Seventeen studies (22 study arms) were included in the review (2,171 patients, range 17 to 446); it was unclear whether all studies were RCTs. One study scored 2 on the Jadad scale, 10 scored 3, two scored 4 and four scored 5.
Five further studies were published after the final search date but were not included in the meta-analysis. The findings supported those from studies included in the meta-analysis (details reported in the review).
Statin treatment statistically significantly decreased plaque progression (MD -5.33mm³, 95% CI -3.3 to -7.2; 22 study groups) with no statistically heterogeneity (Ι²=0%). Stratified analyses by condition indicated a twofold decrease in plaque volume in patients with acute coronary syndrome compared to patients with stable angina pectoris.
No statistically significant changes were reported by type of plaque composition and there was evidence of significant statistical heterogeneity for fibro-fatty volume (Ι²=91%). Stratified analyses by dose and duration showed a statistically significant reduction in plaque progression only in studies that administered more than 10mg statin with more than six months follow-up (MD -5.2mm³, 95% CI -3.1 to -7.3; nine study groups) with no evidence of statistical heterogeneity.
Plaque volumes were statistically significantly reduced with statin treatment in patients with low-density lipoprotein-cholesterol levels of 70 to 100mg/dL at follow-up (MD -5.7mm³, 95% CI -2.7 to -8.6; 13 study groups) and levels less than 70mg/dL at follow-up (-5.9mm³, 95% CI -2.2 to -9.6; four study groups). There was no significant reduction in plaque volumes in patients with levels more than 100mg/dL. There was evidence of statistical heterogeneity with statin doses of up to 10mg/dL at more than six months follow-up.
Funnel plots indicated low risk of publication bias.