Carotid IMT and Stiffness in the KiGGS 2 National Survey: Third-Generation Measurement, Quality Algorithms and Determinants of Completeness.

Carotid intima-media thickness (cIMT) and carotid stiffness (CS) are important markers of atherosclerotic risk in the young. We assessed a novel third-generation method for its applicability in large population-based epidemiologic studies to determine strengths, limitations, completeness and predictors of unsuccessful measurement. Four thousand seven hundred ninety-eight 14- to 31-y-old participants of the German KiGGS cohort, which is based on a nationally representative sample with 11-y follow-up, underwent B-mode ultrasound examinations of the left and right common carotid artery with semi-automatic edge detection and automatic electrocardiogram-gated real-time quality control based on a sophisticated snake algorithm and subpixel interpolation. Overall completeness was 98% for far wall cIMT and 89% for CS parameters. Plane-specific completeness varied from 92%-96% for far wall and from 64%-69% for near-wall cIMT. Obesity independently predicted unsuccessful cIMT and CS measurements with odds ratios of 12.67 (95% confidence interval: 5.50-29.19) and 7.30 (4.87-10.94) compared with non-overweight after adjustment for blood pressure, cholesterol, smoking, hazardous drinking, age, sex and sonographer. Inter- and intra-rater reliabilities of cIMT and CS parameters in a sample of 15 young adults were good or excellent. Third-generation cIMT and CS measurements in the young with semi-automatic edge-detection and automatic real-time quality control has been successfully standardized with high reliability and very high completeness in a national survey setting. This provides a strong methodological foundation for further validation of the predictive value of cIMT and CS for atherosclerotic risk in the young.