Factors associated with citation rate of randomised controlled trials in physiotherapy

BACKGROUND: Despite the use of citation rate as a measure of quality of research is strongly criticized and debated, it remain a widely used method to evaluate performances of researchers, articles and journals. The aim of this study was to test which factors are associated with citation rate of Randomised Controlled Trials (RCTs) published on the physiotherapy field. METHODS: All RCTs abstracted in the Physiotherapy Evidence Database (PEDro), indexed in Scopus database and published in 2008 were included. PEDro score, language of publication, indexing in PubMed database, type of access to articles, subdiscipline, the number of authors, the country where the study was performed, the type of institution where the study was conducted and the number of centres involved in the study (multicentric vs single-centre). and the 2013 5-year impact factor of the publishing journals were considered as independent variables. Citation rate until December 2013 was extracted from Scopus database and used as dependent variable. RESULTS: Six hundred and nineteen RCTs, published in 283 journals, were included and analysed. The 5-year impact factor was the strongest variable associated with the citation rate and explained approximately 50 % of the variance, and the number of authors explained an additional small part (about 1 %) of variability. The other variables were excluded from the model. CONCLUSIONS: The study highlights that 5-year Impact Factor, not accessibility (language of publication, indexing in PubMed database or the type of access to articles) or reported quality (PEDro score), is a strong predictor of the number of citations for RCTs in the physiotherapy field. Our findings support the increasingly widespread idea that citation analysis does not reflect the scientific merit of the cited work, at least in terms of reported quality. The results of this study need to be confirmed with a publication window larger than one year.