patients with primary open-angle glaucoma or ocular hypertension. After starting travaprost (0.004%) to both eyes, the measurements were repeated for a further three weekly visits. Repeatability of the change in IOP 1, 2 and 3 weeks after starting treatment was reported as the coefficient of repeatability (CR) and coefficient of variability (CV). RESULTS: Mean reduction in IOP was 7.5 mm Hg (29.9%). CR and CV between visits were 7.8 mm Hg and 37.2%, respectively. Repeated estimates of the effectiveness of treatment in the same subject at the same time of day would, therefore, be expected to lie within a range of 7.8 mm Hg and within ±73.2% of the mean effect with 95% confidence. A reduction in IOP less than 7.8 mm Hg over a single pair of measurements would be indistinguishable from measurement error. Precision improves from ±73.2% for a single pair of readings to ±25.9% for eight pairs. CONCLUSIONS: Day-to-day repeatability in the estimation of medication effectiveness is poor even for time-of-day standardised measurements and the number of IOP measurements required to achieve precision adequate for use in clinical practice is large. |
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Authors:
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Alan P Rotchford; Anthony J King |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2012-9-18 |
Journal Detail:
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Title: The British journal of ophthalmology Volume: - ISSN: 1468-2079 ISO Abbreviation: Br J Ophthalmol Publication Date: 2012 Sep |
Date Detail:
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Created Date: 2012-9-19 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0421041 Medline TA: Br J Ophthalmol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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Tennent Institute of Ophthalmology, Gartnavel Hospital, Glasgow, UK. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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