In the TSSMN randomized trial, tweeted articles showed significantly greater increases than non-tweeted controls in: Altmetric score (9.4±5.8 vs. 1.0±1.8, p<0.001), Altmetric score percentile relative to same-journal articles of similar age (76.0±9.1%ile vs. 13.8±22.7%ile, p<0.001), and change in citations at 1 year (+3.1±2.4 vs. +0.7±1.3, p<0.001). Multivariable analysis identified independent predictors of citation growth: randomization to tweeting (OR 9.50, 95% CI 3.30-27.35, p<0.001), Altmetric score (OR 1.32, 95% CI 1.15-1.50, p<0.001), open-access status (OR 1.56, 95% CI 1.21-1.78, p<0.001), and number of Twitter impressions (OR 1.30, 95% CI 1.10-1.49, p<0.001).