Laboratory performance in HTLV-I/II analysis.

BACKGROUND: Since 1989, the CDC's Model Performance Evaluation Program has shipped samples to voluntary participant laboratories that test for HTLV antibodies. Each laboratory tests the well-characterized samples, reports the results, and provides information about its testing practices. The data from 15 performance survey periods are reported here. STUDY DESIGN AND METHODS: Multiple logistic regression was used to analyze all data from 15 survey periods from 1989 through 1996. RESULTS: The mean analytic sensitivity for EIA was 99.2 percent per survey period (range, 96-100%), the mean analytic specificity was 97.8 percent (75.6-100%), and the overall accuracy was 88.8 percent (63.8-100%). The mean analytic sensitivity for Western blot was 88.8 percent (75.6-100%); the mean analytic specificity was 95.7 percent (86.7-100%), and the overall accuracy was 91.1 percent (78.1-100%). CONCLUSIONS: Statistical analyses suggested associations between performance and both the retroviral serologic status of the sample and the analytical testing method. Western blot accuracy was associated with weekly testing volume. In early survey periods, performance problems were noted in the analysis of samples from donors with concomitant HTLV and HIV infections and those from donors who were positive for HTLV-II. Technological developments in test methods, such as the addition of recombinant antigens, appeared to have improved the laboratory performance of specific testing methods.

Is maternal age a risk factor for mental retardation among children?

The purpose of this study was to determine whether older or very young maternal age at delivery is associated with mental retardation in children. Ten-year-old children with mental retardation (an intelligence quotient of 70 or less) were identified in 1985-1987 from multiple sources in the metropolitan Atlanta, Georgia, area. These children were subdivided into two case groups according to whether they had concomitant developmental disabilities or birth defects affecting the central nervous system (codevelopmental retardation) or did not have such disabilities (isolated retardation). Control children were randomly chosen from the regular education files of the public school systems in the study area. Data on sociodemographic variables were gathered from birth certificates. Children of teenaged mothers were not at increased risk for either form of retardation and children of mothers aged > or =30 years were not at increased risk for isolated retardation, in comparison with children of mothers aged 20-29 years. A markedly elevated risk of codevelopmental retardation was seen among black children of mothers aged > or =30 years that was not attributable to Down syndrome. A modest increase in risk for codevelopmental retardation was observed among white children born to older mothers, but it was entirely due to Down syndrome.

Energy cost of walking and of wheelchair propulsion by children with myelodysplasia: comparison with normal children.

The oxygen consumption of 15 myelodysplastic children during walking and propelling a wheelchair was studied. In comparison to normal children, they walked more slower and consumed more oxygen per meter, but had a similar rate of oxygen consumption. A swing-through gait pattern was 33 per cent more energy-efficient than a four-point gait pattern for these children. Wheelchair propulsion produced velocities and energy efficiencies similar to normal children walking. Oxygen consumption and velocity measurements were found to be significantly related to the clinical factors of level of lesion and strength of hip and knee extension. Regression lines and equations are presented to permit prediction of energy cost and efficiency from heart-rate data of myelodysplastic children.