Erratum: Publisher Correction to: BMC Rheumatology, volume 3

[This corrects the article DOI: 10.1186/s41927-019-0072-9.][This corrects the article DOI: 10.1186/s41927-019-0071-x.][This corrects the article DOI: 10.1186/s41927-019-0070-y.][This corrects the article DOI: 10.1186/s41927-019-0069-4.][This corrects the article DOI: 10.1186/s41927-019-0067-6.].