Eighteen studies (n=44,861, which comprised 2,920 with coronary heart disease and 41,941 without) were included. Six studies used a diagnostic cohort design and 12 were diagnostic case-control studies.
Carotid intima-media thickness (18 studies): The summary intima-media thickness was 0.92mm (95% CI 0.83 to 1.01) in individuals with coronary heart disease and 0.76mm (95% CI 0.68 to 0.84) in individuals without coronary heart disease. There was significant heterogeneity in both measures (p<0.001). Results were similar when stratified according to study design. Intima-media thickness increased with age by 1.4% per year (95% CI 0.7 to 2.1). None of the other variables investigated were associated with intima-media thickness. At a false positive rate of 30% the detection rate was 65%. The summary positive likelihood ratio was 2.2 (95% CI 1.9 to 2.5).
Plaque (eight studies): The summary detection rate was 62% (95% CI 52% to 72%). The summary false positive rate was 30% (95% CI 24% to 37%). There was significant heterogeneity in both measures (p<0.001). Results were similar when stratified according to study design. Presence of plaque increased with age by about 1.5% per year (95% CI 0.3 to 2.8). None of the other variables investigated showed significant associations with the presence of plaque. The summary positive likelihood ratio was 2.1 (95% CI 1.6 to 3.4).