Footnotes

• Contributors Study concept and design: ELK, CP, CLMK, DP-S, DvdK, MTN, MTL-C, RW, TR, GW. Acquisition of data: ELK, CP, DP-S. Analysis and interpretation of the data: ELK, CP, GW. Clinical revision and drafting of the manuscript for important intellectual content: ELK, CP, CLMK, DP-S, Dv dK, MTN, MTL-C, RW, TR, GW. Obtained funding: none. Study supervision: MTN, GW. Final approval: ELK, CP, CLMK, DP-S, DvdK, MTN, MTL-C, RW, TR, GW.

• Competing interests MTN reports having received consultancy fees from Abbott, Roche, Pfizer, MSD, UCB, SOBI and BMS, payment for lectures from Abbott, Roche and Pfizer. GW reports having received a research grant from Pfizer (Wyeth) (paid to the institution) and payments for lectures from Pfizer, UCB, Abbvie and Amgen. CLMK reports having received payment for lectures from AbbVie and Pfizer. TR reports having received payment for lectures from AbbVie and Pfizer. CP reports having received a research grant from Pfizer. DP-S reports having received payments for lectures from Pfizer and a research grant from Pfizer. ELK reports having received payments for lectures from Pfizer. DvdK, MTL-C and RW have no disclosures

• Patient consent Obtained.

• Ethics approval The study was approved by the Medical Ethics Committee of the Slotervaart Hospital and Jan van Breemen Research Institute | Reade, Amsterdam (The Netherlands) and La Paz Hospital, Madrid (Spain).

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