Footnotes

• Contributors SP drafted the manuscript, acquired the data and performed the analysis. MJ, JP, JL and MA characterised the patients and edited the manuscript. AMS, JT and SS characterised the patients. MS acquired the data. EY and HT acquired the data and edited the manuscript. BU conceived the study, characterised the patients and edited the manuscript.

• Competing interests None declared.

• Ethics approval The local Ethical Committee of the University Hospital of Tampere and the local Ethical Committee of the University Hospital of Helsinki.

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