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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/11451

Title: Reproducibility of color Doppler imaging
Authors: Stalmans, Ingeborg
Siesky, Brent
Zeyen, Thierry
FIEUWS, Steffen
Harris, Alon
Issue Date: 2009
Publisher: SPRINGER
Abstract: The aims of this study were: (1) to determine the intra-subject and inter-observer variability of color Doppler imaging (CDI) measurements and readings of the retrobulbar blood vessels, (2) to compare the difference in variability of CDI parameters in non-glaucomatous controls versus glaucoma patients, and (3) to provide calculations of minimum sample sizes for future CDI studies. Patients with normal tension glaucoma (n = 28), primary open-angle glaucoma (n = 19) and non-glaucomatous controls of comparable age (n = 22) underwent CDI on two occasions 1 month apart. Variability in CDI parameters was quantified using (within-subject) coefficients of variation. Based on this variability, minimum sample sizes were calculated to guide the design of future studies comparing CDI between and within groups. In general, within-subject coefficients of variation for measurements 1 month apart were comparable to previously reported short-term variations. Variability was higher in glaucoma patients than in non-glaucomatous controls. The minimum sample size required for glaucomatous study populations is larger than for non-glaucomatous controls. Smaller patient groups are required to detect change using the peak systolic blood flow velocities than using end diastolic velocities. Studies using a cross-over design require smaller sample sizes than studies with a pre-post or particularly parallel design. This study provides extensive information on long-term intra-subject variability of CDI measurements in non-glaucomatous controls as well as glaucoma patients. Moreover, sample size calculations are provided for studies involving glaucoma patients as well as non-glaucomatous individuals, using three different commonly used study designs.
Notes: [Stalmans, Ingeborg; Zeyen, Thierry] Univ Hosp Leuven, Dept Ophthalmol, B-3000 Louvain, Belgium. [Siesky, Brent; Harris, Alon] Indiana Univ, Sch Med, Dept Ophthalmol, Indianapolis, IN 46202 USA. [Fieuws, Steffen] Catholic Univ Louvain, B-3000 Louvain, Belgium. [Fieuws, Steffen] Univ Hasselt, B-3000 Louvain, Belgium. ingeborg.stalmans@uzleuven.be; steffen.fieuws@med.kuleuven.be; alharris@indiana.edu
URI: http://hdl.handle.net/1942/11451
DOI: 10.1007/s00417-009-1178-3
ISI #: 000270541500010
ISSN: 0721-832X
Category: A1
Type: Journal Contribution
Validation: ecoom, 2010
Appears in Collections: Research publications

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