title: Need for precision studies at individual institutions and assessment of size of regions of interest on serial DXA scans.
abstract: Precision error is an important quality-control issue in bone densitometry. A prospective trial was completed to evaluate whether significance of change on serial scans, calculated using least significant change data and 95% confidence intervals, from a short-time precision error study, agreed with significance of change data determined by internal Hologic scanner software. In addition, the constancy of specific bone areas scanned of regions of interest on serial scans was evaluated. There was perfect agreement regarding significance of change on serial scans in the femoral neck between the Hologic software and internal precision data. There was not perfect agreement in the total spine; however, the difference was not statistically significant. There was a significant disagreement in the total hip and trochanter between the manufacturer's software and the precision study. The mean change in the area of the region of interest on serial scans was < or =5% in the total spine, total hip, and femoral neck. The mean difference in the trochanter was 7.4+/-6.3%. The importance of doing an internal precision error study is underscored because significance of change from an internal precision study may not agree with manufacturer software. The trochanter may be less useful in monitoring serial changes if area of the region of interest varies widely.
authors.affiliation: University of Alabama at Birmingham Osteoporosis Prevention and Treatment Clinic, Birmingham, AL 35294-1270, USA. slmorgan@uab.edu
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Morgan
authors.forename: William
authors.initials: W
authors.lastname: Abercrombie
authors.forename: Jeannette Y
authors.initials: JY
authors.lastname: Lee
mesh_terms: D015502:Absorptiometry, Photon / Q000592:standards*; D000328:Adult; D001823:Body Composition; D005260:Female; D005269:Femur / Q000502:physiology; D005272:Femur Neck / Q000502:physiology; D006615:Hip / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011786:Quality Control; D012984:Software; D013131:Spine / Q000502:physiology