Data synthesis and statistical analysis
Meta-analysis was carried out comparing the effect of all QI interventions on the performance of rarely appropriate echocardiography testing and also analyzed based on short-term (< 3 months) and long-term (>3 months) effects. Subgroup analysis was performed for specific QI interventions, including Feedback Tool, Education Tool, or Decision Support Tool. Statistical analysis was performed using comprehensive meta-analysis software.9The extent of heterogeneity was determined by I2 (ranging from 0% to 100%). Due to high heterogeneity, we used a random-effects model to examine the effect and outcomes, which were presented as odds ratio (OR) with Z-value. Statistical significance was considered with a P-value < 0.05 and all tests were 2-sided. Funnel plot of standard error by log HR was created to qualitatively assess publication bias.