Assessing the impact of retraction on the citation of randomized controlled trial reports: an interrupted time-series analysis

Objectives To assess the impact of retraction on the citation of randomized controlled trials. Methods We used an interrupted time-series with matched controls. PubMed, CINHAL, Google and the Retraction Watch Database were searched. We identified retracted publications reporting the results of randomized controlled trials involving human participants with two years of available data before and after retraction. We obtained monthly citation counts across all articles for the 24 months before and after retraction, from Web of Science. We used a Poisson segmented regression to detect changes in the level and trend of citation following retraction. We also undertook a matched control analysis of unretracted randomized controlled trials and a sensitivity analysis to account for cases of large-scale, well-advertised fraud. Results We identified 387 retracted randomized controlled trial reports, of which 218 (56.3%) were included in the interrupted time-series analysis. A reduction of 22.9% (95% CI 4.0% to 38.2%, p = 0.02) was observed in the number of citations in the month after retraction, and a further reduction of 1.9% (95% CI 0.4% to 3.5%, p = 0.02) per month in the following 24 months, relative to the expected trend. There was no evidence of a statistically significant reduction among the matched controls. Authors with a large number of retractions saw a 48.2% reduction at the time of retraction (95% CI 17.7% to 67.3%, p = 0.01). Other cases had a more gradual reduction with no change at the time of retraction and a 1.8% reduction per month in the following 24 months (95% CI 0.2% to 3.4%, p = 0.03). Conclusions Retractions of randomized controlled trial reports can be effective in reducing citations. Other factors, such as the scale of the retractions and media attention, may play a role in the effectiveness of the reduction.