Footnotes

• Contributors AA, AMV and MD conceived the study. AA performed the data analysis. AA, AMV and MD critically appraised the manuscript and approved the final version.

• Competing interests None declared.

• Patient consent Obtained.

• Ethics approval Nottinghamshire Research Ethics Committee-1.

• Provenance and peer review Not commissioned; externally peer reviewed.

• Data sharing statement Data used in this study are held in Academic Rheumatology, University of Nottingham, UK, under the custody of MD and can be made available on request.