Footnotes

• Contributors DC was involved in the organisation and execution of the research project; design, execution, review and critique of the statistical analysis; writing of the first draft and the review and critique of the manuscript. AM was involved in the execution of the research project; execution, review and critique of the statistical analysis; writing of the first draft and review and critique of the manuscript. AR was involved in the execution of the research project; execution, review and critique of the statistical analysis; review and critique of the manuscript. EP was involved in the execution of the research project; execution of the statistical analysis. AT, AM, LG, MR, RF, MF, GS, ES and EN-O were involved in the execution of the research project; review and critique of the manuscript. LL was guarantor; and involved in the conception and organisation of the research project; critique of the statistical analysis; and review and critique of the manuscript.

• Competing interests DC received honoraria for lecturing from Baxter, CSL Behring, and Kedrion; he received personal compensation for serving on the Advisory Board of CSL Behring, Kedrion and Lilly and travel grants to attend scientific meetings from Baxter, Grifols, Kedrion, and CSL Behring. AT reports travel grants to attend scientific meetings from Kedrion, CSL Behring and Baxter. AM reports travel support for attending scientific meetings from CSL Behring—Italy and Kedrion—Italy. RF received personal compensation for serving on the Advisory Board of CSL Behring and Baxter, and travel grants from Baxter, Grifols, Kedrion and CLS Behring. GS received personal compensation for serving on the Advisory Board from Grunenthal, Baxter and Grifols. EN-O reports personal compensation for serving on the Advisory Board of CSL Behring, Baxter, Kedrion and Novartis; he received honoraria for lecturing, and travel grants to attend scientific meetings from Baxter, CSL Behring, Grifols and Kedrion. EP received travel grant to attend scientific meetings from CSL Behring.

• Patient consent Obtained.

• Ethics approval The authors declare that they acted in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki.

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

• Data sharing statement DC had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.