Received: 27 December 2018
Accepted: 31 May 2019
First Online: 18 June 2019
Change Date: 20 August 2019
Change Type: Correction
Change Details: An error occurred during the publication of a number of articles in <i>BMC Rheumatology</i>. Several articles were published in volume 3 with a duplicate citation number.
Ethics approval and consent to participate
: Ethical approval for the study was received by Ethics Committee in Research Affairs, Tabriz University of Medical Sciences. All respondents were informed about the aim of study and assured on the confidentiality of data and, all signed a consent form.
: Not applicable.
: The authors declare that they have no competing interest.